Flow Master User's Guide

®

FLOWMASTER USER ’S GUIDE

DAA038680-1/0001

Copyright © 1986-2009 Haestad Methods, Inc. All rights reserved. FlowMaster User’s Guide. This documentation is published by Haestad Methods, Inc. (“Haestad”), and is intended solely for use in conjunction with Haestad’s software. This documentation is available to all current Licensees in print and electronic format. No one may copy, photocopy, reproduce, translate, or convert to any electronic or machine-readable form, in whole or in part, the printed documentation without the prior written approval of Haestad. Licensee may download the electronic documentation from Haestad’s web site and make that documentation available solely on licensee’s intranet. Licensee may print the electronic documentation, in part or in whole, for personal use. No one may translate, alter, sell, or make available the electronic documentation on the Internet, transfer the documentation by FTP, or display any of the documentation on any web site without the prior written approval of Haestad. Trademarks The following are registered trademarks of Haestad Methods, Inc.: ClientCare, CulvertMaster, Cybernet, FlowMaster, PondPack, SewerCAD, StormCAD, and WaterCAD. The following are trademarks of Haestad Methods, Inc.: Darwin, DrainageMaster, FlowMaster, HECPack, POND-2, Graphical HEC-1, Graphical HEC-Pack, PondGEMS, and WaterGEMS. Haestad Methods is a registered tradename of Haestad Methods, Inc. AutoCAD is a registered trademark of Autodesk, Inc. ESRI is a registered trademark of Environmental Systems Research Institute, Inc. Microsoft, Windows, Windows NT, Visual Studio, Word, and Excel, are registered trademarks of Microsoft Corporation. SentinelLM is a trademark of Rainbow Technologies, Inc. All other brands, company or product names, or trademarks belong to their respective holders. Portions of this document include intellectual property of ESRI and its licensor(s) and are used herein under license. Copyright © 1999-2002 ESRI and its licensor(s). All rights reserved.

37 Brookside Road Waterbury, CT 06708-1499 USA Phone: +1-203-755-1666 Fax: +1-203-597-1488 E-mail: [email protected] Internet: http://www.haestad.com

Contents Chapter 1: Orientation

1

What’s New in FlowMaster? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1 Using the FlowMaster Documentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 Minimum System Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2 Installing FlowMaster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3 Installing FlowMaster on a Single Computer. . . . . . . . . . . . . . . . . . . . . . . . . . 1-4 Installing FlowMaster for Deployment Across a Network . . . . . . . . . . . . . . . . 1-5 Installing SentinelLM™ License Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6 Using SentinelLM License Manager . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7 Uninstalling FlowMaster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8 How Do I?—Frequently Asked Questions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9 Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9 Contacting Haestad Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9 Sales . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9 Technical Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10 SUPPORT HOURS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-10 Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-11 Haestad Methods’ Workshops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-11 Your Suggestions Count . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-11

Chapter 2: Tutorials

13

Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-13 Tutorial 1—Creating a New Project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-13 Tutorial 2—Gradually Varied Flow Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . 2-18 Tutorial 3—Results Reporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-21

Chapter 3: FlowMaster Environment

27

Welcome Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-28 Main Window. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-28 Project Explorer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-28 Project Files. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-29

FlowMaster User’s Guide

Contents-i

Engineering Library Explorer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-30 Menus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-31 Toolbars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-35 Create New Worksheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-37 Channel Worksheet Dialog Boxes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-38 Rectangular Channel Dialog Boxes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-39 UNIFORM FLOW TAB—RECTANGULAR CHANNEL . . . . . . . . . . . . . . . . . . . . . 3-39 GRADUALLY VARIED FLOW TAB—RECTANGULAR CHANNEL . . . . . . . . . . . . . 3-40 Triangular Channel Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-42 UNIFORM FLOW TAB—TRIANGULAR CHANNEL . . . . . . . . . . . . . . . . . . . . . . . 3-42 GRADUALLY VARIED FLOW TAB—TRIANGULAR CHANNEL . . . . . . . . . . . . . . . 3-43 Trapezoidal Channel Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-44 UNIFORM FLOW TAB—TRAPEZOIDAL CHANNEL . . . . . . . . . . . . . . . . . . . . . . 3-45 GRADUALLY VARIED FLOW TAB—TRAPEZOIDAL CHANNEL . . . . . . . . . . . . . . 3-46 Gutter Section Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-47 Irregular Section Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-48 UNIFORM FLOW TAB—IRREGULAR SECTION . . . . . . . . . . . . . . . . . . . . . . . . 3-49 GRADUALLY VARIED FLOW TAB—IRREGULAR SECTION . . . . . . . . . . . . . . . . 3-50 Parabolic Channel Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-51 UNIFORM FLOW TAB—PARABOLIC CHANNEL . . . . . . . . . . . . . . . . . . . . . . . . 3-52 GRADUALLY VARIED FLOW TAB—PARABOLIC CHANNEL . . . . . . . . . . . . . . . . 3-53 Pipe Worksheet Dialog Boxes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-54 Pressure Pipe Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-55 Circular Pipe Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-56 UNIFORM FLOW TAB—CIRCULAR PIPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-57 GRADUALLY VARIED FLOW TAB—CIRCULAR PIPE . . . . . . . . . . . . . . . . . . . . 3-58 Box Pipe Worksheet Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-59 UNIFORM FLOW TAB—BOX PIPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-60 GRADUALLY VARIED FLOW TAB—BOX PIPE . . . . . . . . . . . . . . . . . . . . . . . . 3-61 Elliptical Pipe Section Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-62 UNIFORM FLOW TAB—ELLIPTICAL PIPE . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-62 GRADUALLY VARIED FLOW TAB—ELLIPTICAL PIPE. . . . . . . . . . . . . . . . . . . . 3-64 Weir Worksheet Dialog Boxes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-65 Rectangular Weir Dialog Box. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-65 V-Notch Weir Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-66 Cipoletti Weir Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-67 Broad Crested Weir Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-68 Generic Weir Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-69 Orifice Worksheet Dialog Boxes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-70 Rectangular Orifice Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-70 Circular Orifice Dialog Box. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-71 Generic Orifice Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-72 Inlet Worksheet Dialog Boxes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-72 Grate Inlet in Sag Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-73

Contents-ii


GUTTER TAB—GRATE INLET IN SAG. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GRATE TAB—GRATE INLET IN SAG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OUTPUT—GRATE INLET IN SAG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Grate Inlet on Grade Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GUTTER TAB—GRATE INLET ON GRADE . . . . . . . . . . . . . . . . . . . . . . . . . . . GRATE TAB—GRATE INLET ON GRADE . . . . . . . . . . . . . . . . . . . . . . . . . . . . OUTPUT—GRATE INLET ON GRADE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Curb Inlet in Sag Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GUTTER TAB—CURB INLET IN SAG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CURB TAB—CURB INLET IN SAG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OUTPUT—CURB INLET IN SAG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Curb Inlet on Grade Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GUTTER TAB—CURB INLET ON GRADE . . . . . . . . . . . . . . . . . . . . . . . . . . . . CURB TAB—CURB INLET ON GRADE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OUTPUT—CURB INLET ON GRADE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ditch Inlet in Sag Dialog Box. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DITCH TAB—DITCH INLET IN SAG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GRATE TAB—DITCH INLET IN SAG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . OUTPUT—DITCH INLET IN SAG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ditch Inlet on Grade Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . DITCH TAB—DITCH INLET ON GRADE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GRATE TAB—DITCH INLET ON GRADE . . . . . . . . . . . . . . . . . . . . . . . . . . . . OUTPUT—DITCH INLET ON GRADE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Slotted Drain Inlet in Sag Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GUTTER TAB—SLOTTED DRAIN INLET IN SAG . . . . . . . . . . . . . . . . . . . . . . . SLOT TAB—SLOTTED DRAIN INLET IN SAG . . . . . . . . . . . . . . . . . . . . . . . . . OUTPUT—SLOTTED DRAIN INLET IN SAG . . . . . . . . . . . . . . . . . . . . . . . . . . Slotted Drain Inlet on Grade Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . GUTTER TAB—SLOTTED DRAIN INLET ON GRADE . . . . . . . . . . . . . . . . . . . . SLOT TAB—SLOTTED DRAIN INLET ON GRADE . . . . . . . . . . . . . . . . . . . . . . OUTPUT—SLOTTED DRAIN INLET ON GRADE . . . . . . . . . . . . . . . . . . . . . . . Combination Inlet in Sag Dialog Box. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GUTTER TAB—COMBINATION INLET IN SAG . . . . . . . . . . . . . . . . . . . . . . . . INLET TAB—COMBINATION INLET IN SAG . . . . . . . . . . . . . . . . . . . . . . . . . . GRATE TAB—COMBINATION INLET IN SAG . . . . . . . . . . . . . . . . . . . . . . . . . CURB TAB—COMBINATION INLET IN SAG . . . . . . . . . . . . . . . . . . . . . . . . . . OUTPUT—COMBINATION INLET IN SAG . . . . . . . . . . . . . . . . . . . . . . . . . . . . Combination Inlet on Grade Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . GUTTER TAB—COMBINATION INLET ON GRADE . . . . . . . . . . . . . . . . . . . . . INLET TAB—COMBINATION INLET ON GRADE. . . . . . . . . . . . . . . . . . . . . . . . GRATE TAB—COMBINATION INLET ON GRADE . . . . . . . . . . . . . . . . . . . . . . CURB TAB—COMBINATION INLET ON GRADE . . . . . . . . . . . . . . . . . . . . . . . OUTPUT—COMBINATION INLET ON GRADE . . . . . . . . . . . . . . . . . . . . . . . . .

3-73 3-74 3-74 3-75 3-76 3-76 3-77 3-78 3-78 3-79 3-79 3-80 3-80 3-80 3-81 3-81 3-82 3-82 3-83 3-84 3-84 3-84 3-85 3-86 3-87 3-87 3-87 3-88 3-88 3-89 3-89 3-90 3-90 3-91 3-91 3-92 3-92 3-93 3-93 3-94 3-94 3-95 3-95

Combination Inlet Options Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-96 Rating Table Setup Dialog Box. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-97 Rating Table Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-97


Contents-iii

Rating Curve Setup Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-98 Rating Curve Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-98 Cross Section Report Setup Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-99 Cross Section Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-99 Irregular Section Editor Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-99 Weighted Roughness Method Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . .3-100 Open and Closed Channel Weighting Methods. . . . . . . . . . . . . . . . . . . . . . 3-100 Note to HEC-2, WSP-2, and WSPRO Users . . . . . . . . . . . . . . . . . . . . . . . . 3-103 FlexUnits Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-103 Project Properties Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-104 GVF Profile Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-105 GVF Profile Table Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-105 Tabular Reports Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-106 Print Preview Dialog Box. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-106 Set Field Options Dialog Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3-107

Chapter 4: How Do I…

109

Create A New Project. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-110 Creating a New Project From the Welcome Dialog Box . . . . . . . . . . . . . . . 4-110 Creating a New Project from the Main Window . . . . . . . . . . . . . . . . . . . . . . 4-110 Open an Existing Project. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-111 Create a New Worksheet? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-111 Name a Worksheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-112 Edit a Worksheet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-112 Create a Rating Table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-113 Plot Rating Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-114 Plot a Cross Section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-115 Print a Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-115 Set Field Options (Unit, Precision, Format) . . . . . . . . . . . . . . . . . . . . . . . . . . 4-116 Save a Project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-116 Exit FlowMaster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-116

Chapter 5: FlowMaster Theory

117

Uniform Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-117 Manning’s Formula . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-119 Kutter’s Formula . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-119

Contents-iv


Hazen-Williams Formula . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-120 Darcy-Weisbach Formula . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-121 Critical Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-122 Basic Concepts of Critical Flow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-124 Hydraulic and Energy Grades . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-124 THE ENERGY PRINCIPLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-124 THE ENERGY EQUATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-125 HYDRAULIC GRADE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-126 ENERGY GRADE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-126 HGL CONVERGENCE TEST. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-126 Friction Loss Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-127 CHÉZY’S EQUATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-127 KUTTER ’S EQUATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-128 MANNING’S EQUATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-128 DARCY-WEISBACH EQUATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-129 SWAMEE AND JAIN EQUATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-131 COLEBROOK-WHITE EQUATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-131 HAZEN-WILLIAMS EQUATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-132 Flow Regime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-132 PRESSURE FLOW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-133 UNIFORM FLOW AND NORMAL DEPTH. . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-133 CRITICAL FLOW, CRITICAL DEPTH, AND CRITICAL SLOPE. . . . . . . . . . . . . . 5-133 Subcritical Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-134 Supercritical Flow. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-134

Gradually Varied Flow Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-134 Slope Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-134 Hydraulically Steep Slope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-135 Critical Slope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-135 Hydraulically Mild Slope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-135 Zone Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-135 Profile Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-135 Energy Balance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-138 STANDARD STEP METHOD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-139 DIRECT STEP METHOD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-139 Mixed Flow Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-139 SEALING (SURCHARGING) CONDITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . 5-139 RAPIDLY VARIED FLOW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-139 Backwater Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-140 Frontwater Analysis. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-141 Weir Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-141 Sharp-Crested Weirs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-141 RECTANGULAR SHARP-CRESTED WEIR . . . . . . . . . . . . . . . . . . . . . . . . . . 5-142 V-NOTCH SHARP-CRESTED WEIR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-143 CIPOLLETTI SHARP-CRESTED WEIR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-144 SUBMERGED SHARP-CRESTED WEIR . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-145 Non-Sharp-Crested Weirs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-146


Contents-v

BROAD-CRESTED WEIR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-146 TRIANGULAR AND TRAPEZOIDAL WEIR. . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-148 Orifice Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-149 Orifice Coefficients. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-149 SLUICE GATE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-149 Pressure Pipe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-150 Hydraulic Grade and Energy Grade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-151 Inlet Hydraulics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-151 HEC-22 Inlet Comparison . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-152 Flows in Gutters on Grade. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-152 UNIFORM GUTTER CROSS SLOPE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-152 COMPOSITE GUTTER SECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-154 Flow in Ditch or Median Section on Grade . . . . . . . . . . . . . . . . . . . . . . . . . 5-156 Inlet Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-157 INLETS ON GRADE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-158 Grate Inlet on Grade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-159 Curb Inlet on Grade . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-161 Slot Inlet on Grade. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-163 Combination Inlet on Grade. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-163 INLETS IN SAG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-164 Grate Inlet in Sag. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-164 Curb Inlet in Sag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-165 WEIR FLOW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-166 ORIFICE FLOW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-167 TRANSITION FLOW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-168 Slot Inlet in Sag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-168 WEIR FLOW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-168 ORIFICE FLOW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-169 TRANSITIONAL FLOW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-169 Combination Inlet in Sag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-169 EQUAL LENGTH INLETS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-169 SWEEPER INLET . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-170

Chapter 6: Pavement Drainage

171

Design Frequency and Spread . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-172 Selection of Design Frequency and Design Spread . . . . . . . . . . . . . . . . . . 6-172 Selection of Check Storm and Spread . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-174 Surface Drainage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-175 Hydroplaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-175 Longitudinal Slope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-176 Cross (Transverse) Slope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-177 Curb and Gutter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-178 Roadside and Median Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-179 Bridge Decks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-180

Contents-vi


Median Barriers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-180 Impact Attenuators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-181 Flow in Gutters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-181 Capacity Relationship . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-181 Conventional Curb and Gutter Sections . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-183 CONVENTIONAL GUTTERS OF UNIFORM CROSS SLOPE . . . . . . . . . . . . . . . 6-183 COMPOSITE GUTTER SECTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-184 CONVENTIONAL GUTTERS WITH CURVED SECTIONS . . . . . . . . . . . . . . . . . 6-189 Shallow Swale Sections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-189 V-SECTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-189 CIRCULAR SECTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-192 Flow in Sag Vertical Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-194 Relative Flow Capacities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-195 Gutter Flow Time. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-197 Drainage Inlet Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-198 Inlet Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-199 Characteristics and Uses of Inlets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-199 Inlet Capacity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-200 FACTORS AFFECTING INTERCEPTION CAPACITY AND EFFICIENCY ON CONTINUOUS GRADES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-207 FACTORS AFFECTING INLET INTERCEPTION CAPACITY IN SAG LOCATIONS . 6-209 COMPARISON OF INTERCEPTION CAPACITY OF INLETS ON GRADE . . . . . . . 6-209 Interception Capacity of Inlets on Grade . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-213 GRATE INLETS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-213 CURB-OPENING INLETS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-219 SLOTTED INLETS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-224 Combination Inlets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-225

Interception Capacity of Inlets in Sag Locations . . . . . . . . . . . . . . . . . . . . . GRATE INLETS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CURB-OPENING INLETS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . COMBINATION INLETS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Inlet Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GEOMETRIC CONTROLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . INLET SPACING ON CONTINUOUS GRADES . . . . . . . . . . . . . . . . . . . . . . . . FLANKING INLETS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Median, Embankment, and Bridge Inlets . . . . . . . . . . . . . . . . . . . . . . . . . . MEDIAN AND ROADSIDE DITCH INLETS . . . . . . . . . . . . . . . . . . . . . . . . . . . EMBANKMENT INLETS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6-229 6-230 6-232 6-239 6-241 6-242 6-242 6-252 6-255 6-255 6-261

Grate Type Selection Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-262


Contents-vii

Chapter 7: HEC 22 Charts

265

Chapter 8: Engineer’s Reference

295

Energy Equation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-295 Roughness Values—Manning’s Equation . . . . . . . . . . . . . . . . . . . . . . . . . . .8-296 Roughness Values—Kutter’s Equation . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8-298 Roughness Values—Darcy-Weisbach (Colebrook-White) Equation . . . . . .8-300 Roughness Values—Hazen-Williams Formula . . . . . . . . . . . . . . . . . . . . . . .8-301

Index

Contents-viii

303


Chapter

1

Orientation

Thank you for purchasing Bentley FlowMaster. At Bentley Systems, we pride ourselves in providing the very best engineering software available. Our goal is to make software that is easy to install and use, yet so powerful and intuitive that it anticipates your needs without getting in your way. Bentley FlowMaster is a feature-rich program with extensive online documentation, which provides a level of instruction appropriate to your needs. When you first use Bentley FlowMaster, the intuitive interface and interactive dialog boxes will guide you. If you need more information, use the online help by either pressing the Help button present in each dialog box, pressing the F1 key, or rightclicking anywhere in a dialog box.

1.1

What’s New in Bentley FlowMaster? The following features are new to this release: •

Improved Tabular Reporting - You can now customize your tabular reports by selecting which columns to include, sorting and filtering data, changing column labels, and copying and pasting data to and from the Windows clipboard.

•

Customizable Report Footers - Display the date and time, company name, company logo, and other information at the bottom of all reports for a project.

•

Integration with Bentley ProjectWise - Use Bentley ProjectWise for managed

access to FlowMaster content within a workgroup, across a distributed organization, or among collaborating professionals. •

Integrated Installation and Activation - FlowMaster now prompts you to activate the software upon first use of the program.

•

Improved Cross Sections - The cross section for an Irregular Section is now plotted on a grid.

Bentley FlowMaster User’s Guide

1-1

What’s New in Bentley FlowMaster? •

Print from the Project Explorer - You can now print one or more worksheets from within the Project Explorer.

•

Improved User Interface - Toolbars can now be moved, customized, and docked to any of the four sides of the FlowMaster main window. In addition, there are new menu commands and toolbar buttons.

Previously Added to FlowMaster:

1-2

•

Gradually Varied Flow Analysis - FlowMaster can now perform gradually varied flow calculations for any free surface flow element.

•

Gradually Varied Flow Profiles - Automatically generate profile views from the calculated results of your gradually varied flow analysis.

•

New Worksheet Types - FlowMaster can now calculate parabolic channels, box pipes, and elliptical pipes.

•

Project Explorer - Work on multiple projects simultaneously and exchange data between them freely using FlowMaster's new Project Explorer.

•

Customizable Graphs - Enjoy complete control over practically every facet of your graph's appearance using the new charting module. You can even create three-dimensional graphs!

•

Project-Specific FlexUnits - Retain customized FlexUnits settings for each individual project.

•

Integrated Friction Methods - Change friction methods from each individual worksheet on-the-fly, allowing you to compare the results using any method.

•

Auto-Update - Cross Section, GVF (Gradually Varied Flow) Profile, and GVF Profile Point dialogs dynamically refresh as data is modified or added.

•

Customizable User Interface - Add and remove buttons, determine window placement, and enable or disable visibility of toolbars and other interface elements to suit your personal preferences. FlowMaster will retain your settings for future use.

•

Modeless Dialogs - Interact with multiple open windows, without having to close the active one first.

•

Multiple Concurrent Sessions - Open multiple instances of FlowMaster at the same time.

•

Cut-Copy-Paste - Use Windows-style cut, copy, and paste commands to quickly manipulate data and share it between worksheets and projects.

•

Undo/Redo - Windows-style Undo and Redo commands ease data entry tasks


Orientation

1.2

Using the Bentley FlowMaster Documentation Note:

If you cannot find the information you need, make sure you use the index or search the online book (.PDF) or online help (.CHM). These online resources contain extra information that is useful when you are actually using the software and need contextsensitive assistance or help with the software interface.

We designed the Bentley FlowMaster documentation to provide you content in the best possible way. With this in mind, there is significantly more content available online than in-print. The online content was designed to provide what you need while you are using the software, and so the online content includes information about the Bentley FlowMaster interface. The online content can also be updated dynamically as we update the software, and delivered to you by download or as part of an updated software version.

1.2.1

Minimum System Requirements We recommend the following minimum and recommended system requirements for running Bentley FlowMaster without significant delays. Processor:

Pentium III - 1 GHz

RAM:

64 Megabytes

Hard Disk:

150 Megabytes of free storage space, with additional room for data files (at least 60 MB)

Operating System:

Windows 2000, Windows XP, and Windows Vista

Display:

800 x 600 resolution, 256 colors

While Bentley Systems Haestad Methods products will perform adequately given the minimum system requirements, performance will only improve with a faster system. Our products are designed to perform at optimal levels with a fast CPU and ample amounts of RAM and free disk space. We highly recommend running our software on the best system possible to maximize its potential.


1-3

Using the Bentley FlowMaster Documentation

Municipal License Administrator Auto-Configuration At the conclusion of the installation process, the Municipal License Administrator will be executed, to automatically detect and set the default configuration for your product, if possible. However, if multiple license configurations are detected on the license server, you will need to select which one to use by default, each time the product starts. If this is the case, you will see the screen below. Simply press OK to clear the Warning dialog, then press Refresh Configurations to display the list of available configurations. Select one and press Make Default, then exit the License Administrator. (You only need to repeat this step if you decide to make a different configuration the default in the future.

Software Updates via the Web and Bentley SELECT Bentley SELECT is the comprehensive delivery and support subscription program that features product updates and upgrades via Web downloads, around-the-clock technical support, exclusive licensing options, discounts on training and consulting services, as well as technical information and support channels. It’s easy to stay up-todate with the latest advances in our software. Software updates can be downloaded from our Web site, and your version of Bentley FlowMaster can then be upgraded to the current version quickly and easily. Just click Check for Updates on the toolbar to launch your preferred Web browser and open our Web site. The Web site automatically checks to see if your installed version is the latest available, and if not, it provides you with the opportunity to download the correct upgrade to bring it up-todate. You can also access our KnowledgeBase for answers to your Frequently Asked Questions (FAQs). Note:

Your PC must be connected to the Internet to use the Check for Updates button.

Troubleshooting Due to the multitasking capabilities of Windows, you may have applications running in the background that make it difficult for software setup and installations to determine the configuration of your current system. Try these steps before contacting our technical support staff 1. Shut down and restart your computer. 2. Verify that there are no other programs running. You can see applications currently in use by pressing Ctrl+Shift+Esc in Windows 2000 and Windows XP. Exit any applications that are running. 3. Disable any antivirus software that you are running.

1-4


Orientation Caution:

After you install Bentley FlowMaster, make certain that you restart any antivirus software you have disabled. Failure to restart your antivirus software leaves you exposed to potentially destructive computer viruses.

4. Try running the installation or uninstallation again (without running any other program first). If these steps fail to successfully install or uninstall the product, contact Technical Support.

Checking Your Current Registration Status After you have registered the software, you can check your current registration status by opening the About... box from within the software itself. To view your registration information 1. Select Help > About Bentley FlowMaster. 2. The version and build number for Bentley FlowMaster display in the lower-left corner of the About Bentley FlowMaster dialog box. The current registration status is also displayed, including: user name and company, serial number, license type and check-in status, feature level, expiration date, and SELECT Server information.

1.1

How Do I?—Frequently Asked Questions “How Do I?” is an easily referenced topic in Bentley FlowMaster’s online help. It is a listing of commonly asked questions about Bentley FlowMaster. To use How Do I?, click Help > How Do I? The listing of How Do I? topics appear. Click the topic of your choice for a detailed explanation.

1.2

Glossary The glossary contains many terms used throughout the application and the online help. To use the Glossary: •

Click Help > Contents to open the main Help window.

•

Click the Contents tab, scroll to the bottom of the bookmarks list, and click the Glossary bookmark.


1-5

Contacting Bentley Systems about Haestad Methods Products

1.3

Contacting Bentley Systems about Haestad Methods Products Contact Bentley Systems if you want information about Haestad Methods products, to upgrade your Haestad Methods product, or need support.

1.3.1

•

“Sales” on page 1-6

•

“Technical Support” on page 1-6

•

“Addresses” on page 1-7

•

“Your Suggestions Count” on page 1-8

Sales Bentley Systems’ professional staff is ready to answer your questions. Please contact your sales representative with any questions regarding Haestad Methods products and prices. Phone:

+1-203-755-1666

Fax:

+1-203-597-1488

Email:

[email protected]

RELATED TOPICS

1.3.2

•

See “Technical Support” on page 6.

•

See “Addresses” on page 7.

Technical Support We hope that everything runs smoothly, and you never have a need for our technical support staff. However, if you do need support, our highly-skilled staff offers their services seven days a week and may be contacted by phone, fax, and the Internet. For information on the various levels of support that we offer, contact our sales team and request information about our Bentley SELECT program. When calling for support, in order to assist our technicians in troubleshooting your problem, please be in front of your computer and have the following information available: •

1-6

Operating system your computer is running (Windows 98, Windows ME, Windows NT, Windows 2000, or Windows XP).


Orientation •

Name and build number of the Bentley Systems software you are calling about. The build number can be determined by clicking Help > About Bentley FlowMaster. The build number is the number in brackets located in the lower-left corner of the dialog box that opens.

•

A note of exactly what you were doing when you encountered the problem.

•

Any error messages or other information displayed on your screen.

When emailing or faxing for support, please provide additional details as follows so we can provide a timely and accurate response: •

Company name, address, and phone number

•

A detailed explanation of your concerns

•

The HAESTAD.LOG and ERROR.LOG files located in the product directory RELATED TOPICS •

See “Sales” on page 6.

•

See “Addresses” on page 7.

•

See “Support Hours” on page 7.

Support Hours Support is available 24 hours a day, seven days a week. You can contact our technical support team at:

1.3.3

Phone:

+1-203-755-1666

Fax:

+1-203-597-1488

Email:

[email protected]

Addresses Use this address information to contact us: Internet:

http://www.haestad.com

Email:

[email protected] [email protected] [email protected]

Phone:

+1-203-755-1666

Fax:

+1-203-597-1488

Mail:

Bentley Systems, Incorporated


1-7

Contacting Bentley Systems about Haestad Methods Products Haestad Methods Solution Center Suite 200W 27 Siemon Company Drive Watertown, CT 06795

1.3.4

Your Suggestions Count At Bentley Systems, we strive to continually provide you with sophisticated software and documentation. We are very interested in hearing your suggestions for improving our products, our online help system, and our printed manuals. Your feedback will guide us in developing products that will make you more productive. Please let us hear from you!

1-8


Chapter

2

Tutorials

Bentley FlowMaster is an easy-to-use, Windows-based program that aids civil engineers with the design and analysis of pipes, ditches, open channels, weirs, and more. Bentley FlowMaster computes flows, water velocities, depths and pressures based on several well-known formulas: Darcy-Weisbach, Manning’s, Kutter’s, and Hazen-Williams. It also utilizes the HEC-22 methodology to perform pavement drainage and inlet flow calculations. Bentley FlowMaster lets you solve for a variable you select, computing the solution from the parameters you provide. The program will also calculate rating tables, and will plot curves and cross sections. These graphs and reports can then be viewed on the screen, copied to the Windows clipboard, saved to a file, or printed on any standard printer. These tutorials provide step-by-step instructions for creating a project, entering data in a worksheet, and generating reports.

2.1

Overview The purpose of this section is to provide step-by-step tutorials to get you familiar with some of the features and capabilities of Bentley FlowMaster. The tutorials serve as a means to get you started exploring and using the software. Note:

You should follow these tutorials in sequence.

If you need help within the program, press F1 to access the context-sensitive online help.

2.2

Tutorial 1—Creating a New Project Data is entered and calculated in a worksheet. There are different worksheets for various structure types, because of the differing input and output data that is required for each.


2-9

Tutorial 1—Creating a New Project Worksheets are contained within an Bentley FlowMaster project. A project holds global information such as Project Engineer, Project Date, Project Location (the location where the project files are stored on your computer), and any Notes that go along with the project. The project is also associated with a unit system (FlexUnits). The unit system defines the units and display precision used in the project. Upon project creation, the default unit system is used, but this can be modified and saved for use on future projects. 1. Start Bentley FlowMaster by double-clicking the shortcut on your desktop or by clicking the Bentley FlowMaster command from the Start menu. 2. When Bentley FlowMaster opens, the welcome dialog box appears. Click the Create New Project button.

3. The main window opens, with the new project loaded.

2-10


Tutorials 4. Click File > Save As. The Save As dialog box opens. 5. Choose the directory to which the file will be saved and type MyTutorial1 as the name for the project file. Note:

We recommend you name the tutorial files you are using differently than any other files in your program directory, so you don’t overwrite pre-existing files.

6. Now, enter some global project information. Click File > Properties. 7. In the Project Properties dialog box, note the types of information. The Project Date field should already contain today’s date (this information is retrieved from the Windows system calendar and clock—click the down-arrow button to select a different date by using a calendar). Project File Name contains the path to the directory where the project is saved. 8. Enter the following information in the Project Properties dialog box: –

Enter your name in the Project Engineer field.

–

Enter Tutorial Project in the Project Notes field.

–

If you want your company name to appear on the bottom of all reports associated with the project, enter the company name in the Project Company field.

–

If you want your company’s logo to appear on the bottom of all reports associated with the project, click in the Company Logo field, then click the Ellipses button and select your company’s logo image file.

–

Click OK.

9. Click File > New > Worksheet. 10. In the Create New Worksheet dialog box, ensure that Open Channels is highlighted in the Categories pane, then click Trapezoidal Channel.


2-11

Tutorial 1—Creating a New Project

11. Click OK. 12. In the Trapezoidal Channel Worksheet dialog box, select Discharge in the Solve For drop-down list. 13. Select Manning Formula in the Friction Method drop-down list.

14. In the Roughness Coefficient field, click the Ellipsis (...) button to open the Materials library. a. Expand the tree containing all of the available material libraries. b. Expand the HMI Material Library item to see the available materials within the library. c. Click Flood plain, cultivated to highlight it.

2-12


Tutorials Note that the lower section of the Materials dialog box is updated with the data that is associated with this material. d. Click OK; the Materials dialog box closes and a roughness coefficient of 0.035 displays in the Roughness Coefficient field. 15. Click each of the other input fields in turn and enter the data contained in the following table into the appropriate input fields: Table 2-1: Input Data for Trapezoidal Worksheet (Tutorial 1) Attribute:

Value:

Channel Slope

0.004500 ft/ft

Normal Depth

2.30 ft

Left Side Slope

0.50 H:V

Right Side Slope

0.75 H:V

Bottom Width

5.00 ft

The calculated discharge should be 53.21 ft3/sec. Note:

After you enter the last data into a field (Bottom Width, for example), you have to click in another field or click the Solve button to get the Discharge to refresh and update.

16. Save the project by clicking File > Save As. 17. Enter MyTutorial2 in the File name field, then click Save. 18. If needed, close any open dialog boxes.


2-13

Tutorial 2—Gradually Varied Flow Analysis

2.3

Tutorial 2—Gradually Varied Flow Analysis For free-surface flow, depth rarely remains the same throughout the length of a channel or pipe. Gradually varied flow analysis lets you calculate the downstream depth from the length of the channel and the upstream depth, or to calculate the upstream depth from the length of the channel and the downstream depth. This tutorial is based on the project that was created in “Tutorial 1—Creating a New Project” on page 2-9. 1. If necessary, open the MyTutorial2 project file that you saved at the end of Tutorial1, and, in the Project Explorer, double-click the Trapezoidal Channel item to open the worksheet containing the channel you defined in Tutorial 1. 2. In the Trapezoidal Channel Worksheet dialog box, click the Gradually Varied Flow tab.

2-14


Tutorials

a. If needed, click the Direction drop-down list and select Given Downstream. This drop-down list lets you choose whether you are solving for upstream depth (when Given Downstream is selected) or downstream depth (when Given Upstream is selected). b. Click each of the other input fields in turn and enter the data contained in the following table into the appropriate input fields: Table 2-2: Input Data for Gradually Varied Flow Analysis (Tutorial 2) Attribute

Value

Downstream Depth

3.0 ft

Length

100 ft

Number of Steps

5

c. Click Solve. The calculated downstream depth should be 2.74 ft.


2-15

Tutorial 2—Gradually Varied Flow Analysis

3. View the profile of the gradually varied flow analysis: Click Analysis > GVF Profile.

4. Save the project by clicking File > Save As. 5. Enter MyTutorial3 in the File name field, and click Save. 6. If needed, close any open dialog boxes.

2-16


Tutorials

2.4

Tutorial 3—Results Reporting Bentley FlowMaster provides a number of methods of generating reports from your calculated results. This tutorial introduces you to these methods. This tutorial is based on the project that was used in “Tutorial 2—Gradually Varied Flow Analysis” on page 2-14. 1. If necessary, open the MyTutorial3 project file that you saved at the end of Tutorial 2, and, in the Project Explorer, double-click the Trapezoidal Channel item to open the worksheet containing the channel you defined in Tutorial 2. 2. Click Analysis > Detailed Report. 3. In the Generic Report Setup dialog box, change the default report title then click OK, or click OK to accept the default report title “Worksheet for Trapezoidal Channel.” 4. The Print Preview dialog box opens, displaying the report as it would appear if printed. Note the information supplied in the report: Project Information, Input Data, Results, GVF Input Data, and GVF Output Data. 5. Close the Print Preview dialog box.


2-17

Tutorial 3—Results Reporting

6. Click Analysis > Tabular Reports > Channels > Trapezoidal.

7. The Report Table dialog box that opens presents all calculation messages, notes, input data, and results for all of the trapezoidal channel worksheets within the project; in this case, just one.

2-18


Tutorials This report is useful for comparing multiple worksheets of the same type. If you want to print this report, begin by clicking the Print Preview button. 8. Close the Report Table dialog box. 9. Click Analysis > Cross Section. Note:

If Analysis > Cross Section is dimmed, click the Solve button, then try the menu item again.

10. In the Cross Section Setup dialog box, enter Trapezoidal Channel as the Report Title, and click OK.

11. The Cross Section dialog box displays a cross section diagram defined by the trapezoidal channel worksheet. You can print the cross section by using the Print Preview button, then clicking the Print button in the Print Preview window.

12. To change the size of the diagram: a. Click the Options button. b. Select the Manual Scale check box.


2-19

Tutorial 3—Results Reporting c. Enter new value in the Aspect Ratio field, such as 3, and click OK. The diagram changes to reflect the aspect ration you entered. d. Change the Aspect Ratio back to 1. e. Close the Cross Section dialog box. 13. Bentley FlowMaster also lets you graph a range of results that are calculated from a range of values for a specified variable via the rating curves feature. a. If necessary, close any open Print and Print Preview dialog boxes and open the Trapezoidal Channel Worksheet dialog box. b. Click Analysis > Rating Curve. c. In the Rating Curve Setup dialog box, select Velocity in the Plot drop-down list. This is the attribute for which a range of values will be calculated. d. Select Channel Slope in the Vs. drop-down list; this sets the attribute against which the Plot attribute is calculated. e. Enter the information contained in the following table for the other fields in the Rating Curve Setup dialog box:

f.

2-20

-

Minimum: 0.0030 ft/ft

-

Maximum: 0.0060 ft/ft

-

Increment: 0.0005 ft/ft

Click OK. The Rating Curve dialog box opens, showing a graph of the velocity at each of the slopes in the range that is specified by the values you entered.


Tutorials

14. You can change practically any aspect of the graph’s appearance by clicking the Chart Options button.


2-21


a. Experiment with the various settings available to you. To create the 3D chart shown here:

a. Click Chart Options > 3D. b. Select the 3 Dimensions check box. c. Set the 3D % to 90. d. Click the Walls tab. e. Click the Bottom tab, then click Color.

2-22


Tutorials f.

Set the bottom color (in the example it has an Red, Green, Blue (RGB) value of 0, 255, 255).

g. Click the Panel, then Background tabs. h. Click the Pattern, Gradient, then Format tabs. i.

Select Vertical from the Direction drop-down list.

j.

Click the Colors tab.

k. Click Start. l.

Click Custom and set an RGB value of 255, 215, 0.

m. Click OK > OK to close the color dialog boxes. n. Click End. o. Select white from the Color Editor dialog box (RGB of 255, 255, 255). p. Click OK. q. In the Hatch Brush Editor dialog box, select the No Middle Color check box. r.

Click OK, then Close.

15. You can print the chart by clicking the Print Preview button, then clicking the Print button in the Print Preview window, or redefine the rating curve settings by clicking the Define Rating Curve button. 16. Save the project, then close all the open windows.


2-23


2-24


Chapter

3

Bentley FlowMaster Environment The Bentley FlowMaster interface utilizes dockable windows and toolbars, so the position of the various interface elements can be manually adjusted to suit your preference. By default, the Bentley FlowMaster environment looks like this:

The components that make up the Bentley FlowMaster interface are as follows: •

“Main Window”

•

“Project Explorer”

•

“Engineering Library Explorer”

•

“Menus”

•

“Toolbars”

Any changes you make to the placement and display of the dockable windows and toolbars will be saved, and will persist every time Bentley FlowMaster is started


3-25

Welcome Dialog Box

3.1

Welcome Dialog Box The Welcome dialog box appears upon startup of the application. The following controls are available:

3.2

Create New Project:

This button lets you create a new Bentley FlowMaster project. When you click Create New Project, a new untitled project is created. The first time the project is saved, you can specify a name for the project.

Create Worksheet:

This button opens the Create New Worksheet dialog box, letting you quickly create a worksheet that is not associated with a particular project.

Open Existing Project:

This button lets you open a previously created project.

Show This Dialog at Start:

This check box lets you display the Welcome dialog box when ever your start Bentley FlowMaster. Show This Dialog at Start is selected by default. Deselecting this check box causes Bentley FlowMaster to start up at the main window without opening the Welcome dialog box.

Main Window The Bentley FlowMaster main window is the workspace in which various project worksheets are displayed. The main window itself does not contain any controls. You can manually position the project worksheets anywhere in the workspace, or use the Window menu controls to automatically position them in a number of ways.

3.3

Project Explorer The Project Explorer window displays project components in a hierarchical tree view. Data is entered and calculated in a worksheet. There are different worksheets for various structure types, because of the differing input and output data that is required for each. Worksheets are contained within an Bentley FlowMaster project. A project holds global information such as Project Engineer, Project Date, Project Location (the location where the project files are stored on your computer), and any Notes that go along with the project.

3-26


Bentley FlowMaster Environment You can also create folders within a project. These folders can be used to organize your worksheets within the project. The folders are contained solely within the project—new Windows directories will not be created when you create folders in the Project Explorer. The project is also associated with a unit system (FlexUnits). The unit system defines the measurement and display precision used in the project. Upon project creation, the default unit system is used, but you can modify unit system and save it for use on future projects. Each worksheet in the project is represented by an icon that indicates the worksheet element type and an automatically generated label. Various commands are made accessible in the Project Explorer through the use of shortcut menus. Right-clicking a Project icon in the tree view will open a shortcut menu containing the following commands: •

Add—Hovering the mouse over this command opens a submenu containing the following commands: –

New Worksheet—This command opens the Create New Worksheet dialog box, letting you create a new worksheet.

–

New Folder—This command creates a new folder under the current project, letting you organize your project elements.

•

Properties—This command opens the Project Properties dialog box, letting you view and modify basic project information such as date, engineer, location, and notes.

•

Save—This command saves the current project.

•

Save As—This command saves all currently open projects.

•

Close Project—Closes the currently open project.

Right-clicking a worksheet within a project in the Project Explorer will open a shortcut menu containing the following commands: •

Rename—This command lets you rename the currently highlighted worksheet.

•

Delete—This command deletes the currently highlighted worksheet from the library.

•

Duplicate—This command creates a copy of the currently highlighted worksheet in the same project.

•

Print—This command prints a report of the currently highlighted worksheet. When you click this command, you are prompted to enter the title for the report.


3-27

Engineering Library Explorer •

3.3.1

Print Selected Worksheets—This command lets you print more than one worksheet at a time and is only available when multiple worksheeets are selected in the Project Explorer. To use this command, first select the first worksheet to print, then Ctrl+click or Shift+click the additional worksheets you want to print. Rightclick and select Print Selected Worksheets.

Project Files Bentley FlowMaster projects comprise the following files: Note:

When transferring an Bentley FlowMaster project, make sure that these files are present, or you will not be able to open it.

Projectname.fm8:

This file holds all of the project settings.

Projectname.fm8.mdb:

This is a database file that holds all of the input and output data for the project. When emailing or otherwise transferring .mdb files, it is a good idea to compress them using WinZip or another compression utility—the file size will generally be reduced drastically.

Other files that you may encounter in your saved file directories include:

3.4

Projectname.fm8.01.bak:

This file is a backup file for the FlowMaster project settings file.

Projectname.fm8.mdb.01.bak:

This file is a backup file for the FlowMaster data database file.

Projectname.fm8.mdb.ldb:

This file is a database lock file. It will be automatically generated when a project database is currently open, and it prevents changes from being made directly to the database. This prevents data loss and corruption.

Engineering Library Explorer The Engineering Library Explorer contains all of the project’s material libraries. Individual material libraries are compilations of all available materials, and their attributes. Click View > Engineering Library to see the library. You cannot modify the default material library that is installed with Bentley FlowMaster. However, you can create a new library that contains any materials that you define.

3-28


Bentley FlowMaster Environment Each library is represented by an icon in the explorer view, and each material under the library is represented by another icon. Right-click a Project icon in the Project Explorer to open a shortcut menu containing the following commands: •

Add—Hover the mouse over this command to open a submenu containing the following commands: –

Material—This command creates a new material entry in the current library.

–

Folder—This command creates a new folder under the current library, letting you organize your materials within the library.

•

Delete—This command deletes the current library from the current project.

•

Rename—This command lets you rename the current library.

Right-click a material icon in the tree view to open a shortcut menu containing the following commands:

3.5

•

Add—This command creates a new material within the current library.

•

Delete—This command deletes the currently highlighted material from the library.

•

Rename—This command lets you rename the currently highlighted material.

•

Properties—This command lets you modify the attribute values for the currently highlighted material.

Menus FlowMaster’s drop-down menu system provides access to all PondPack's tools and data managers. The menu system consists of the following selections: •

“File Menu”

•

“Edit Menu”

•

“Analysis Menu”

•

“View Menu”

•

“Tools Menu”

•

“Window Menu”

•

“Help Menu”


3-29

Menus

3.5.1

File Menu The File menu contains project management commands. It provides features to create, read, write, and print project files. •

New—This command opens a submenu containing the following options: –

Project—This command creates a new Bentley FlowMaster project. Initiating this command opens a dialog box that lets you enter a drive, directory, and filename for your new project file.

–

Worksheet—This command opens the Create New Worksheet dialog box, letting you create a new worksheet within the current project.

•

Open—This command opens an existing Bentley FlowMaster project. Initiating this command opens a dialog box that lets you choose the project file that you want to open.

•

Close—This command closes the project that is currently highlighted in the Project Explorer, without closing Bentley FlowMaster.

•

Close All—This command closes all open projects without closing FlowMaster.

•

Save—This command saves the current project.

•

Save As—This command lets you save the current project under a different filename and/or to a different directory.

•

Save All—This command saves all currently open projects.

•

ProjectWise—This command opens a submenu containing the following

commands:

3-30

–

Open—Open an existing FlowMaster project from ProjectWise. You are prompted to log into a ProjectWise datasource if you are not already logged in.

–

Save As—Saves the current project to a ProjectWise datasource. You are prompted to log into a ProjectWise datasource if you are not already logged in.

–

Change Datasource—Lets you connect to a different ProjectWise datasource for future Open and Save As operations.

•

Print Setup—This command lets you define the print settings that will be used when the current view of the project is printed.

•

Print Preview—This command displays what a printout of the project would look like. When you click this button, you are prompted to enter the title for the report.

•

Print—This command prints the current view of the project.


Bentley FlowMaster Environment

3.5.2

•

Properties—This command opens the Project Properties dialog box, letting you view and edit the project date, engineer, file name, and any notes associated with the project.

•

Recent Projects—This command displays a list of all recently opened projects.

•

Exit—This command closes Bentley FlowMaster. If you have any open projects that need saving, you are prompted to save them.

Edit Menu The Edit menu lets you use time-saving shortcuts such as undo/redo and cut-copypaste.

3.5.3

•

Undo—This command cancels last data input action on the current worksheet. Clicking Undo again cancels the second-to-last data input action, and so on.

•

Redo—This command cancels the last Undo command.

•

Cut—This command removes the currently highlighted field data and places it on the Windows clipboard. From the clipboard, you can paste the data into another field.

•

Copy—This command copies the currently highlighted field data and places it on the Windows clipboard. From the clipboard, you can paste the data into another field

•

Paste—This command pastes the data stored in the Windows clipboard into the currently highlighted field.

•

Copy Worksheet Data—This command copies the input data from the currently active worksheet.

•

Duplicate Worksheet—This command creates a copy of the current worksheet, including all input data.

•

Delete—This command deletes the current selection.

Analysis Menu The Analysis menu provides access to various analytical tools that allow you to generate reports, rating tables and curves, and gradually varied flow profiles. •

Detailed Report—This command opens a report that contains project information, input data, and calculated results.

•

Rating Table—This command opens the Rating Table Setup dialog box, where you define a rating table to be associated with the current worksheet.


3-31

Menus

3.5.4

•

Rating Curve—This command opens the Rating Curve Setup dialog box, letting you define the parameters that will define the content and appearance of the rating curve plot.

•

Cross Section—This command opens the Cross Section Setup dialog box, letting you enter a title for the cross section and to change the scale, if desired.

•

GVF Profile—This command opens a dialog box displaying a diagram of the worksheet element’s cross section. More information about the various profile types can be found in “Profile Classification” on page 5-149.

•

GVF Profile Table—This command opens a report displaying the results of the gradually varied flow calculations in tabular format.

•

Tabular Reports—This command opens a submenu that lets you select tabular reports displaying input and results for the chosen worksheet.

View Menu The View menu lets you activate/deactivate the component windows of the Bentley FlowMaster interface.

3-32

•

Project Explorer—This command toggles on/off the display of the Project Explorer window.

•

Engineering Library Explorer—This command toggles on/off the display of the Engineering Library Explorer window.

•

Status Bar—This command toggles on/off the display of the status bar. A check mark appears next to this command when the status bar is displayed.

•

Toolbars—This command opens a submenu containing the following options: –

Standard—This command toggles on/off the display of the standard toolbar. A check mark appears next to this command when the standard toolbar is displayed.

–

Edit—This command toggles on/off the display of the edit toolbar. A check mark appears next to this command when the edit toolbar is displayed.

–

Help—This command toggles on/off the display of the help toolbar. A check mark appears next to this command when the help toolbar is displayed.

–

Analysis—This command toggles on/off the display of the analysis toolbar. A check mark appears next to this command when the analysis toolbar is displayed

–

Worksheets—This command toggles on/off the display of the worksheets buttons. A check mark appears next to this command when the worksheets toolbar is displayed.


Bentley FlowMaster Environment •

3.5.5

Reset Workspace—Resets the FlowMaster workspace so that the Project Explorer and Engineering Library Explorer appear in their default factory-set positions.

Tools Menu The Tools menu contains a command that let you modify some project-level settings. •

3.5.6

Options—This command opens the Options dialog box, letting you view and edit unit settings associated with the project, and edit ProjectWise settings.

Window Menu The Window menu provides commands that allow you to alter the position of the various worksheets within the Bentley FlowMaster window.

3.5.7

•

Cascade—This command causes the worksheets in the main window to overlap one another in an offset way that maintains visibility of each. Note that this command maximizes all worksheets in the main window.

•

Tile Horizontally—This command causes the worksheets in the main window to overlap one another horizontally such that each is at least partially visible. Note that this command maximizes all worksheets in the main window.

•

Tile Vertically—This command causes the worksheets in the main window to overlap one another vertically such that each is at least partially visible. Note that this command maximizes all worksheets in the main window.

•

Minimize All—This command minimizes all of the worksheets in the main window.

•

Close All—This command closes all of the worksheets in the main window.

•

Window List—This command displays a list of all open windows.

Help Menu The Help menu provides access to the Bentley FlowMaster documentation, maintenance tools, and other resources. •

Dynamic Help—This command opens the online help to the topic associated with the currently active window.

•

Contents—This command opens the Table of Contents view in the online help.

•

Index—This command opens the online help’s index of key words.


3-33

Toolbars

3.6

•

Search—This command lets you search the online help for a specified word or phrase.

•

Release Notes—This command opens the online help to describe the new features in this release of Bentley FlowMaster.

•

Services—This command Opens a sub-menu containing the following options: –

Contents—Opens your browser to the Services page of our Web site.

–

Multimedia CD—Starts the Virtual Tour, a multimedia presentation that includes information about Haestad Methods products and services.

–

On-Line Forums—Opens your browser to the online forums page of the www.Haestad.com Web site.

–

Haestad.com—Opens your browser to the main page of the our Web site.

–

CivilQuiz.com—Opens your browser to the CivilQuiz.com Web site.

•

Welcome Dialog—This command opens the Welcome dialog box.

•

Tutorials—This command accesses the interactive tutorials, which guide you through many of the program’s features. Tutorials are a great way to become familiar with new features (for more information, see “Tutorials” on page 2-9).

•

Using Bentley FlowMaster—This opens the How Do I section of the online help, providing assistance with frequently used functions.

•

How Do I?—This command opens help to a series of frequently-asked questions.

•

Check for Updates—Lets you update your software via the World Wide Web. For more information, “Contacting Bentley Systems about Haestad Methods Products” on page 1-6.

•

About Bentley FlowMaster—This command opens a window containing the product and registration information for Bentley FlowMaster.

Toolbars Bentley FlowMaster has four toolbars:

3-34

•

“Standard Toolbar”

•

“Analysis Toolbar”

•

“Worksheets Toolbar”

•

“Edit Toolbar”

•

“Help Toolbar”



Standard Toolbar

Edit Toolbar

Help Toolbar

Analysis Toolbar

Worksheets Toolbar

3.6.1

Customizing Toolbars You can add and remove buttons to any toolbar. Click the down arrow on the end of the toolbar you want to customize, click Add or Remove Buttons, then click the toolbar button you want to add or remove. A check mark appears next to the toolbar buttons that are currently displayed.


3-35

Toolbars You can move the menu bar and any toolbar to any position in the FlowMaster main window. To move the menu bar or a toolbar, move your mouse to the vertical dotted line on the left side of any toolbar until the cursor changes to a crosshairs, then drag the toolbar to the desired location. If you move a toolbar away from the other toolbar, the toolbar becomes a floating dialog box.

If you move the menu bar or a toolbar to any of the four sides of the main window, the toolbar will dock or attach to the window in that location.

3.6.2

Standard Toolbar The standard toolbar contains the following buttons: •

3.6.3

New—Click this button to open a submenu containing the following options: –

Project—This command creates a new Bentley FlowMaster project. Initiating this command opens a dialog box that lets you enter a drive, directory, and filename for your new project file.

–

Worksheet—This command opens the Create New Worksheet dialog box, letting you create a new worksheet within the current project.

•

Open—This button opens an existing Bentley FlowMaster project. Initiating this command opens a dialog box that lets you choose the project file that you want to open.

•

Save—This button saves the current project.

•

Save All—This button saves all currently open projects.

•

Print—This button prints the current view of the project.

•

Print Preview—This button displays what a printout of the project would look like. When you click this button, you are prompted to enter the title for the report.

•

Toolbar Options—Click this arrow at the end of the toolbar to add or remove buttons.

Analysis Toolbar The analysis toolbar contains the following buttons: •

3-36

Tabular Reports—This command opens a tabular report displaying input and results for the chosen worksheet.



3.6.4

•

Detailed Report—This command opens a report that contains project information, input data, and calculated results.

•

Rating Table—This command opens the Rating Table Setup dialog box, where you define a rating table to be associated with the current worksheet.

•

Rating Curve—This command opens the Rating Curve Setup dialog box, where you define the parameters that will define the content and appearance of the rating curve plot.

•

Cross Section—This command opens the Cross Section Setup dialog box, where you enter a title for the cross section and to change the scale, if desired.

•

GVF Profile—This command opens a dialog box displaying a diagram of the worksheet element’s cross section.

•

GVF Profile Table—This command opens a report displaying the results of the gradually varied flow calculations in tabular format.

•


Worksheets Toolbar The Worksheets toolbar buttons let you access worksheets for: •

Open channels

•

Pipes

•

Weirs

•

Orifices

•

Inlets

The Worksheets toolbar also contains the following control: •

3.6.5


Edit Toolbar The Edit toolbar contains the following buttons: •

Cut—This button removes the currently highlighted field data and places it on the Windows clipboard. From the clipboard, you can paste the data into another field.

•

Copy—This button copies the currently highlighted field data and places it on the Windows clipboard. From the clipboard, you can paste the data into another field


3-37

Create New Worksheet

3.6.6

•

Paste—This button pastes the data stored in the Windows clipboard into the currently highlighted field.

•

Undo—This button cancels last data input action on the current worksheet. Clicking Undo again cancels the second-to-last data input action, and so on.

•

Redo—This button cancels the last Undo command.

•


Help Toolbar The Help toolbar provides easy access to commonly used documentation and help resources.

3.7

•

Check for Updates—This button lets you update your software via the World Wide Web.

•

Contents—This button opens the online help to the Table Of Contents view.

•

Dynamic Help—This button opens the online help for the currently active window or worksheet.

•


Create New Worksheet This dialog box lets you choose the type of worksheet dialog box to create. The left pane of the window displays the five worksheet categories, and the right pane shows the individual element types under the category. Click a category in the left pane, then click the desired worksheet type and click OK. The available categories are as follows: •

3-38

Open Channels—The Open Channels category includes the following worksheet types: –

Rectangular Channel

–

Triangular Channel

–

Trapezoidal Channel

–

Gutter Channel

–

Irregular Section

–

Parabolic Channel



•

•

•

Pipes—The Pipes category includes the following worksheet types: –

Pressure Pipe

–

Circular Pipe

–

Box Pipe

–

Elliptical Pipe

–

Irregular Section

Weirs—The Weirs category includes the following worksheet types: –

Rectangular Weir

–

V-Notch Weir

–

Cipolletti Weir

–

Broad Crested Weir

–

Generic Weir

Orifices—The Orifices category includes the following worksheet types: –

Rectangular Orifice

–

Circular Orifice

–

Generic Orifice

Inlets—The Inlets category includes the following worksheet types: –

Grate Inlet in Sag

–

Grate Inlet on Grade

–

Curb Inlet in Sag

–

Curb Inlet on Grade

–

Ditch Inlet in Sag

–

Ditch Inlet on Grade

–

Slotted Drain Inlet in Sag

–

Slotted Drain Inlet on Grade

–

Combination Inlet in Sag

–

Combination Inlet on Grade


3-39

Channel Worksheet Dialog Boxes

3.8

Channel Worksheet Dialog Boxes The following channel worksheet dialog boxes are available:

3.8.1

•

“Rectangular Channel Dialog Boxes”

•

“Triangular Channel Dialog Box”

•

“Trapezoidal Channel Dialog Box”

•

“Gutter Section Dialog Box”

•

“Irregular Section Dialog Box”

•

“Parabolic Channel Dialog Box”

Rectangular Channel Dialog Boxes The following controls make up the Rectangular Channel worksheet dialog box: •

Solve For—This drop-down list lets you select the variable that you are solving for. The variable that is chosen will appear yellow (read-only) in the list of available input fields.

•

Friction Method—This drop-down list lets you select the friction method that will be used to calculate the worksheet. The Darcy-Weisbach method requires an additional input variable (Kinematic Viscosity) and generates additional output (Friction Factor and Reynolds Number).

•

Messages—A Messages tab is included in each worksheet. The top section of this tab displays informational calculation messages, while the bottom section lets you enter any explanatory notes that you wish to be associated with the worksheet.

This dialog box comprises the following tabs: •

“Uniform Flow Tab—Rectangular Channel”

•

“Gradually Varied Flow Tab—Rectangular Channel”

Uniform Flow Tab—Rectangular Channel The Uniform Flow tab comprises an input section on the left and an output, or results, section on the right. Input: •

3-40

Roughness Coefficient—A value used to represent the resistance of a conveyance element to flow.



Channel Slope—Longitudinal slope in the channel. Also, the vertical drop divided by the channel length.

•

Normal Depth—Distance from water surface to low point of channel bottom.

•

Bottom Width—Width of the bottom of the channel cross section.

•

Discharge—Volumetric rate of flow, given in units of length (cubed) over time.

•

Kinematic Viscosity (This input is only available when one of the Darcy-Weisbach Friction methods is used)—Viscosity divided by the mass density given in units of length (squared) over time, hence the term kinematic. Viscosity is a property measuring the fluid resistance to shear. For example, molasses and tar have relatively high viscosity and water and air relatively low viscosity.

Output: •

Flow Area—Cross-sectional area of flow.

•

Wetted Perimeter—Perimeter of flow that travels against a solid boundary. For a partially full pipe, the wetted perimeter includes all of the flow perimeter except for the top segment, which has a free surface.

•

Top Width—Length of the free top surface on the flowing cross section. For a cross section flowing full, this value is zero.

•

Critical Depth—Depth of water in the channel for which the specific energy is at its minimum. Specific Energy is the sum of the elevation head and velocity head (energy due to the velocity of a liquid) as related to the section of a channel bed.

•

Critical Slope—Channel slope for which the uniform flow (equilibrium flow for which the slope of total energy equals the channel slope) is critical.

•

Velocity—Linear measure of flow rate given in units of length over time. For weirs and orifices, the velocity field is for the velocity of the water through the hydraulic structure.

•

Velocity Head—Energy due to the velocity of a liquid.

•

Specific Energy—Sum of the elevation head and velocity head (energy due to the velocity of a liquid) as related to the section of a channel bed.

•

Froude Number—Dimensionless parameter used to characterize open channel flow. For critical flow, this value is 1.

•

Flow Type—The flow is defined as: –

Supercritical if F > 1

–

Subcritical if F < 1

–

Critical if F = 1

where F is the Froude Number.


3-41

Channel Worksheet Dialog Boxes •

Friction Factor (This output is only available when one of the Darcy-Weisbach Friction methods is used)—Friction coefficient used in the Darcy-Weisbach (Colebrook-White) Formula.

•

Reynolds Number (This output is only available when one of the Darcy-Weisbach Friction methods is used)—Ratio of viscous forces relative to inertial forces.

Gradually Varied Flow Tab—Rectangular Channel The Gradually Varied Flow tab comprises an input section on the left and an output, or results, section on the right. There is also a Direction drop-down list: •

Direction—This drop-down list lets you choose whether you are solving for the Upstream Depth or the Downstream Depth, as follows: –

Given Upstream—When you choose this option, the Upstream Depth is an input variable and the gradually varied flow analysis will solve for downstream depth.

–

Given Downstream—When you choose this option, the Downstream Depth is an input variable and the gradually varied flow analysis will solve for upstream depth.

Input: •

Downstream Depth—Distance from water surface to low point of channel bottom at the downstream end of the channel.

•

Upstream Depth—Distance from water surface to low point of channel bottom at the upstream end of the channel.

•

Length—The length of the channel.

•

Number of Steps—The number of segments per profile that the channel is divided into based on its starting and goal depth. In unbounded cases, the number of steps is used to determine the marching interval, but not as strictly as in a bounded profile. This input is required by the direct step method that is used in the gradually varied flow analysis. It is recommended that the value entered here be at least five for accuracy. Increasing this number will increase the accuracy of the hydraulic grade calculation, but will increase the calculation time.

Output: •

Profile Description—The profile classification within the channel. Note:

•

3-42

More information about the various profile types can be found in “Profile Classification” on page 5-149.

Headloss—Loss of energy due to friction and minor losses.



3.8.2

•

End Depth/Rise—Distance from water surface to low point of channel bottom at the end of the channel.

•

Normal Depth/Rise—Average distance from water surface to low point of channel bottom along the length of the channel.

•

Downstream Velocity—Linear measure of flow rate at the downstream end of the channel, given in units of length over time.

•

Upstream Velocity—Linear measure of flow rate at the upstream end of the channel, given in units of length over time.

•


•


Triangular Channel Dialog Box The following controls make up the Triangular Channel worksheet dialog box: •


•


•



“Uniform Flow Tab—Triangular Channel”

•

“Gradually Varied Flow Tab—Triangular Channel”

Uniform Flow Tab—Triangular Channel The Uniform Flow tab comprises an input section on the left and an output, or results, section on the right. Input: •



3-43



•


•

Left Side Slope—The slope along the left side of the channel.

•

Right Side Slope—The slope along the right side of the channel.

•


•


Output:

3-44

•

Flow Area—Cross sectional area of flow.

•


•


•


•


•


•


•


•


•

Profile Description—The profile classification within the channel.

•


•




Gradually Varied Flow Tab—Triangular Channel The Gradually Varied Flow tab comprises an input section on the left and an output, or results, section on the right.There is also a Direction drop-down list: •



–


Input: •


•


•


•


Output: •



•


•


•


•



3-45


3.8.3

•


•


•


Trapezoidal Channel Dialog Box The following controls make up the Trapezoidal Channel worksheet dialog box: •


•


•



“Uniform Flow Tab—Trapezoidal Channel”

•

“Gradually Varied Flow Tab—Trapezoidal Channel”

Uniform Flow Tab—Trapezoidal Channel The Uniform Flow tab comprises an input section on the left and an output, or results, section on the right. Input:

3-46

•


•


•


•

Left Side Slope—Slope of the left side of the channel.

•

Right Side Slope—Slope of the right side of the channel.

•





•


Output: •


•


•


•


•


•


•


•


•


•


•


•



3-47


Gradually Varied Flow Tab—Trapezoidal Channel The Gradually Varied Flow tab comprises an input section on the left and an output, or results, section on the right.There is also a Direction drop-down list: •



–


Input: •


•


•


•


Output: •


3-48


•


•


•


•




3.8.4

•


•


•


Gutter Section Dialog Box The Gutter Section worksheet dialog box comprises an input section on the left and an output, or results, section on the right. Additionally, a Messages tab is included in each worksheet. The top section of this tab displays informational calculation messages, while the bottom section lets you enter any explanatory notes that you wish to be associated with the worksheet. Input: •


•


•

Slope—Longitudinal slope in the channel. Also the vertical drop divided by the channel length.

•

Gutter Width—Width of the gutter (W) measured from the curb face to the break in slope of the roadway pavement.

•

Gutter Cross Slope—Slope (Sw) of the gutter, measured in the cross-sectional plane of the roadway. If the roadway section is uniform (no gutter depression), then you can leave the gutter width to 0.0 as well as the gutter cross-slope.

•

Road Cross Slope—Slope (Sx) of the road pavement, measured in the crosssectional plane of the roadway.

•

Spread—A measure of the transverse lateral distance (T) from the curb face to the limit of the water flowing on the roadway.

•

Manning’s Coefficient—Roughness coefficient used in Manning's Formula.

Output: •


•

Depth—Distance from water level to low point of channel bottom.


3-49


3.8.5

•

Gutter Depression—Used for Composite Gutter Section. This is the depth a of the gutter measured at the curb face, from the projection of the pavement crossslope at the curb face. The gutter depression applies to gutters that are continuously depressed (as opposed to local depression that applies to a depression of the gutter at the location of the inlet only).

•

Velocity—Linear measure of flow rate given in units of length over time.

Irregular Section Dialog Box The Irregular Section worksheet dialog box comprises an input section on the left and an output, or results, section on the right. The following controls make up the worksheet: •


•


•

Edit Section—Opens the Irregular Section Editor, letting you define the cross section of the irregular section.

•

Options—Opens the Weighted Roughness method dialog box, letting you define the current roughness method, open channel weighting method, and the closed channel weighting method.

•



“Uniform Flow Tab—Irregular Section”

•

“Gradually Varied Flow Tab—Irregular Section”

Uniform Flow Tab—Irregular Section The Uniform Flow tab comprises an input section on the left and an output, or results, section on the right. Input:

3-50




•

Channel Slope—Longitudinal slope in the channel. Also, the vertical drop divided by the channel length. In Irregular Sections, the vertical drop is measured from low point to low point.

•

Water Surface Elevation—Elevation of the channel's flowing surface, usually given in mean sea level (MSL).

•

Elevation Range—The minimum to maximum elevation of the Irregular Section.

•


•


Output: •


•


•


•


•

Critical Elevation—Water surface elevation (elevation of the channel's flowing surface), for critical depth (depth of water in the channel for which the specific energy is at its minimum).

•


•


•


•


•


•



3-51



•


Gradually Varied Flow Tab—Irregular Section The Gradually Varied Flow tab comprises an input section on the left and an output, or results, section on the right.There is also a Direction drop-down list: •

Direction (menu)—This drop-down list lets you choose whether you are solving for the Upstream Depth or the Downstream Depth, as follows: –


–


Input: •


•


•


•


Output: •


•

3-52





3.8.6

•


•


•


•


•


•


Parabolic Channel Dialog Box The following controls make up the Parabolic Channel worksheet dialog box: •


•


•



“Uniform Flow Tab—Parabolic Channel”

•

“Gradually Varied Flow Tab—Parabolic Channel”

Uniform Flow Tab—Parabolic Channel The Uniform Flow tab comprises an input section on the left and an output, or results, section on the right. Input: •



3-53



•

Constructed Depth—Distance from water level to low point of channel bottom.

•


•

Constructed Top Width—Cross sectional width of the channel at the highest point.

•


•


Output:

3-54

•


•


•


•


•


•


•


•


•


•



–


–

Critical if F = 1


Bentley FlowMaster Environment where F is the Froude Number. •


•


Gradually Varied Flow Tab—Parabolic Channel The Gradually Varied Flow tab comprises an input section on the left and an output, or results, section on the right. There is also a Direction drop-down list: •



–


Input: •


•


•


•


Output: •


•




3-55

Pipe Worksheet Dialog Boxes

3.9

•


•


•


•


•


•


Pipe Worksheet Dialog Boxes The available pipe worksheets are as follows:

3.9.1

•

“Pressure Pipe Dialog Box”

•

“Circular Pipe Dialog Box”

•

“Box Pipe Worksheet Dialog Box”

•

“Elliptical Pipe Section Dialog Box”

•

“Irregular Section Dialog Box”

Pressure Pipe Dialog Box The Pressure Pipe worksheet dialog box comprises an input section on the left and an output, or results, section on the right. Additionally, a Messages tab is included in each worksheet. The top section of this tab displays informational calculation messages, while the bottom section lets you enter any explanatory notes that you wish to be associated with the worksheet. Input:

3-56

•

Pressure at 1—Measured or computed pressure at section 1 in Bernoulli's Equation.

•

Pressure at 2—Measured or computed pressure at section 2 in Bernoulli's Equation.

•

Elevation at 1—Measured or computed elevation at section 1 in Bernoulli's Equation.



Elevation at 2—Measured or computed elevation at section 2 in Bernoulli's Equation.

•

Length—Distance from section 1 to section 2 measured along the channel centerline in Bernoulli's Equation.

•

Roughness Coefficient—Average height of roughness particles in the channel.

•

Diameter—The inside diameter of a circular channel.

•


•

Kinematic Viscosity—(This input is only available when one of the Darcy-Weisbach Friction methods is used)—Viscosity divided by the mass density given in units of length (squared) over time, hence the term kinematic. Viscosity is a property measuring the fluid resistance to shear. For example, molasses and tar have relatively high viscosity and water and air relatively low viscosity.

•

Specific Weight—(This input is only available when one of the Darcy-Weisbach Friction methods is used) The weight of a unit volume of a substance.

Output: •

Headloss—Loss of energy grade over a longitudinal channel distance.

•

Energy Grade at 1—Energy (total energy of flow with reference to a datum. Computed for closed channels as the sum of channel centerline height above datum, piezometric height, and the velocity head. Computed for open channels as the sum of channel invert height above datum, the flow depth, and velocity head) of flow at section 1 in Bernoulli's Equation.

•

Energy Grade at 2—Energy (total energy of flow with reference to a datum. Computed for closed channels as the sum of channel centerline height above datum, piezometric height, and the velocity head. Computed for open channels as the sum of channel invert height above datum, the flow depth, and velocity head) of flow at section 2 in Bernoulli's Equation.

•

Hydraulic Grade at 1—Hydraulic grade of flow at section 1 in Bernoulli's Equation.

•

Hydraulic Grade at 2—Hydraulic grade of flow at section 2 in Bernoulli's Equation.

•


•


•


•


•

Friction Slope—Slope of the energy grade line (sum of base elevation, velocity head, and pressure head at a section).


3-57


3.9.2

•

Friction Factor—Friction coefficient used in the Darcy-Weisbach (ColebrookWhite) Formula.

•

Reynolds Number—Ratio of viscous forces relative to inertial forces.

Circular Pipe Dialog Box The following controls make up the circular pipe worksheet dialog box: •


•


•



“Uniform Flow Tab—Circular Pipe”

•

“Gradually Varied Flow Tab—Circular Pipe”

Uniform Flow Tab—Circular Pipe The Uniform Flow tab comprises an input section on the left and an output, or results, section on the right. Input:

3-58

•


•


•


•

Diameter—The inside diameter of the circular channel.




•


Output: •


•


•


•


•

Percent Full—Used in closed channels as a measure of flow depth divided by maximum depth.

•


•


•


•


•


•

Maximum Discharge—The maximum theoretical discharge that could occur for a closed channel using a given hydraulic computation method. For closed circular channels, this discharge occurs at 0.938 * Diameter. Any increase in depth will decrease the discharge, which is why the full flow discharge is less than the maximum discharge for a circular channel.

•

Discharge Full—The computed discharge when a closed channel is flowing full.

•

Slope Full—The computed channel slope that would produce full flow.

•



3-59

Pipe Worksheet Dialog Boxes •


•


Gradually Varied Flow Tab—Circular Pipe The Gradually Varied Flow tab comprises an input section on the left and an output, or results, section on the right. There is also a Direction drop-down list: •



–


Input: •


•


•


•


Output: •


•

3-60





3.9.3

•

Conjugate Depth—Conjugate depths of flow are the depths upstream and downstream of a hydraulic jump. The upstream conjugate depth is supercrital and the downstream conjugate depth is subcritical.

•


•


•


•


•


•


Box Pipe Worksheet Dialog Box This worksheet dialog box comprises the following tabs: •

“Uniform Flow Tab—Box Pipe”

•

“Gradually Varied Flow Tab—Box Pipe”

Additionally, a Messages tab is included in each worksheet. The top section of this tab displays informational calculation messages, while the bottom section lets you enter any explanatory notes that you wish to be associated with the worksheet.

Uniform Flow Tab—Box Pipe The Uniform Flow tab comprises an input section on the left and an output, or results, section on the right. Input: •


•


•


•

Height—Height of the channel cross section.

•



3-61

Pipe Worksheet Dialog Boxes •


•


Output:

3-62

•


•


•


•


•


•


•


•


•


•


•


•


•


•


•




Gradually Varied Flow Tab—Box Pipe The Gradually Varied Flow tab comprises an input section on the left and an output, or results, section on the right. There is also a Direction drop-down list: •



–


Input: •


•


•


•


Output: •



•


•


•


•



3-63


3.9.4

•


•


•


Elliptical Pipe Section Dialog Box The elliptical pipe worksheet dialog box comprises the following tabs: •

“Uniform Flow Tab—Elliptical Pipe”

•

“Gradually Varied Flow Tab—Elliptical Pipe”


Uniform Flow Tab—Elliptical Pipe The Uniform Flow tab comprises an input section on the left and an output, or results, section on the right. Input: •


•


•


•

Rise—The height of the section.

•

Span—The width of the section.

•


•


Output: •

3-64





•


•


•


•


•


•


•


•


•


•


•


•


•


Gradually Varied Flow Tab—Elliptical Pipe The Gradually Varied Flow tab comprises an input section on the left and an output, or results, section on the right. There is also a Direction drop-down list: •

Direction—This drop-down list lets you choose whether you are solving for the Upstream Depth or the Downstream Depth, as follows:


3-65

Pipe Worksheet Dialog Boxes –


–


Input: •


•


•


•


Output: •


3-66


•


•


•


•


•


•


•




3.10

Weir Worksheet Dialog Boxes The available weir worksheets are as follows:

3.10.1

•

“Rectangular Weir Dialog Box”

•

“V-Notch Weir Dialog Box”

•

“Cipoletti Weir Dialog Box”

•

“Broad Crested Weir Dialog Box”

•

“Generic Weir Dialog Box”

Rectangular Weir Dialog Box The Rectangular Weir worksheet dialog box comprises an input section on the left and an output, or results, section on the right. Additionally, a Messages tab is included in each worksheet. The top section of this tab displays informational calculation messages, while the bottom section lets you enter any explanatory notes that you wish to be associated with the worksheet. Input: •


•

Headwater Elevation—Water elevation upstream of the structure.

•

Crest Elevation—Elevation of the bottom of the weir opening.

•

Tailwater Elevation—Water elevation downstream of the structure.

•

Discharge Coefficient—Discharge coefficient Cd used by FHWA HDS-5 methodology to account for submergence effects and reduce the discharge coefficient that would be obtained without submergence.

•

Crest Length—Length of the weir opening measured at the crest, perpendicularly to the flow direction.

•

Number of Contractions—Used when the upstream channel is larger than the rectangular weir crest length, to account for the contraction of the flow on one or both sides of the weir opening.

Output: •

Headwater Height Above Crest—Water depth upstream of the weir measured from the crest of the weir.


3-67

Weir Worksheet Dialog Boxes

3.10.2

•

Tailwater Height Above Crest—Height of the water downstream of the weir measured from the weir crest (a negative value indicated that the tailwater is below the crest elevation).

•


•

Velocity—Linear measure of flow rate given in units of length over time. For weirs, the velocity field is for the velocity of the water through the hydraulic structure

•


•


V-Notch Weir Dialog Box The V-Notch Weir worksheet dialog box comprises an input section on the left and an output, or results, section on the right. Additionally, a Messages tab is included in each worksheet. The top section of this tab displays informational calculation messages, while the bottom section lets you enter any explanatory notes that you wish to be associated with the worksheet. Input: •


•


•


•


•

V-Notch Weir Coefficient—Coefficients for V-notched weirs vary with the angle of the notch and with head depth. See “V-Notch Weir Coefficient of Discharge” on page 5-157.

•

Notch Angle—Angle of the V-Notch weir opening measured from one side to the other side.

Output:

3-68

•


•




3.10.3

•


•


•


•


Cipoletti Weir Dialog Box The Cipoletti Weir worksheet dialog box comprises an input section on the left and an output, or results, section on the right. Additionally, a Messages tab is included in each worksheet. The top section of this tab displays informational calculation messages, while the bottom section lets you enter any explanatory notes that you wish to be associated with the worksheet. Input: •


•


•


•


•

Discharge Coefficient—Weir coefficient obtained from experimental data, dependent on the shape of the weir.

•


Output: •


•


•

Equal Side Slopes—Slope of trapezoidal channel, assumed to be identical on both sides.

•



3-69

Weir Worksheet Dialog Boxes

3.10.4

•


•


•


Broad Crested Weir Dialog Box The Broad Crested Weir worksheet dialog box comprises an input section on the left and an output, or results, section on the right. Additionally, a Messages tab is included in each worksheet. The top section of this tab displays informational calculation messages, while the bottom section lets you enter any explanatory notes that you wish to be associated with the worksheet. Input: •


•


•


•


•

Crest Surface Type—Surface of a broad crested weir, defined as Paved or Gravel. Used by FHWA HDS-5 methodology for calculating the discharge coefficient and submergence factor.

•

Crest Breadth—Width (Lr) of the weir, measured in the direction of flow.

•


Output:

3-70

•


•


•

Discharge Coefficient—Weir coefficient obtained from experimental data, dependent on the shape of the weir.



3.10.5

•

Submergence Factor—Ratio (kt) used by FHWA HDS-5 methodology for calculating the submergence effect and reduce the discharge coefficient.

•

Adjusted Discharge Coefficient—Discharge coefficient (Cd) used by FHWA HDS-5 methodology to account for submergence effects and reduce the discharge coefficient that would be obtained without submergence.

•


•


•


•


Generic Weir Dialog Box The Generic Weir worksheet dialog box comprises an input section on the left and an output, or results, section on the right. Additionally, a Messages tab is included in each worksheet. The top section of this tab displays informational calculation messages, while the bottom section lets you enter any explanatory notes that you wish to be associated with the worksheet. Input: •


•


•


•

Discharge Coefficient Weir—Coefficient C used in the general weir equation.

•


Output: •


•


•



3-71

Orifice Worksheet Dialog Boxes

3.11

•


•


Orifice Worksheet Dialog Boxes The available orifice worksheets are as follows:

3.11.1

•

“Rectangular Orifice Dialog Box”

•

“Circular Orifice Dialog Box”

•

“Generic Orifice Dialog Box”

Rectangular Orifice Dialog Box The Rectangular Orifice worksheet dialog box comprises an input section on the left and an output, or results, section on the right. Additionally, a Messages tab is included in each worksheet. The top section of this tab displays informational calculation messages, while the bottom section lets you enter any explanatory notes that you wish to be associated with the worksheet. Input: •


•


•

Centroid Elevation—The elevation of the center of the orifice cross section.

•


•

Discharge Coefficient—Orifice coefficient obtained from experimental data, dependent on the shape of the orifice.

•

Opening Width—Horizontal measurement of the orifice opening.

•

Opening Height—Vertical measurement of the orifice opening.

Output: •

3-72

Headwater Height Above Centroid—Height of the water upstream of the orifice measured from the orifice centroid.



3.11.2

•

Tailwater Height Above Centroid—Height of the water downstream of the orifice measured from the orifice centroid (a negative value indicates that the tailwater is below the centroid elevation).

•


•


Circular Orifice Dialog Box The Circular Orifice worksheet dialog box comprises an input section on the left and an output, or results, section on the right. Additionally, a Messages tab is included in each worksheet. The top section of this tab displays informational calculation messages, while the bottom section lets you enter any explanatory notes that you wish to be associated with the worksheet. Input: •


•


•


•


•


•

Diameter—The inside diameter of a circular channel.

Output: •


•


•


•



3-73

Inlet Worksheet Dialog Boxes

3.11.3

Generic Orifice Dialog Box The Generic Orifice worksheet dialog box comprises an input section on the left and an output, or results, section on the right. Additionally, a Messages tab is included in each worksheet. The top section of this tab displays informational calculation messages, while the bottom section lets you enter any explanatory notes that you wish to be associated with the worksheet. Input •


•


•


•


•


•

Opening Area—Area of the orifice opening.

Output

3.12

•


•


•


Inlet Worksheet Dialog Boxes The available inlet worksheets are as follows:

3-74

•

“Grate Inlet in Sag Dialog Box”

•

“Grate Inlet on Grade Dialog Box”

•

“Curb Inlet in Sag Dialog Box”

•

“Curb Inlet on Grade Dialog Box”

•

“Ditch Inlet in Sag Dialog Box”

•

“Ditch Inlet on Grade Dialog Box”

•

“Slotted Drain Inlet in Sag Dialog Box”



3.12.1

•

“Slotted Drain Inlet on Grade Dialog Box”

•

“Combination Inlet in Sag Dialog Box”

•

“Combination Inlet on Grade Dialog Box”

Grate Inlet in Sag Dialog Box The Uniform Flow tab comprises an input section on the left and an output, or results, section on the right. This dialog box comprises the following tabs: •

“Gutter Tab—Grate Inlet in Sag”

•

“Grate Tab—Grate Inlet in Sag”

•

“Output—Grate Inlet in Sag”


Gutter Tab—Grate Inlet in Sag The Gutter tab comprises an input section on the left and an output, or results, section on the right. Input: •


•


•


•


•



3-75


Grate Tab—Grate Inlet in Sag The Grate tab comprises an input section on the left and an output, or results, section on the right. Input: •

Grate Width—Total width of the grate inlet, which includes the bars (measured in the cross-sectional plane of the roadway).

•

Grate Length—Total length of the grate inlet, including bars (measured in the road direction). The default values for the range of Grate Length are 0.5 ft – 4.5 ft. To change these defaults: right click on the Grate Length field, choose Grate Length Properties and change the maximum and minimum value allowed.

•

Local Depression—Depth of a gutter depression a’ existing only at the location of the inlet.

•

Local Depression Width—Horizontal width of the locally depressed gutter. In the case of a continuously depressed gutter, the larger of the local depression width and gutter width is used to calculate the inlet efficiency.

•

Grate Type—The HEC-22 methodology contains 8 different types of grates, which defines their geometry (spacing, shape of the bars, etc.). The grate type affect the inlet efficiency. The types defined by HEC-22 are:

•

–

Curved Vane

–

30° – 45° Tilt Bar

–

45° – 60° Tilt Bar

–

45° – 85° Tilt Bar

–

P-30

–

P-50

–

P-50 x 100

–

Reticuline

Clogging—The clogging factor accounts for the reduction in efficiency of the inlet due to partial clogging by debris, leaves, etc. The valid range is [0%,100%]. 100% corresponds to a completely clogged grate inlet, resulting in no flow interception.

Output—Grate Inlet in Sag •

3-76




3.12.2

•


•

Total Depression—Total of the local depression (Depth of a gutter depression a’ existing only at the location of the inlet) and the gutter depression (the depth a of the gutter measured at the curb face, from the projection of the pavement crossslope at the curb face).

•

Open Grate Area—Clear opening of the grate used when the grate acts as an orifice (at high water depth). This is a function of the grate length (total length of the grate inlet, including bars, measured in the road direction), the grate width (total width of the grate inlet, which includes the bars, measured in the crosssectional plane of the roadway), the opening ratio, which accounts for the bars of the grate reducing the opening area (specific to each grate type), and the clogging factor (accounts for the reduction in efficiency of the inlet due to partial clogging by debris, leaves, etc. The valid range is [0,1]. 1 corresponds to a completely clogged grate inlet, resulting in no flow interception).

•

Active Grate Weir Length—Weir length of the grate used when the grate acts as a weir (at low water depth). This is a function of the grate length (total length of the grate inlet, including bars, measured in the road direction), the grate width (total width of the grate inlet, which includes the bars, measured in the crosssectional plane of the roadway), and the clogging factor (accounts for the reduction in efficiency of the inlet due to partial clogging by debris, leaves, etc. The valid range is [0,1]. 1 corresponds to a completely clogged grate inlet, resulting in no flow interception).

Grate Inlet on Grade Dialog Box This dialog box comprises the following tabs: •

“Gutter Tab—Grate Inlet on Grade”

•

“Grate Tab—Grate Inlet on Grade”

•

“Output—Grate Inlet on Grade”



3-77


Gutter Tab—Grate Inlet on Grade The Gutter tab comprises an input section on the left and an output, or results, section on the right. Input: •


•

Slope—Longitudinal slope in the channel. Also the vertical drop divided by the channel length. In Irregular Sections, the vertical drop is measured from low point to low point.

•


•


•


•


Grate Tab—Grate Inlet on Grade The Grate tab comprises an input section on the left and an output, or results, section on the right. Input:

3-78

•

Efficiency—Ratio of the Intercepted Flow by the inlet over the total gutter flow. The range is [0,1].

•


•


•

Grate Type—The HEC-22 methodology contains 8 different types of grates, which defines their geometry (spacing, shape of the bars, etc.). The grate type affect the inlet efficiency. The types defined by HEC-22 are: –

Curved Vane

–

30° – 45° Tilt Bar

–

45° – 60° Tilt Bar

–

45° – 85 °Tilt Bar



•

–

P-30

–

P-50

–

P-50 x 100

–

Reticuline

Clogging—The clogging factor accounts for the reduction in efficiency of the inlet due to partial clogging by debris, leaves, etc. The valid range is [0%, 100%]. 100% corresponds to a completely clogged grate inlet, resulting in no flow interception.

Output—Grate Inlet on Grade •

Intercepted Flow—Portion of the flow in the gutter that is captured by the inlet (the remaining portion of the flow that is not intercepted is called bypass flow). Note that the amount of flow intercepted by an inlet in sag is assumed to be 100%.

•

Bypass Flow—Portion of the flow that is not captured by the inlet. The bypass flow is generally captured by inlets downstream. Note that the amount of flow bypassed from an inlet in sag is assumed to be 0.

•


•


•


•


•


•


•

Splash Over Velocity—Gutter velocity where splash-over first occurs. The splash-over velocity is a function of the Grate Type and the Grate Length.

•

Frontal Flow Factor—Ratio of frontal flow intercepted by the grate inlet to total frontal flow.

•

Side Flow Factor—Ratio of side flow intercepted by the grate inlet to total side flow.


3-79

Inlet Worksheet Dialog Boxes •

Grate Flow Ratio—Ratio of frontal flow (portion of flow Qw that is in the gutter within the width of the grate) to total flow.

•

Active Grate Length—Length of the side of the grate that is parallel to the curb (grate length) reduced by the clogging factor. La = Lg (1-f) Where

3.12.3

(3.1) La

= Active grate length (m, ft)

Lg

= Length of the grate (m, ft)

f

= Clogging factor (unitless, f = 1.0 means that the grate is completely clogged

Curb Inlet in Sag Dialog Box This dialog box comprises the following tabs: •

“Gutter Tab—Curb Inlet in Sag”

•

“Curb Tab—Curb Inlet in Sag”

•

“Output—Curb Inlet in Sag”


Gutter Tab—Curb Inlet in Sag The Gutter tab comprises an input section on the left and an output, or results, section on the right. Input:

3-80

•


•


•





•


Curb Tab—Curb Inlet in Sag The Curb tab comprises an input section on the left and an output, or results, section on the right. Input: •

Curb Opening Length—Length of the opening of the curb inlet (measured in the direction of the street).

•


•

Curb Throat Type—3 types of curb inlets are defined: –

Horizontal throat (most common curb inlet)

–

Vertical throat

–

Inclined throat

•


•


•

Throat Incline Angle—Angle of the curb opening throat (measured from the vertical).

Output—Curb Inlet in Sag •


•


•



3-81


3.12.4

Curb Inlet on Grade Dialog Box The curb inlet on grade worksheet dialog box comprises the following tabs: •

“Gutter Tab—Curb Inlet on Grade”

•

“Curb Tab—Curb Inlet on Grade”

•

“Output—Curb Inlet on Grade”


Gutter Tab—Curb Inlet on Grade The Gutter tab comprises an input section on the left and an output, or results, section on the right. Input: •


•

Slope—Longitudinal slope in the channel. Also the vertical drop divided by the channel length. In Irregular Sections, the vertical drop is measured from low point to low point.

•


•


•


•

Roughness Coefficient—Roughness coefficient used in Manning's Formula.

Curb Tab—Curb Inlet on Grade The Curb tab comprises an input section on the left and an output, or results, section on the right. Input:

3-82

•


•





•


Output—Curb Inlet on Grade

3.12.5

•


•


•


•


•


•


•


•


•

Equivalent Cross Slope—An imaginary straight cross-slope having a conveyance capacity equal to that of the given compound cross-slope.

•

Length Factor—Ratio of curb opening length (length of the opening of the curb inlet, measured in the direction of the street) over total interception length (length, LT of the curb opening that would be required to intercept 100% of the flow).

•

Total Interception Length—Length (LT) of the curb opening that would be required to intercept 100% of the flow.

Ditch Inlet in Sag Dialog Box The ditch inlet in sag worksheet dialog box comprises the following tabs: •

“Ditch Tab—Ditch Inlet in Sag”


3-83


“Grate Tab—Ditch Inlet in Sag”

•

“Output—Ditch Inlet in Sag”


Ditch Tab—Ditch Inlet in Sag The Ditch tab comprises an input section on the left and an output, or results, section on the right. Input: •


•


•


•


•

Bottom Width—For a regular channel, width of the bottom of a channel cross section.

Grate Tab—Ditch Inlet in Sag The Grate tab comprises an input section on the left and an output, or results, section on the right. Input:

3-84

•


•


•


•


•




•

–

Curved Vane

–

30° – 45° Tilt Bar

–

45° – 60° Tilt Bar

–

45° – 85° Tilt Bar

–

P-30

–

P-50

–

P-50 x 100

–

Reticuline


Output—Ditch Inlet in Sag •


•


•


•


•

Active Grate Weir Length—Weir length of the grate used when the grate acts as a weir (at low water depth). This is a function of the grate length (total length of the grate inlet, including bars, measured in the road direction), the grate width (total width of the grate inlet, which includes the bars, measured in the crosssectional plane of the roadway), and the clogging factor (accounts for the reduction in efficiency of the inlet due to partial clogging by debris, leaves, etc. The valid range is [0,1]. 1 corresponds to a completely clogged grate inlet, resulting in no flow interception).


3-85


3.12.6

Ditch Inlet on Grade Dialog Box The ditch inlet on grade worksheet dialog box comprises the following tabs: •

“Ditch Tab—Ditch Inlet on Grade”

•

“Grate Tab—Ditch Inlet on Grade”

•

“Output—Ditch Inlet on Grade”


Ditch Tab—Ditch Inlet on Grade The Ditch tab comprises an input section on the left and an output, or results, section on the right. Input: •


•


•


•


•

Bottom Width—For a regular channel, width of the bottom of a channel cross section.

•


Grate Tab—Ditch Inlet on Grade The Grate tab comprises an input section on the left and an output, or results, section on the right. Input:

3-86

•


•


•




•


Curved Vane

–

30° – 45° Tilt Bar

–

45° – 60° Tilt Bar

–

45° – 85° Tilt Bar

–

P-30

–

P-50

–

P-50 x 100

–

Reticuline


Output—Ditch Inlet on Grade •


•


•


•


•


•


•


•


•



3-87



•


(3.2) La


Lg


f


•


•


•


•



–


–

Critical if F = 1 where F is the Froude Number.

3.12.7

•


•


Slotted Drain Inlet in Sag Dialog Box The slotted drain inlet in sag worksheet dialog box comprises the following tabs:

3-88

•

“Gutter Tab—Slotted Drain Inlet in Sag”

•

“Slot Tab—Slotted Drain Inlet in Sag”

•

“Output—Slotted Drain Inlet in Sag”


Bentley FlowMaster Environment Additionally, a Messages tab is included in each worksheet. The top section of this tab displays informational calculation messages, while the bottom section lets you enter any explanatory notes that you wish to be associated with the worksheet.

Gutter Tab—Slotted Drain Inlet in Sag The Gutter tab comprises an input section on the left and an output, or results, section on the right. Input: •


•


•


•


•


Slot Tab—Slotted Drain Inlet in Sag The Slot tab comprises an input section on the left and an output, or results, section on the right. Input: •

Slot Width—Width (W) of the slot length opening.

•

Slot Length—Length of the slot inlet opening.

•


•


Output—Slotted Drain Inlet in Sag •



3-89


3.12.8

•


•


•

Open Slot Area—Area of the slot opening used in the case of orifice flow.

Slotted Drain Inlet on Grade Dialog Box The slotted drain inlet on grade worksheet dialog box comprises the following tabs: •

“Gutter Tab—Slotted Drain Inlet on Grade”

•

“Slot Tab—Slotted Drain Inlet on Grade”

•

“Output—Slotted Drain Inlet on Grade”


Gutter Tab—Slotted Drain Inlet on Grade The Gutter tab comprises an input section on the left and an output, or results, section on the right. Input:

3-90

•


•


•


•


•


•




Slot Tab—Slotted Drain Inlet on Grade The Slot tab comprises an input section on the left and an output, or results, section on the right. Input: •


•

Slot Length—Length of the slot inlet opening.

•


•


Output—Slotted Drain Inlet on Grade •


•


•


•


•


•


•


•


•



3-91


3.12.9

•


•


Combination Inlet in Sag Dialog Box The combination inlet in sag worksheet dialog box comprises the following tabs: •

“Gutter Tab—Combination Inlet in Sag”

•

“Inlet Tab—Combination Inlet in Sag”

•

“Grate Tab—Combination Inlet in Sag”

•

“Curb Tab—Combination Inlet in Sag”

•

“Output—Combination Inlet in Sag”


Gutter Tab—Combination Inlet in Sag The Gutter tab comprises an input section on the left and an output, or results, section on the right. Input:

3-92

•


•


•


•


•




Inlet Tab—Combination Inlet in Sag The Inlet tab comprises an input section on the left and an output, or results, section on the right. Input: •


•


Grate Tab—Combination Inlet in Sag The Grate tab comprises an input section on the left and an output, or results, section on the right. Input: •


•


•


•

–

Curved Vane

–

30° – 45° Tilt Bar

–

45° – 60° Tilt Bar

–

45° – 85° Tilt Bar

–

P-30

–

P-50

–

P-50 x 100

–

Reticuline



3-93


Curb Tab—Combination Inlet in Sag The Curb tab comprises an input section on the left and an output, or results, section on the right. Input: •


•


•

Curb Throat Type—3 types of curb inlets are defined:

•

–

Horizontal throat (most common curb inlet)

–

Vertical throat

–

Inclined throat

Throat Incline Angle—Angle of the curb opening throat (measured from the vertical).

Output—Combination Inlet in Sag

3-94

•


•


•


•


•

Active Grate Weir Length—Weir length of the grate used when the grate acts as a weir (at low water depth). This is a function of the grate length (total length of the grate inlet, including bars, measured in the road direction), the grate width (total width of the grate inlet, which includes the bars, measured in the cross-


Bentley FlowMaster Environment sectional plane of the roadway), and the clogging factor (accounts for the reduction in efficiency of the inlet due to partial clogging by debris, leaves, etc. The valid range is [0,1]. 1 corresponds to a completely clogged grate inlet, resulting in no flow interception).

3.12.10

Combination Inlet on Grade Dialog Box The combination inlet on grade worksheet dialog box comprises the following tabs: •

“Gutter Tab—Combination Inlet on Grade”

•

“Inlet Tab—Combination Inlet on Grade”

•

“Grate Tab—Combination Inlet on Grade”

•

“Curb Tab—Combination Inlet on Grade”

•

“Output—Combination Inlet on Grade”


Gutter Tab—Combination Inlet on Grade The Gutter tab comprises an input section on the left and an output, or results, section on the right. Input: •


•


•


•


•


•



3-95


Inlet Tab—Combination Inlet on Grade The Inlet tab comprises an input section on the left and an output, or results, section on the right. Input: •


•


•


Grate Tab—Combination Inlet on Grade The Grate tab comprises an input section on the left and an output, or results, section on the right. Input:

3-96

•


•


•


Curved Vane

–

30° – 45° Tilt Bar

–

45° – 60° Tilt Bar

–

45° – 85° Tilt Bar

–

P-30

–

P-50



•

–

P-50 x 100

–

Reticuline


Curb Tab—Combination Inlet on Grade The Curb tab comprises an input section on the left and an output, or results, section on the right. Input: •


Output—Combination Inlet on Grade •


•


•


•


•


•


•


•


•



3-97

Combination Inlet Options Dialog Box •


•


•


•


•


3.13

(3.3) La


Lg


f


•


•


Combination Inlet Options Dialog Box This dialog box lets you modify certain calculation options. The controls available to do this are as follows:

3-98

•

Calculation Option—This menu lets you use the curb inlet, grate inlet, or both during the calculations.

•

Grate Flow Option—This menu lets you exclude front flow, side flow, or neither duing the calculations.



3.14

Rating Table Setup Dialog Box This dialog box lets you define the parameters of a rating table for the associated worksheet. The dialog includes a tabular grid and the following control buttons: •

Insert—Creates a new row in the tabular grid.

•

Delete—Deletes the selected row in the tabular grid.

The tabular grid contains the following columns: •

3.14.1

Attribute—This drop-down list lets you choose the attribute to which the rating table will be applied. The options include: –

Roughness Coefficient

–

Channel Slope

–

Normal Depth

–

Bottom Width

–

Right/Left-Side Slope

•

Minimum—The lower limit of the user-specified range.

•

Maximum—The upper limit of the user-specified range.

•

Increment—This value determines how the range determined by the Minimum and Maximum values is broken down.

Rating Table Dialog Box The Rating Table dialog box displays the result of the rating table defined in the Rating Table Setup dialog box. The following buttons are available: •

Define Rating Table—This button opens the Rating Table Setup dialog box, letting you redefine the table parameters.

•

Print Preview—This button opens the print preview dialog box, displaying the current rating table as it will be printed.


3-99

Rating Curve Setup Dialog Box

3.15

Rating Curve Setup Dialog Box This dialog box lets you plot one or more curves for each worksheet. You can plot a single curve or a family of curves. The following controls are available:

3.15.1

•

Varying (check box)—When this box is checked, the Varying fields become active, allowing another attribute (for a total of three) to be plotted.

•

Plot (drop-down list)—The attribute along the y (vertical) axis.

•

Vs (drop-down list)—The attribute along the x (horizontal) axis.

•

Minimum—The lower limit of the user-specified range for the associated attribute.

•

Maximum—The upper limit of the user-specified range for the associated attribute.

•


•

Varying—When the Family of Curves check box is checked, this menu lets you choose a third attribute to plot.

•

Minimum—The lower limit of the user-specified range for the associated attribute.

•

Maximum—The upper limit of the user-specified range for the associated attribute.

•


Rating Curve Dialog Box The rating curve dialog box displays the result of the rating table defined in the Rating Curve Setup dialog box. The following buttons are available:

3-100

•

Define Rating Curve—This button opens the Rating Curve Setup dialog box, letting you redefine the table parameters.

•

Print Preview—This button opens the print preview dialog box, displaying the current rating table as it will be printed.

•

Chart Options—This button opens the TeeChart Editor dialog box, letting you modify the graph display options.



3.16

Cross Section Report Setup Dialog Box This dialog box lets you modify the display settings of the cross section report. The following controls are available:

3.17

•

Report Title—Enter the title for your report; the title displays at the top of the printed report.

•

Aspect Ratio—This control is inactive unless the Manual Scale box is checked.value determines the scale of the cross section diagram. It increases or decreases the size of the diagram relative to the default value of 1. This option is not available for irregular cross sections.

•

Manual Scale—Clicking this check box activates the Aspect Ratio control, letting you increase or decrease the size of the cross section diagram. This option is not available for irregular cross sections.

Cross Section Dialog Box This dialog box displays a cross section of the current element using the settings defined in the Cross Section Report Setup dialog box. The dialog box contains the following buttons: •

Print Preview—This command opens the Print Preview dialog box, displaying the cross section as it will appear when it is printed.

•

Options—This command opens the Cross Section Report Setup dialog box, letting you change the report settings.

Irregular cross-sections are displayed on a grid.

3.18

Irregular Section Editor Dialog Box This dialog box lets you define a cross section for the associated irregular section. The dialog box comprises the following sections: •

Section Geometry—This section of the dialog box lets you specify the points that allow you to define the channel shape. A point is defined by entering a station value along with the elevation at that station point. The following controls are available in this section of the dialog box: –

Insert (button)—This button creates a new point in the section table.

–

Delete (button)—This button deletes the selected point from the section table.


3-101

Weighted Roughness Method Dialog Box

•

•

3.19

–

Station (column)—This column lets you enter the station for which the associated elevation applies in the cross section.

–

Elevation (column)—This column lets you define the elevation for the associated station to define a point in the cross section.

Segment Roughness—This section of the dialog box lets you define the roughness along specific segments of the cross section. Each segment can be assigned a different roughness value. –

Insert (button)—This button creates a new point in the section table.

–

Delete (button)—This button deletes the selected point from the section table.

–

Start Station—This column contains a menu containing all of the available station points. By defining this point and the end point, a segment can be defined, and a roughness coefficient can then be applied to this segment.

–

End Station—This column contains a menu containing all of the available station points. By defining this point and the start point, a segment can be defined, and a roughness coefficient can then be applied to this segment.

–

Roughness Coefficient—The roughness value (Manning’s) that is to be associated with the segment defined by the start and end station values.

Section Plot—This section of the dialog box displays a continuously updated diagram of the cross section that is defined in the Sections table. Segments appear red when no roughness has been defined in the Segment section, and appear green when roughness values have been defined.

Weighted Roughness Method Dialog Box The Weighted Roughness Method dialog box lets you define the roughness method that will be used in the calculations. Separate methods can be chosen for open and closed channels. The currently specified method is displayed in the Current Roughness Method field. The following methods are available:

3.19.1

Open and Closed Channel Weighting Methods Bentley FlowMaster uses the following weighting methods: •

3-102

Pavlovskii’s Method—The Pavlovskii method may be used for open channel as well as closed top irregular channels.



N

(PN nN2 )

1

n=

P

Where

2 2 2 Pn 1 1 + P2 n2 + .... + PN nN P

=

n

=

Roughness coefficient

P

=

Weighted perimeter

(3.4)

Subscripts represents subdivisions of one given section •

Horton’s Method—The Horton composite roughness equation is normally used for solving closed top irregular channels such as custom arches or cunnette conduit sections. This equation is also applied in certain specific situations to open channels where steep banks or wide flat floodplains are encountered. N

2

PN n1N.5

(

3

2

)

1.5 1.5 1.5 3 Pn ( 1 1 + P2 n2 + .... + PN nN ) =

1

n=

P Ł

Where

P

2

3

ł

(3.5)

n

=


P

=

Wetted perimeter Subscripts represents subdivisions of one given section

•

Colebatch Method—The Colebatch equation is normally used for open, irregular channels such as natural floodplains. N

2

AN n1N.5

(

)

1

n=

A Ł


3

2

A1n11.5 + A2 n12.5 + .... + AN n1N.5 ) 3 ( = A

ł

2

3

(3.6)

3-103

Weighted Roughness Method Dialog Box

Where

n

=


A

=

Flow area Subscripts represents subdivisions of one given section

•

Cox Method—The Cox equation is normally used for open, irregular channels such as natural floodplains. N

(AN nN ) n=

1

=

A

Where

A1n1 + A2 n2 + .... + AN nN A

n

=


A

=

Flow area

(3.7)

Subscripts represents subdivisions of one given section •

Lotter Method—The Lotter equation is normally used for open, irregular channels such as natural floodplains.

n=

PR N 1

3-104

5

PR

3 5

=

PN RN 3 Ł nN ł

5

5

5

3 5

P1R1 3 P2 R2 3 P R 3 + + .....+ N N n1 n2 nN

(3.8)



Where

n

=


P

=

Wetted perimeter

R

=

Hydraulic radius Subscripts represents subdivisions of one given section

•

3.19.2

Improved Lotter Method—This method uses a combination of the Horton and Lotter equations. Because both methods are based on Manning’s conveyance equations, it is recommended that you use Manning’s friction method for irregular channels. For more information, see “Note to HEC-2, WSP-2, and WSPRO Users” on page 3-105.

Note to HEC-2, WSP-2, and WSPRO Users Improved Lotter Method uses a weighted roughness method for solving uniform flow equations unlike most standard step backwater programs (HEC-2, WSP-2, and WSPRO), which use a segmented conveyance method. Improved Lotter weighted roughness method is more general and, unlike the step backwater programs, can be used for both open channel sections and closed sections. Improved Lotter Method will produce results similar to the segmented conveyance method (HEC-2, WSP-2, WSPRO) except for the following two cases: Sections containing steep vertical segments or flat shallow submerged overbanks intersected by water surface. The segmented conveyance method (HEC-2, WSP-2, and WSPRO) tends to underestimate effective roughness, and in many instances the effective weighted roughness will be actually lower than any of the input segment roughnesses. Bentley FlowMaster's weighted roughness method avoids underestimating effective roughness by combining adjacent segments using Horton's equation in a manner similar to the method applied for subdivided main channels with banks steeper than 5H:1V as documented in Section 2.3 of the HEC-2 User's Manual (September, 1990). Unlike HEC-2, Improved Lotter Method does not confine this correction to the main channel, but will make this adjustment at any location in the section. Improved Lotter Method also dynamically adjusts its flatness and steepness checks ensuring that computed roughness values will always be higher than the minimum input value encountered over the wetter flow area. For these situations, Improved Lotter Method yields a higher effective weighted roughness for the total section than the segmented conveyance method.


3-105

Options Dialog Box

3.20

Options Dialog Box The Options dialog box contains two tabs:

3.20.1

•

“Options Dialog Box - FlexUnits Tab”

•

“Options Dialog Box - ProjectWise Tab”

Options Dialog Box - FlexUnits Tab The FlexUnits tab lets you modify the unit settings for the current project. Click Tools > Options to open the FlexUnits tab in the Options dialog box. The FlexUnits tab contains the following controls: •

Save As—This button lets you setup your own set of unit defaults, so you can load them in later. Save As saves the defaults as an XML file that you can edit in an XML editor or text editor, such as Notepad.

•

Load—This button lets you open your own set of custom unit defaults. These defaults are saved as an XML file, which you can create using Save As.

•

Reset Defaults SI—This button sets the unit system used by the current project to SI.

•

Reset Defaults US—This button sets the unit system used by the current project to U.S. customary.

•

Default Unit System for New Project—Sets the default unit system used by future new projects, not for the current project.

The table comprises the following columns:

3-106

•

Formatter—Parameter measured by the unit.

•

Unit—Type of measurement displayed. To change the unit of an attribute type, click the choice list and click the unit you want. This option also lets you use both US Customary and SI units in the same worksheet.

•

Display Precision—Rounding of numbers and number of digits displayed after the decimal point. Enter a negative number for rounding to the nearest power of 10: (-1) rounds to 10, (-2) rounds to 100, (-3) rounds to 1000, and so on. Enter a number from 0 to 15 to indicate the number of digits after the decimal point.

•

Format—Select the format for your numbering. For more information, see “Set Field Options Dialog Box” on page 3-114.

•

Default Unit System for New Project—Sets the default unit system used by future new projects, not for the current project.



3.20.2

Options Dialog Box - ProjectWise Tab Note:

These settings affect ProjectWise users only.

The ProjectWise tab contains options for using FlowMaster with ProjectWise. This tab contains the following controls: •

Default Datasource—Displays the current ProjectWise datasource. If you have not yet logged into a datasource, this field will display . To change the datasource, click the Ellipses (...) button to open the Change Datasource dialog box. If you click Cancel after you have changed the default datasource, the new default datasource is retained.

•

Update server on Save—When this is checked, any time you save your FlowMaster project locally using the File > Save menu command, the files on your ProjectWise server will also be updated and all changes to the files will immediately become visible to other ProjectWise users. This option is turned off by default. Note:

This option, when turned on, can significantly affect performance, especially for large, complex projects.

For more information about using FlowMaster with ProjectWise, see “Considerations for ProjectWise Users” on page 3-115

3.21

Project Properties Dialog Box This dialog box lets you view and modify project information, including the date, engineer, filename, and any notes associated with the project. Click Project > Project Properties to open the Project Properties dialog box. •

Categorized (button)—Click this to display the categories in the Project Properties dialog box (Misc. is the only category).

•

Alphabetic (button)—Click this to display the Project Properties alphabetically without categories.

•

Project Engineer—This field lets you enter the project engineer’s name.

•

Project Company—This field lets you enter your company’s name, which will appear on the bottom of all reports associated with the current project. This is an optional field.

•

Company Logo—This field lets you select a logo (.bmp file) to display at the bottom of all reports associated with the current project. Click in this field to display an Ellipses button, which lets you browse your computer for the appropriate logo. This is an optional field.


3-107

GVF Profile Dialog Box

3.22

•

Project Notes—This field lets you enter any notes that you wish to be associated with the project.

•

Project Date—This field is automatically populated with the date and time that the project was created. The data in this field can be modified by clicking the arrow button on the right side of the field and selecting a date on the calendar that appears.

•

Project Filename—This field is automatically populated with the file name and location of the project file. Bentley FlowMaster creates data files with the format: yourfilename.fm8 and yourfilename.fm8.mdb. By default, projects are saved to your \My Documents directory, but you can save them to any directory that you specify.

GVF Profile Dialog Box The GVF Profile dialog box displays a diagram of the calculated gradually-varied profile. A Print Preview button is available, letting you see what the profile will look like when it is printed. To view a GVF profile: 1. Create a new worksheet. 2. Enter the data. 3. Click Solve. 4. Click the GVF Profile button.

3.23

GVF Profile Table Dialog Box The GVF Profile Table dialog box displays the results of the gradually-varied flow calculations in a tabular format. To view a GVF profile table: 1. Create a new worksheet. 2. Enter the data. 3. Click Solve. 4. Click the GVF Profile Table button. The columns in the table are as follows:

3-108

•

Distance

•

Depth



Invert Elevation

•

Flow Area

•

Wetted Perimeter

•

Velocity

•

Specific Energy

A Print Preview button is available, letting you see what the report will look like when it is printed.

3.24

Tabular Reports The tabular report dialog box displays all available input data and results for each of the worksheet types. The attributes that are reported will vary according to the type of element being calculated. You can customize tabular reports in the following ways: •

Change the report title

•

Add and remove columns

•

Move columns

•

Resize columns

•

Change column headings

•

Copy data to the Windows clipboard

•

Sort the contents of a column

•

Filter the contents of a table •

3.24.1

Tabular Report Dialog Box The tabular report dialog box displays all available input data and results for each of the worksheet types. The attributes that are reported will vary according to the type of element being calculated. The following controls are available in the Tabular Reports dialog box: •

Copy—This button lets you copy the contents of the selected table cell, rows, and/ or columns for the purpose of pasting into a text editing program such as Notepad.


3-109

Tabular Reports •

Report—This button displays the Print Preview dialog box, which lets you see what the report will look like when it is printed. For more information, see “Print Preview Dialog Box” on page 3-113. When you click the Report button, you are prompted to change the title of the report, if you wish.

•

Edit—Opens the Tabular Report Setup dialog box, allowing you to make changes to the format of the currently selected table. For more information, see “Tabular Report Setup Dialog Box” on page 3-111.

Right-clicking on a column heading in the Tabular Reports displays a shortcut menu containing the following commands: •

Units and Formatting—Displays the Set Field Options dialog box, letting you change the units, display precision, and format of the data displayed in the currently selected column. For more information, see “Set Field Options Dialog Box” on page 3-114.

•

Edit Column Label—Lets you change the text of a column label. Right-click the column whose label you want to change, then select this command and type the new name for the label ion the Edit Column Label dialog box. Click OK to save those changes and close the dialog box or Cancel to exit without making any changes.

•

Sort—Displays a submenu containing the following sorting commands:

•

–

Sort Ascending—Sorts the contents of the currently-selected column alphabetically from A to Z, from top to bottom. Sorts numerically from negative to positive, from top to bottom. Sorts selected check boxes to the top and cleared ones to the bottom.

–

Sort Descending—Sorts the contents of the currently-selected column alphabetically from Z to A, from top to bottom. Sorts numerically from positive to negative, from top to bottom. Sorts cleared check boxes to the top and selected ones to the bottom.

–

Custom—Displays the Custom Sort dialog box, which lets you select one or more attribute by which to sort the contents of the selected column. For more information, see “Custom Sort Dialog Box” on page 3-112.

Filter—Displays a submenu containing the following commands: –

3-110

Quick Filter—Displays the Filter dialog box, which lets you filter the contents of the tabular report by the currently-selected column. For example, if you wanted to view data only for trapezoidal channels with a normal depth greater than or equal to 5 feet, you would create a quick filter by right-clicking the Normal Depth column, then selecting Filter > Quick Filter to display the Filter dialog box. You would then set the operator to >= and the value to 5 and click OK; only the data for channels that meet your filter criteria will be displayed.



3.24.2

–

Custom—Displays the Filter dialog box, which lets you set up a custom filter based on one or more criteria. For more information, see “Filter Dialog” on page 3-112.

–

Reset—Turns off the active filter, causing all available rows in the table to be displayed.

Tabular Report Setup Dialog Box The Tabular Report Setup dialog box allows you to customize any table through the following options: •

Available Columns—Contains all the attributes that are available for your table design. The Available Columns list is located on the left side of the dialog box. This list contains all of the attributes that are available for the type of table you are creating. The attributes displayed in yellow represent non-editable attributes, while those displayed in white represent editable attributes.

•

Selected Columns—Contains attributes that appear in your custom designed tabular report. When you open the table, the selected attributes appear as columns in the table in the same order that they appear in the list. You can drag and drop or use the up and down buttons to change the order of the attributes in the table. The Selected Columns list is located on the right-hand side of the Tabular Report Setup dialog box. To add columns to the Selected Columns list, select one or more attributes in the Available Columns list, then click the Add button [>] or drag and drop the highlighted attributes to the Selected Columns list.

•

Column Manipulation Buttons—Lets you select or clear columns to be used in the table, as well as to arrange the order in which the columns appear. The Add and Remove buttons are located in the center of the dialog box. –

[ > ]—Adds the selected items from the Available Columns list to the Selected Columns list.

–

[ >> ]—Adds all of the items in the Available Columns list to the Selected Columns list.

–

[ < ]—Removes the selected items from the Selected Columns list.

–

[ << ]—Removes all items from the Selected Columns list.

Note:

You can select multiple attributes in the Available Columns list by holding down the Shift key or the Control key while clicking with the mouse. Holding down the Shift key provides group selection behavior. Holding down the Control key provides single element selection behavior.


3-111

Tabular Reports To rearrange the order of the attributes in the Selected Columns list, highlight the item to be moved, then move it up or down in the list by dragging or clicking the up or down button located below the Selected Columns list.

3.24.3

Custom Sort Dialog Box When you perform a Custom Sort in a tabular report, the Custom Sort dialog box opens, letting you select one or more attributes by which to sort the contents of the selected column. The Custom Sort dialog box contains a table in which you define custom sort keys, and the following controls: •

Insert—Inserts a new row into the table. Each row in the table represents a separate sort key.

•

Delete—Deletes the current row (and sort key) from the table.

Each sort key contains two parts:

3.24.4

•

Attribute—The attribute to sort. You can select any field in the tabular report from a drop-down list.

•

Sort Order—The order in which to sort the selected attribute’s values. Select Ascending or Descending.

Filter Dialog When you perform a Quick Filter or a Custom Filter in a tabular report, the Filter Editor dialog opens, letting you specify one or more filter criteria. The Filter dialog box contains a table, each row of which represents a filter criterion, and the following controls: •

Insert—Inserts a new row into the table. Each row in the table represents a separate filter criterion.

•

Delete—Deletes the current row (and filter criterion) from the table.

Each filter criterion contains three parts:

3-112

•

Attribute—The attribute to filter.

•

Operator—The operator to use when comparing the filter value against the data in the specific column (operators include: =, >, >=, <, <=, <>).

•

Value—The comparison value.


Bentley FlowMaster Environment Any number of criterion elements can be added to a filter. Multiple filter criteria are implicitly joined with a logical AND statement. When multiple filter criterian are defined, only rows that meet all of the specified criteria will be displayed. A filter will remain active for the associated table until the filter is reset.

3.25

Print Preview Dialog Box The Print Preview dialog box lets you see the current view of the chart as it will be printed, and to define the print settings. The following controls are available in this dialog box: •

Table of Contents (button)—Displays the table of contents for the current pump chart.

•

Print (button)—Prints the current chart as it appears in the preview pane.

•

Copy (button)—Copies the text from the Print Preview dialog box to the Windows clipboard. You can paste (Ctrl+V) the data into other software, such as a word-processing application or Notepad.

•

Find (button)—Lets you search for words and phrases in the chart displayed in the preview pane.

•

Single Page View (button)—Displays a single page in the preview pane.

•

Multiple Page View (button)—Lets you display multiple pages simultaneously in the preview pane.

•

Zoom Out (button)—Magnifies the current view in the preview pane; you can only use this with single-page view.

•

Zoom In (button)—Reduces in the current view in the preview pane; you can only use this with single-page view.

•

Zoom (drop-down list)—Lets you select the magnification level of the current view in the preview pane.

•

Previous Page (button)—Returns the report to the previous page.

•

Next Page (button)—Advances the report to the next page.

•

Current Page Number—Displays the current page number and the total pages in the current preview.

•

Backward/Forward (buttons)—Let you navigate to and from pages you have already viewed.


3-113

Set Field Options Dialog Box

3.26

Set Field Options Dialog Box The Set Field Options dialog box lets you view and edit the unit, display precision, and format of the data displayed in the corresponding attribute field. To open this dialog box, right-click any unit in any Bentley FlowMaster dialog box and select Units and Formatting. (For more information, see “Options Dialog Box” on page 3106.) The Set Field Options dialog box comprises the following components:

3-114

•

Value (field)—This non-editable field displays a preview of the appearance of the current unit when the current field options are applied.

•

Units (drop-down list)—This menu lets you select the units used by the current field.

•

Display Precision (field)—This field lets you define the display precision for the current field. The display precision setting can be used to control the number of digits displayed after the decimal point, or the rounding of numbers. Enter a negative number to specify rounding to the nearest power of 10. (-1) rounds to the nearest 10, (-2) rounds to the nearest 100, and so on. For example, if the display precision is set to (-3), a value of 1234567.89 displays as 1235000.

•

Format (drop-down list)—This menu lets you select the display format used by the current field. Choices include: –

Scientific—When using scientific format, the entered value is converted to a string of the form “-d.ddd...E+ddd” or “-d.ddd...e+ddd”, where each 'd' indicates a digit (0 – 9). The string starts with a minus sign if the number is negative.

–

Fixed Point—Fixed point format abides by the display precision setting, and will automatically enter zeros after the decimal place to do so. With a display precision of 3, an entered value of 3.5 will appear as 3.500.

–

General—The general format truncates any zeros after the decimal point, regardless of the display precision value. With a display precision of 3, the value that would appear as 5.200 in Fixed Point format will appear as 5.2 when using General format. The number will also be rounded. So, an entered value of 5.35 will appear as 5.4, regardless of the display precision.

–

Number—When using the number format, the entered value is converted to a string of the form “-d,ddd,ddd.ddd...”, where each 'd' indicates a digit (0 – 9). The string starts with a minus sign if the number is negative. Thousand separators are inserted between each group of three digits to the left of the decimal point.



3.27

Considerations for ProjectWise Users Bentley ProjectWise provides managed access to FlowMaster content within a workgroup, across a distributed organization, or among collaborating professionals. When ProjectWise is integrated with FlowMaster, project files can be accessed quickly, checked out for use, and checked back in directly from within FlowMaster. If ProjectWise is installed on your system, FlowMaster automatically installs all the components necessary for you to use ProjectWise to store and share your FlowMaster projects. To learn more about ProjectWise, refer to the ProjectWise online help. To learn more about using ProjectWise with FlowMaster, see the following topics:

3.27.1

•

“General Guidelines for using ProjectWise with FlowMaster” on page 3-115

•

“Performing ProjectWise Operations from within FlowMaster” on page 3-116

General Guidelines for using ProjectWise with FlowMaster Follow these guidelines when using FlowMaster with ProjectWise: •

Use the File > ProjectWise commands to perform ProjectWise file operations, such as Save, Open, and Change Datasource.

•

The first time you choose one of the File > ProjectWise menu commands in your current FlowMaster session, you are prompted to log into a ProjectWise datasource. The datasource you log into remains the current datasource until you change it using the File > ProjectWise > Change Datasource command.

•

Use FlowMaster’s File > New command to create a new project. The project is not stored in ProjectWise until you select File > ProjectWise > Save As.

•

Use FlowMaster’s File > Open command to open a local copy of the current project.

•

Use FlowMaster’s File > Save command to save a copy of the current project to your local computer.

•

When you Close a project already stored in ProjectWise using File > Close, you are prompted to select one of the following options: –

Check In—Updates the project in ProjectWise with your latest changes and unlocks the project so other ProjectWise users can edit it.

–

Unlock—Unlocks the project so other ProjectWise users can edit it but does not update the project in ProjectWise. Note that this will abandon any changes you have made since the last server update.


3-115

Considerations for ProjectWise Users –

Leave Out—Leaves the project checked out so others cannot edit it and retains any changes you have made since the last server update to the files on your local computer. Select this option if you want to exit Bentley FlowMaster but continue working on the project later.

•

In the FlowMaster Options dialog box, there is a ProjectWise tab with the Update server on Save check box. This option, when turned on, can significantly affect performance, especially for large, complex projects. When this is checked, any time you save your FlowMaster project locally using the File > Save menu command, the files on your ProjectWise server will also be updated and all changes to the files will immediately become visible to other ProjectWise users. This option is turned off by default.

•

In this release of FlowMaster, calculation result files are not managed inside ProjectWise. A local copy of reulsts is maintained on your computer, but to ensure accurate results you should recalculate projects when you first open them from ProjectWise.

•

FlowMaster projects associated with ProjectWise appear in the Most Recently Used Files list (at the bottom of the File menu) in the following format: pwname://PointServer:_TestDatasource/Documents/TestFolder/Test1.prj

3.27.2

Performing ProjectWise Operations from within FlowMaster You can quickly tell whether or not the current FlowMaster project is in ProjectWise or not by looking at the title bar and the status bar of the FlowMaster window. If the current project is in ProjectWise, “pwname://” will appear in front of the file name in the title bar, and a ProjectWise icon will appear on the far right side of the status bar, as shown below.

You can perform the following ProjectWise operations from within FlowMaster: To save an open FlowMaster project to ProjectWise: 1. In FlowMaster, select File > ProjectWise > Save As. 2. If you haven’t already logged into ProjectWise, you are prompted to do so. Select a ProjectWise datasource, type your ProjectWise user name and password, then click Log in.

3-116


Bentley FlowMaster Environment 3. In the ProjectWise Save Document dialog box, enter the following information: a. Click Change next to the Folder field, then select a folder in the current ProjectWise datasource in which to store your project. b. Type the name of your FlowMaster project in the Name field. We recommend that you keep the ProjectWise name the same as or as close to the FlowMaster project name as possible. c. Keep the default entries for the rest of the fields in the dialog box d. Click OK. To open a FlowMaster project from a ProjectWise datasource: 1. Select File > ProjectWise > Open. 2. If you haven’t already logged into ProjectWise, you are prompted to do so. Select a ProjectWise datasource, type your ProjectWise user name and password, then click Log in. 3. In the ProjectWise Select Document dialog box, perform these steps: a. From the Folder drop-down menu, select a folder that contains FlowMaster projects. b. In the Document list box, select a FlowMaster project. c. Keep the default entries for the rest of the fields in the dialog box d. Click Open. To copy an open FlowMaster project from one ProjectWise datasource to another: 1. Select File > ProjectWise > Open to open a project stored in ProjectWise. 2. Select File > ProjectWise > Change Datasource. 3. In the ProjectWise Log in dialog box, select a different ProjectWise datasource, then click Log in. 4. Select File > ProjectWise > Save As. 5. In the ProjectWise Save Document dialog box, change information about the project as required, then click OK. To make a local copy of a FlowMaster project stored in a ProjectWise datasource: 1. Select File > ProjectWise > Open. 2. If you haven’t already logged into ProjectWise, you are prompted to do so. Select a ProjectWise datasource, type your ProjectWise user name and password, then click Log in.


3-117

Considerations for ProjectWise Users 3. Select File > Save As. 4. Save the FlowMaster project to a folder on your local computer. To change the default ProjectWise datasource: 1. Start FlowMaster. 2. Select File > ProjectWise > Change Datasource. 3. In the ProjectWise Log in dialog box, type the name of ProjectWise datasource you want to log into, then click Log in. To use background layer files with ProjectWise:

3-118

•

Using File > ProjectWise > Save As—If there are background files, you are prompted with two options: you can copy the background layer files to the project folder for use by the project, or you can remove the background references and manually reassign them once the project is in ProjectWise to other existing ProjectWise documents.

•

Using File > ProjectWise > Open—This works the same as the normal ProjectWise > Open command, except that background layer files are not locked in ProjectWise for the current user to edit. The files are intended to be shared with other users at the same time.

•

To add a background layer file reference to a project that exists in Project Wise— The ProjectWise Select Document dialog box opens, and you can choose any existing ProjectWise document. You must have previously added these background layer files as described in the first bullet above, or by using the ProjectWise Explorer.

•

When you remove a background layer file reference from a project that exists in ProjectWise, the reference to the file is removed but the file itself is not deleted from ProjectWise.

•

Using File > Save As—When you use File > Save As on a project that is already in ProjectWise and there are background layer files, you are prompted with two options: you can copy all the files to the local project folder for use by the project, or you can remove the background references and manually reassign them after you have saved the project locally.


Chapter

4

How Do I…

This section provides step-by-step instructions for performing Bentley FlowMaster’s most commonly used functions. These functions include the following: •

“Create A New Project” on page 4-120

•

“Open an Existing Project” on page 4-121

•

“Create a New Worksheet?” on page 4-121

•

“Name a Worksheet” on page 4-122

•

“Edit a Worksheet” on page 4-122

•

“Create a Rating Table” on page 4-123

•

“Plot Rating Curves” on page 4-124

•

“Plot a Cross Section” on page 4-125

•

“Print a Report” on page 4-125

•

“Customize a Tabular Report” on page 4-126

•

“Set Field Options (Unit, Precision, Format)” on page 4-129

•

“Save a Project” on page 4-129

•

“Exit Bentley FlowMaster” on page 4-129


4-119

Create A New Project

4.1

Create A New Project When you first start Bentley FlowMaster, the Welcome dialog box opens, which lets you create a new project. You can also create a new project from Bentley FlowMaster’s Main Window when a project is currently open. Both methods of creating a new project are explained here.

4.1.1

Creating a New Project From the Welcome Dialog Box To create a new project from the Welcome dialog box: 1. If Bentley FlowMaster is not open, start Bentley FlowMaster, then, in the Welcome dialog box, click the Create New Project button. Note:

You can click Help > Welcome Dialog to open the Welcome dialog box if

2. The Main Window opens to a new, untitled project.

4.1.2

–

To name the project, click File > Save As. In the Save As dialog box, enter the filename you want to use; then click Save.

–

To setup the Project Properties, click Project > Properties, then enter your data into the Project Properties dialog box.

–

To set up the units for the project, click Project > FlexUnits, then make any changes.

Creating a New Project from the Main Window You can create a new project from Bentley FlowMaster’s Main Window by using the menus or the toolbar: 1. To create a new project from the Bentley FlowMaster menu, in the Main Window, click File > New > Project (Ctrl+N). Alternatively, to create a new project from the Bentley FlowMaster toolbar, in the Main Window, click the New button’s down arrow and select Project. 2. The Main Window opens to a new, untitled project. –

4-120

To name the project, click File > Save As. In the Save As dialog box, enter the filename you want to use; then click Save.


How Do I… –

To setup the Project Properties, click Project > Properties, then enter your data into the Project Properties dialog box.

–

To set up the units for the project, click Project > FlexUnits, then make any changes.

Note:

4.2

Any project that was already open when you created the New Project is still open. Both the old and new project display in the Project Explorer window.

Open an Existing Project When you first start Bentley FlowMaster, the welcome dialog box opens, which lets you open an existing project. You can also open an existing project from Bentley FlowMaster’s Main Window when another project is currently open. 1. Use one of the following methods to open an existing project: –

In the Welcome dialog box, click the Open Existing Project button.

–

In the Bentley FlowMaster menu, click File > Open (Ctrl+O).

–

In the Bentley FlowMaster toolbar, click the Open button.

2. In the Select Project to Open dialog box, browse to the directory where your project is saved. 3. Click the project to highlight it, then click the Open button.

4.3

Create a New Worksheet? When you first start Bentley FlowMaster, the welcome dialog box opens, which lets you create a new worksheet. You can also create a new worksheet from Bentley FlowMaster’s Main Window when a project is currently open, and from the Project Explorer window. 1. Use one of the following methods to create a new worksheet: –

In the Welcome dialog box, click Create Worksheet.

–

In the Bentley FlowMaster menu, click File > New > Worksheet (Ctrl+W).

–

In the Bentley FlowMaster toolbar, click the New button’s down arrow and select Worksheet.

–

In the Project Explorer, right-click an existing project, then select Add > New Worksheet.


4-121

Name a Worksheet 2. In the Create New Worksheet dialog box: a. In the Categories pane, click the element group from which you want to create your worksheet. b. In the Worksheets pane, click the worksheet you want to use. 3. Click OK.

4.4

Name a Worksheet When you create a new worksheet, it is assigned an automatically generated name that comprises the worksheet type followed by a number (the number is incremental). 1. Use one of the following methods to rename a worksheet: –

In the Project Explorer window, click once on the worksheet label (to the right of the worksheet icon), to highlight it, then click the highlighted label again and the label becomes editable.

–

Right-click on the worksheet whose name you wish to change and select Rename from the shortcut menu.

2. Type the name of the worksheet and press Enter.

4.5

Edit a Worksheet Each worksheet dialog box comprises multiple tabs, and is divided along the center into two sections. The section on the left is for input, and the section on the right is output, or results. To edit a worksheet, open it by double-clicking it in the Project Explorer. Then you can:

4-122

•

Enter input data.

•

Change the variable you are solving for by clicking the Solve For drop-down list and making a selection.

•

Choose the friction method to use in the calculations (available in some worksheet types). Certain input and output variables are enabled and disabled depending on the friction method you choose.

•

Set or edit the roughness coefficient by clicking the Ellipsis (…) button next to the Roughness Coefficient field. Then, choose a predefined roughness coefficient based on the material used.


How Do I…

4.6

•

Right-click any units to set the Units and Formatting options for any field.

•

Move from field to field by clicking on the field with the mouse or pressing Tab or Shift+Tab.

Create a Rating Table A rating table shows how one or more (dependent) attributes change as another (independent) attribute is changed. For example, for a series of depths in a channel, you can show what the flow and velocity are. You might use rating tables to evaluate and show the performance of a design over a range of conditions that it might experience. You can create a rating table for every worksheet. The left side of the rating table corresponds with the input fields on the left side of the worksheet, while the right side of the rating table ranges of values for the fields on the left half of the rating table. To create a rating table: 1. Open the worksheet on which you want to base the rating table, and enter your data into it. 2. Click Solve to calculate the worksheet. 3. Click the worksheet dialog box for which you want to create the rating table. 4. Click Analysis > Rating Table or click the Rating Table button. The Rating Table Setup dialog box opens. 5. In the Rating Table Setup dialog box, choose the attributes you want solved—you can select multiple attributes. 6. Enter the Minimum, Maximum, and Increment values. 7. Click OK. The Rating Table dialog box opens and displays the rating table. You can: –

Click Define Rating Table to change the setup for the table.

–

Click Print Preview to see how the table will look when printed.


4-123

Plot Rating Curves

4.7

Plot Rating Curves A rating curve shows how one or more (dependent) attributes change as another (independent) attribute is changed. For example, for a series of depths in a channel, you can show what the flow and velocity are. You might use rating curves (also called performance curves) to evaluate and show the performance of a design over a range of conditions that it might experience. You can plot one or more rating curves as graphs for each worksheet. You can plot either a single curve or a family of curves. To plot one or more rating curves: 1. Open the worksheet on which you want to base the rating table, and enter your data into it. 2. Click Solve to calculate the worksheet. 3. Click the worksheet dialog box for which you want to plot rating curves. 4. Click Analysis > Rating Curve or click the Rating Curve button. The Rating Curve Setup dialog box opens. 5. Choose the attribute to plot from the Plot and Vs. menus. The Plot attribute is the variable for the Y axis. The Vs. attribute is the variable for the X axis. 6. Enter the Minimum, Maximum, and Increment data for the Vs. attribute. 7. To plot a family of curves, select the Varying check box. Note that the attribute drop-down list and the associated Minimum, Maximum, and Increment fields become active. Select from the list and enter your data in the fields. 8. Click OK. The Rating Curve dialog box opens and displays the rating table. You can:

4-124

–

Click Define Rating Curve to change the setup for the table.

–

Click Print Preview to see how the curves will look when printed.

–

Click Chart Options to change the formatting and layout of the graphs. (For more information, see “Tutorial 3—Results Reporting” on page 2-17.)


How Do I…

4.8

Plot a Cross Section You can plot a cross-sectional diagram for each worksheet. 1. Open the worksheet on which you want to base the cross section, and enter your data into it. 2. Click Solve to calculate the worksheet. 3. Click the worksheet dialog box for which you want to plot the cross section. 4. Click Analysis > Cross Section or click the Cross Section button. The Cross Section Setup dialog box opens. 5. If you want to change the aspect ratio of the diagram, select the Manual Scale check box, then enter a value in the Aspect Ratio field. 6. If you want, enter a title for the cross section in the Report Title field. 7. Click OK. 8. Click OK. The Cross Section dialog box opens and displays the rating table. You can:

4.9

–

Click Print Preview to see how the cross section will look when printed.

–

Click Options to open the Cross Section Setup dialog box, so you can change the Manual Scale value or Report Title.

Print a Report Bentley FlowMaster lets you print a variety of reports. From the main view, you can print detailed reports and tabular reports for each worksheet. The detailed report contains all input data and results, along with all project information present in the Project Properties dialog box. To print a detailed report: 1. Open the worksheet for which you want to print a report, and enter your data into it. 2. Click Solve to calculate the worksheet. 3. Click the worksheet dialog box for which you want to print a report.


4-125

Customize a Tabular Report 4. Click Analysis > Detailed Report. This opens the Generic Report Setup dialog box, which lets you enter a name for the report. After you enter a name for the report and click OK, the Print Preview dialog box opens with the report displayed as it will be printed to the currently selected default printer. 5. In the Print Preview dialog box, click the Print button, select your printer, and click OK to print the report.

4.10

Customize a Tabular Report There are several ways to customize a tabular report: •

Change the report title—When you print a table, the table name is used as the title for the printed report. To change the title that appears on your printed report: a. Click the Options button in the Tabular Report dialog box. b. Type a new report title in the Report Title dialog box, then click OK. The new title will appear on the report the next time you click the Report button in the Tabular Report dialog box.

4-126

•

Add and remove columns—You can add, remove, and change the order of columns from the Tabular Report dialog box by clicking the Edit button. The Edit button displays the Tabular Report Setup dialog box, which lets you select which columns to include in the table. For more information, see “Tabular Report Setup Dialog Box” on page 3-111.

•

Move columns—You can drag and drop columns in a tabular report to change the order or columns. Select the column heading of the column that you would like to move, then use the mouse drag the column to its new location. A vertical separator line appears betweeen columns to indicate the selected column’s new location before you release the mouse button.

•

Resize columns—You can change the width of any column in a tabular report. Click the vertical separator line between column headings. Notice that the cursor changes shape to indicate that you can resize the column. Drag the column separator to the left or right to stretch the column to its new size.

•

Change column headings—Right-click the column heading that you wish to change and select Edit Column Label. Type the new column heading in the Edit Column Label dialog box, then click OK.

•

Copy data—You can copy the contents of the selected table cell, rows, and/or columns to the Windows clipboard, then paste the data into another application, such as Notepad or Microsoft Excel. Just select the cells, rows, or columns you want to copy, then click the Copy button.


How Do I…

4.10.1

•

Sort the contents of a table column—You can sort the contents of a table column by right-clicking the column heading and selecting one of the Sort commands. For more information, “Sort the Contents of a Column in a Tabular Report” on page 4127.

•

Filter the contents of a table—You can set up create custom filters to display only certain data in the table by right-clicking a column heading and selecting one of the Filter commands. For more information, “Filter the Contents of a Tabular Report” on page 4-128.

Sort the Contents of a Column in a Tabular Report To sort the contents of a column in a tabular report: 1. Open the tabular report you want to work with. 2. Right-click the heading of the column you want to sort, then select Sort. 3. Select the sorting method you want to use: –

Sort Ascending—Sorts alphabetically from A to Z, from top to bottom. Sorts numerically from negative to positive, from top to bottom. Sorts selected check boxes to the top and cleared ones to the bottom.

–

Sort Descending—Sorts alphabetically from Z to A, from top to bottom. Sorts numerically from positive to negative, from top to bottom. Sorts cleared check boxes to the top and selected ones to the bottom.

–

Custom—Specify one or more attributes by which to sort the contents of the selected column.

4. For a custom sort, specify the attribute(s) by which to sort the selected column in the Custom Sort dialog box. The Custom Sort dialog box contains a table in which you define one or more sort keys. A sort key contains two parts: –

Attribute—The attribute to sort. You can select any field in the tabular report from a drop-down list.

–

Sort Order—The order in which to sort the selected attribute’s values. Select Ascending or Descending.

Enter one or more sort keys. 5. Click OK.


4-127

Customize a Tabular Report

4.10.2

Filter the Contents of a Tabular Report To filter the contents of a tabular report: 1. Open the tabular report you want to filter. 2. Right-click the column heading you want to filter, then select Filter. 3. Then, select the filter method you want to use: –

Quick Filter—Set up a simple filter by right-clicking the column header for the attribute by which you wish to filter and selecting Filter > Quick Filter.

–

Custom Filter—Set up a custom filter based on one or more criteria.

–

Reset—Turn off the active filter, causing all available rows in the table to be displayed.

4. For Quick Filter or Custom Filter, specify your filtering criteria in the Filter dialog box. Each filter criterion is made up of three items: –

Column—The attribute used to filter.

–

Operator—The operator to use when comparing the filter value against the data in the specific column (operators include: =, >, >=, <, <=, < >, Contains, and Begins With).

Note:

The filtering options Contains and Begins With allow more flexibility with regard to filtering tables. These filters are only available for column types that have alphabetic values, for example Label. The Contains filter checks for the specified value anywhere in the words, and the Begins With filter checks only the first letter for the specified value.

–

Value—The comparison value. You can add any number of criteria to a filter. Multiple filter criteria are implicitly joined with a logical AND statement. When multiple filter criteria are defined, only rows that meet all of the specified criteria are displayed. A filter remains active for the associated table until the filter is reset.

5. Click OK.

4-128


How Do I…

4.11

Set Field Options (Unit, Precision, Format) Use the Set Field Options dialog box to change the units, display precision, and format used for each attribute in Bentley FlowMaster. You can mix SI (metric) and Imperial unit systems within the same worksheet. To open the Set Field Options dialog box: 1. Right-click the unit label next to the data field for the input or output variable to be changed. 2. Click the Units and Formatting. 3. In the Set Field Options dialog box that appears, change the units, precision, and formatting. For more information, see “Set Field Options Dialog Box” on page 3114.

4.12

Save a Project You can save a project as follows:

4.13

•

To save the current project without changing the name of the project or its path, you can click File > Save or, in the Project Explorer, right-click the project to be saved and select Save from the shortcut menu.

•

To save and change the name of the project and/or its path, you can click File > Save As or, in the Project Explorer, right-click the project to be saved and select Save As from the shortcut menu.

•

To save all currently open projects, click File > Save All.

Exit Bentley FlowMaster To exit Bentley FlowMaster, click File > Exit. If there are unsaved changes, a message will prompt you to save before exiting.


4-129

Exit Bentley FlowMaster

4-130


Chapter

5

Bentley FlowMaster Theory Bentley FlowMaster and its calculations are based on the principles outlined in this section:

5.1

•

“Uniform Flow” on page 5-131

•

“Critical Flow” on page 5-136

•

“Gradually Varied Flow Analysis” on page 5-148

•

“Weir Flow” on page 5-155

•

“Orifice Flow” on page 5-163

•

“Pressure Pipe” on page 5-164

•

“Inlet Hydraulics” on page 5-165

Uniform Flow The equations used in Bentley FlowMaster deal primarily with uniform flow. Uniform flow refers to a hydraulic condition in which the flow depth, channel discharge, and flow area do not change over a channel reach having constant section characteristics such as shape and material. These conditions are met only when the channel bottom slope and the friction slope are equal. When water is flowing under uniform flow conditions, the depth of flow is frequently called normal depth. Uniform flow can be described by the generalized friction equation:

V = CR x S y

(5.1)


5-131

Uniform Flow

Where

V

=

Mean velocity (m/sec., ft/sec.)

C

=

Flow resistance factor

R

=

Hydraulic radius (m, ft)

S

=

Friction slope (m/m, ft/ft)

x, y

=

Exponents

The material lining the flow channel usually determines the flow resistance or roughness factor, C. However, the ultimate value of the C component may be a function of the channel shape, depth, and velocity of flow. The hydraulic radius, R, is a strict function of the channel shape. For every geometric shape, R can be readily calculated by dividing the cross-sectional flow area by the wetted perimeter, once a depth is known or assumed. The energy slope, S, is constant under the uniform flow assumption. Since average velocity is constant under uniform flow (constant discharge and area conditions), combining equation 5.1 with the continuity equation: Q = VA

(5.2)

results in the equation: Q = ACRxSy Where

(5.3)

Q

=

Discharge (m3/sec., ft3/sec.)

A

=

Cross-sectional flow area (m3, ft3 )

This solution yields a complete solution for the rate of flow. Note:

Hydraulic radius is related to flow area, so further reduction of this equation for specific geometries is often possible.

Bentley FlowMaster offers the four variations of the general uniform flow equation listed below. These equations differ from each other by the computation and nature of C and in the values assigned to x and y.

5-132

•

“Manning’s Formula”

•

“Kutter’s Formula”

•

“Hazen-Williams Formula”

•

“Darcy-Weisbach Formula”


Bentley FlowMaster Theory

5.1.1

Manning’s Formula Manning’s formula is probably the most widely used open channel flow equation, and is one of the easiest equations to solve. The roughness component, C, is constant over the full range of flows and is typically represented by Manning’s n. The values of x and y are 2/3 and 1/2, respectively. Equations for U.S. customary and the S.I. system units are shown below.

V=

V=

Where

5.1.2

1 2 / 3 1/ 2 R S n S.I. Units

(5.4)

1.49 2 / 3 1 / 2 R S n U.S. Customary Units

(5.5)

V

=

Mean velocity (m/sec., ft/sec.)

n

=

Manning’s coefficient

R

=


S

=


Kutter’s Formula The standard form of Kutter’s Formula is known as the Chézy Formula. Kutter’s Formula is widely used in sanitary sewer design and analysis. The roughness component, C, is variable and is a function of R, S, and the channel material. Both x and y are equal to 1/2. Equations for U.S. customary units and the S.I. system are shown below:

V = C RS

(5.6)

The roughness coefficient C is related to Manning’s n through Kutter’s formula.


5-133

Uniform Flow Note:

Kutter’s roughness coefficients are the same as Manning’s roughness coefficients.

k 2 k3 + S n C= n k k1 + 2 1+ Sł R Ł k1 +

Where

5.1.3

(5.7)

C

=

Chézy’s roughness coefficient (m1/2/sec., ft1/2/ sec.)

S

=


R

=

Hydraulic radius (m,ft)

n

=

Kutter’s roughness (unitless)

k1

=

Constant (23.0 SI, 41.65 U.S. customary)

k2

=


k3

=


Hazen-Williams Formula The Hazen-Williams Formula is most frequently used in the design of pressure pipe systems for water distribution. The roughness coefficient, C, is constant over the full range of flows (assumed turbulent). The values of x and y in this empirical equation are 0.63 and 0.54. Equations for U.S. customary and the S.I. units are shown below.

5-134

V = 0.85CR 0.63 S 0.54 S.I. Units

(5.8)

V = 1.32CR 0.63 S 0.54 U.S. Customary Units

(5.9)



5.1.4

Darcy-Weisbach Formula The Darcy-Weisbach Formula was developed for use in the analysis of pressure pipe systems. However, the formula is sufficiently general so that it can be applied readily to open channel flow systems. In fact, the ASCE Task Force on Friction Factors in Open Channels (1963) supported the use of the Darcy-Weisbach formula for freesurface flows. This recommendation has not been widely accepted since the solution to the equation is difficult, and not readily computed by simple desktop methods. With the computerization of this method, the Darcy-Weisbach Formula will likely gain greater acceptance, since it successfully models the variability of effective channel roughness with channel material, geometry, and velocity. Thus, many engineers view this formula as the most accurate method for modeling uniform flow. The roughness component in the Darcy-Weisbach equation is a function of both the channel material and the Reynolds Number, which varies with V and R. Like Kutter’s Equation, both x and y are equal to 1/2. The familiar form of the equation, which is applicable to circular pipes with full flow only, is:

L V2 D 2g

hf = f

Where

(5.10)

hf

=

Headloss (m, ft)

f

=

Darcy-Weisbach friction factor

D

=

Pipe diameter (m, ft)

L

=

Pipe length (m, ft)

V

=

Flow velocity (m/sec., ft/sec.)

g

=

Gravitational acceleration (m/sec.2, ft/sec.2 )

This equation is adapted for channel geometries other than full circular by the relation: D = 4R

(5.11)

and then rearranged to the form:

V=

8g RS f


(5.12)

5-135

Critical Flow The Darcy-Weisbach friction factor (f) can be found using the Colebrook equation for fully developed turbulent flow. Roughness height, k, is a physical property of the channel material. Equations for free surface and full flow closed conduits are shown below.

1 f

= - 2 log

k 2.51 + Ł12 R Re f ł

Free Surface

k 2.51 1 = - 2 log + f Ł14.8 R Re f ł Where

5.2

Full-Flow Closed Conduits

Re

=

Reynold’s number (unitless)

k

=

Roughness height (m, ft)

(5.13)

(5.14)

Critical Flow Critical flow conditions occur when, for a given discharge, the specific energy of flow is at a minimum. The specific energy, E, in Bentley FlowMaster is computed using the equation:

E = y+

Where

V2 2g

(5.15)

y

=

Flow depth (m, ft)

V

=

Velocity (m/sec., ft/sec.)

g

=


The quantity V2/2g is also known as the velocity head. The specific energy equation used in Bentley FlowMaster is valid only for small slopes (< 10%). It also neglects the effects of the velocity variation across the flow section; that is, the velocity coefficient, a, is assumed to equal 1.0. At critical depth, the velocity of flow is also equal to the wave celerity (i.e. the speed at which waves will ripple outward from a pebble which is tossed into the water). The Froude number, F, is defined as the ratio of actual velocity to wave celerity. This number is only defined for sections that have a free surface; it is undefined for closed conduits or closed top irregular channels when flowing full.

5-136


Bentley FlowMaster Theory The ratio is:

F=

Where

V gD

(5.16)

D

=

Hydraulic depth of channel is equivalent to A/T (m, ft)

A

=

Flow area (m2, ft2)

T

=

Top width of flow (m, ft)

When F is less than one, the flow is said to be subcritical (velocity slower than wave celerity). When F is greater than one, the flow is said to be supercritical (velocity faster than wave celerity). When F is equal to one, the flow is said to be critical. A diagram showing these flow ranges appears below.

Figure 5-1: Specific Energy Curve The requirement that wave celerity equals actual velocity at critical flow conditions means that critical depth can be computed by varying depth of flow until F equals 1.0. Specifically, Bentley FlowMaster uses the following function, and solves by iterating over depth until f (y) = 0:

f ( y ) = gA3 - Q 2T


(5.17)

5-137

Critical Flow

5.2.1

Basic Concepts of Critical Flow This section is intended to familiarize you with some of the methods used in this program’s calculations. However, the text does not go into great detail on common hydraulic terms and equations, such as determination of wetted perimeter, hydraulic radius, hydraulic depth, and Reynolds number.

5.2.2

Hydraulic and Energy Grades Bentley FlowMaster considers the following hydraulic and energy grade principles: •

“The Energy Principle” on page 5-138

•

“The Energy Equation” on page 5-139

•

“Hydraulic Grade” on page 5-140

•

“Energy Grade” on page 5-140

•

“HGL Convergence Test” on page 5-140

The Energy Principle The first law of thermodynamics states that for any given system, the change in energy is equal to the difference between the heat transferred to the system and the work done by the system on its surroundings during a given time interval. The energy referred to in this principle represents the total energy of the system minus the sum of the potential, kinetic, and internal (molecular) forms of energy, such as electrical and chemical energy. The internal energy changes are commonly disregarded in water distribution analysis because of their relatively small magnitude. In hydraulic applications, energy is often represented as energy per unit weight, resulting in units of length. Using these length equivalents gives engineers a better feel for the resulting behavior of the system. When using these length equivalents, the state of the system is expressed in terms of head. The energy at any point within a hydraulic system is often represented in three parts:

5-138

Pressure head: p/γ

(5.18)

Elevation head: z

(5.19)

Velocity head: V2/2g

(5.20)



Where

p

=

Pressure (N/m2, lb/ft2 )

γ

=

Specific weight (N/m3, lb/ft3 )

z

=

Elevation (m, ft)

V

=


g

=

Gravitational acceleration (m/sec.2, ft/sec.2)

These quantities can be used to express the headloss or head gain between two locations using the energy equation.

The Energy Equation In addition to pressure head, elevation head, and velocity head, there may also be head added to the system, by a pump for instance, and head removed from the system due to friction. These changes in head are referred to as head gains and headlosses, respectively. Balancing the energy across two points in the system, we then obtain the energy equation:

p V2 p1 V2 + z1 + 1 + hp = 2 + z2 + 2 + H L g 2g g 2g Where

p

=


γ

=


z

=

Elevation at the centroid (m, ft)

V

=


g

=


hp

=

Head gain from pump (m, ft)

HL

=

Combined headloss (m, ft)

(5.21)

The components of the energy equation can be combined to express two useful quantities, which are the hydraulic grade and the energy grade.


5-139

Critical Flow

Hydraulic Grade The hydraulic grade is the sum of the pressure head (p/γ) and elevation head (z). The hydraulic head represents the height to which a water column would rise in a piezometer. The plot of the hydraulic grade in a profile is often referred to as the hydraulic grade line, or HGL.

Energy Grade The energy grade is the sum of the hydraulic grade and the velocity head ( V2/2g ). This is the height to which a column of water would rise in a pitot tube. The plot of the hydraulic grade in a profile is often referred to as the energy grade line, or EGL. At a lake or reservoir, where the velocity is essentially zero, the EGL is equal to the HGL, as can be seen in the following figure.

Figure 5-2: Plot of EGL and HGL

HGL Convergence Test In full network calculation this value is taken as the maximum absolute change between two successive solves of hydraulic grade at any junction or inlet in the system. This test is used to optimize the performance of system solutions. It minimizes the number and extent of hydraulic grade line computations in the upstream direction. For a given discharge, the upstream propagation of headlosses through pipes will continue until two successive calculations change by an absolute difference of less than this test value.

5-140


Bentley FlowMaster Theory The HGL Convergence Test value is also used in the standard step gradually varied flow profiling algorithm. If two successive depth iterations are within this absolute test value, the step is solved.

5.2.3

Friction Loss Methods There are many equations that approximate friction losses associated with the flow of liquid through a given section. Commonly used friction methods include: •

“Chézy’s Equation”

•

“Kutter’s Equation”

•

“Manning’s Equation”

•

“Darcy-Weisbach Equation”

•

“Swamee and Jain Equation”

•

“Colebrook-White Equation”

•

“Hazen-Williams Equation”

Friction losses are generally based on the relationships between fluid velocity, section roughness, depth of flow, and the friction slope (headloss per unit length of conduit).

Chézy’s Equation Chézy’s equation is rarely used directly, but it is the basis for several other methods, including Manning’s equation and Kutter’s equation. Chézy’s equation is:

Q= C A Where

R S

(5.22)

Q

=

Discharge in the section (m3/sec., ft3/sec.)

C

=


A

=

Flow area (m2, ft2 )

R

=


S

=



5-141

Critical Flow

Kutter’s Equation Kutter’s equation can be used to determine the roughness coefficient in Chézy’s formula, and is most commonly used for sanitary sewer analysis. Kutter’s equation is as follows: Note:

Kutter’s roughness coefficients are the same as Manning’s roughness coefficients.

k 2 k3 + S n C= n k k1 + 2 1+ Sł R Ł k1 +

Where

(5.23)

C

=


S

=


R

=

Hydraulic roughness (unitless)

n

=

Kutter’s roughness (unitless)

k1

=


k2

=


k3

=


Manning’s Equation Manning's equation is one of the most popular methods in use today for free surface flow (and, like Kutter’s equation, is based on Chézy’s equation). For Manning’s equation, the roughness coefficient in Chézy’s equation is calculated as:

R1/ 6 C= k n

5-142

(5.24)



Where

C

=


R

=


n

=

Manning’s roughness (sec./m1/3 )

k

=

Constant (1.00m1/3/m1/3 SI, 1.49 ft1/3/ft1/3 U.S. customary)

Substituting this roughness into Chézy’s equation, we obtain the well-known Manning’s equation: Note:

Manning’s roughness coefficients are the same as the roughness coefficients used in Kutter’s equation.

Q= Where

k A R 2 / 3 S 1/ 2 n

(5.25)

Q

=

Discharge (m3/sec., ft3/sec.)

k

=

Constant (1.00m1/3/m1/3 SI, 1.49ft1/3/ft1/3 U.S. customary)

n

=

Manning’s coefficient (unitless)

A

=


R

=


S

=


Darcy-Weisbach Equation Because of non-empirical origins, the Darcy-Weisbach equation is viewed by many engineers as the most accurate method for modeling friction losses. It most commonly takes the following form:

L V2 hf = f D 2g


(5.26)

5-143

Critical Flow

Where

hf

=

Headloss (m, ft)

f

=

Darcy-Weisbach friction factor (unitless)

D

=


L

=

Pipe length (m, ft)

V

=

Flow velocity (m/sec., ft/sec.)

g

=


For section geometries that are not circular, this equation is adapted by relating a circular section’s full flow hydraulic radius to its diameter:

A3 Q 2 = T g Where

(5.27)

A

=

Area of flow (m2, ft2 )

T

=


Q

=

Section discharge (m3/sec., ft3/sec.)

g

=


This can then be rearranged to the form:

Q= A

Where

5-144

8g

R S f

(5.28)

Q

=


A

=


R

=


S

=


f

=

Darcy-Weisbach friction factor (unitless)

g

=



Bentley FlowMaster Theory The Swamee and Jain equation can then be used to calculate the friction factor.

Swamee and Jain Equation Note:

The Kinematic Viscosity is used in determining the friction coefficient in the Darcy-Weisbach Friction Method. The default units are initially set by Bentley Systems.

The friction factor is dependent on the Reynolds number of the flow, which is dependent on the flow velocity, which is dependent on the discharge. As you can see, this process requires the iterative selection of a friction factor until the calculated discharge agrees with the chosen friction factor.

f=

Where

1.325 Ø ø2 Œln k + 5.74 0.9 œ Œ Ł 3.7 D Re łœ º ß

(5.29)

f

=

Friction factor (unitless)

k

=

Roughness height (m, ft)

D

=


Re

=

Reynolds number (unitless)

Colebrook-White Equation The Colebrook-White equation is used to iteratively calculate for the Darcy-Weisbach friction Factor:

1 k 2.51 = - 2 log + f Ł14.8 R Re f ł

Free Surface

1 k 2.51 = - 2 log + f Ł12.0 R Re f ł Full Flow (Closed Conduit)


(5.30)

(5.31)

5-145

Critical Flow

Where

Re

=

Reynolds number (unitless)

k

=

Darcy-Weisbach roughness height (m, ft)

f

=

Friction factor (unitless)

R

=


Hazen-Williams Equation The Hazen-Williams Formula is frequently used in the analysis of pressure pipe systems (such as water distribution networks and sewer force mains). The formula is as follows:

Q = k C A R 0.63 S 0.54 Where

Q

=

C

5.2.4

(5.32)

Section discharge (m3/sec., ft3/sec.) Hazen-Williams roughness coefficient (unitless)

A

=


R

=


S

=


k

=


Flow Regime Note:

Based on the gradually varied flow analysis, different portions of any given pipe may be under different flow regimes.

The hydraulic grade in a flow section depends heavily on the tailwater conditions, pipe slope, discharge, and other conditions. The basic flow regimes that a pipe may experience include:

5-146

•

“Pressure Flow”

•

“Uniform Flow and Normal Depth”

•

“Critical Flow, Critical Depth, and Critical Slope”

•

“Subcritical Flow”

•

“Supercritical Flow”



Pressure Flow When a pipe is surcharged, headlosses are based on the full barrel area and wetted perimeter. Because these characteristics are all functions of the section shape and size, friction loss calculations are greatly simplified by pressurized conditions.

Uniform Flow and Normal Depth Uniform flow refers to a hydraulic condition where the discharge and cross-sectional area, and therefore the velocity, are constant throughout the length of the channel or pipe. For a pipe flowing full, all that this requires is that the pipe be straight and have no contractions or expansions. For a non-full section, however, there are a few additional points of interest: •

In order for the cross-sectional area to remain the same, the depth of flow must be constant throughout the length of the channel. This requires that the friction slope equal the constructed slope. This depth is called normal depth.

•

Since the hydraulic grade line parallels the invert of the section and the velocity does not change, the energy grade line is parallel to both the hydraulic grade line and the section invert under uniform flow conditions.

In prismatic channels, flow conditions will typically approach normal depth if the channel is sufficiently long.

Critical Flow, Critical Depth, and Critical Slope Critical flow occurs when the specific energy of the section is at a minimum. This condition is defined by the situation where:

A3 Q 2 = T g Where

(5.33)

A

=


T

=


Q

=


g

=


This is a relatively simple computation for simple geometric shapes, but can require iterative calculation for more complex shapes (such as arches). Some sections may even have several valid critical depths, making numerical convergence more difficult.


5-147

Gradually Varied Flow Analysis Critical depth refers to the depth of water in a channel for which the specific energy is at its minimum. Critical slope refers to the slope at which the critical depth of a pipe would be equal to the normal depth. Subcritical Flow Subcritical flow refers to any flow condition where the Froude number is less than 1.0. For this condition, the depth is above critical depth, and the velocity is below the critical depth velocity. Supercritical Flow Supercritical flow refers to any condition where the Froude number, or the ratio of internal forces to gravity forces, is greater than 1.0. For this condition, the depth is below critical depth, and the velocity is above the critical depth velocity.

5.3

Gradually Varied Flow Analysis For free surface flow, depth rarely remains the same throughout the length of a channel or pipe. Starting from a boundary control depth, the depth changes gradually, increasing or decreasing until normal depth is achieved (if the conduit is sufficiently long). The determination of a boundary control depth depends on both the tailwater condition and the hydraulic characteristics of the conduit. The areas of classification for gradually varied flow analysis are:

5.3.1

•

Slope Classification

•

Zone Classification

•

Profile Classification

Slope Classification The constructed slope of a conduit is a very important factor in determining the type of gradually varied flow profile that exists. Slopes fall into one of three types, all of which are handled by the program:

5-148

•

Hydraulically Mild Slope

•

Critical Slope

•

Hydraulically Steep Slope


Bentley FlowMaster Theory Any pipe can qualify as only one of these slope types for a given discharge. For differing flows, though, a pipe may change between qualifying as a mild, critical, and steep slope. These slopes do not relate to just the constructed slope, but to the constructed slope relative to the critical slope for the given discharge.

5.3.2

Hydraulically Steep Slope A hydraulically steep slope is a condition where the constructed slope is greater than the critical slope. For this condition, the section’s normal depth is below critical depth, and the flow regime is usually supercritical. However, high tailwater conditions may cause flow to be subcritical.

5.3.3

Critical Slope A pipe or channel may have exactly the same slope as the critical slope for the discharge it carries. This is a very uncommon occurrence, but it is possible and the program does calculate it appropriately. Critical depth is an inherently unstable surface, so flow is most likely to be subcritical for these slopes.

5.3.4

Hydraulically Mild Slope A hydraulically mild slope is a condition where the constructed slope is less than the critical slope. For this condition, the section’s normal depth is above critical depth, and the flow regime is usually subcritical.

5.3.5

Zone Classification There are three zones that are typically used to classify gradually varied flow:

5.3.6

•

Zone 1 is where actual flow depth is above both normal depth and critical depth.

•

Zone 2 is where actual flow depth is between normal depth and critical depth.

•

Zone 3 is where actual flow depth is below both normal depth and critical depth.

Profile Classification The gradually varied flow profile classification is a combination of the slope classification and the zone classification. For example, a pipe with a hydraulically mild slope and flow in zone 1 would be considered a mild-1 profile (M1 for short). The program will analyze most profile types, but will not analyze certain flow profile types that occur rarely in conventional sewer system such as H3, M3, and S3.


5-149

Gradually Varied Flow Analysis The following diagrams describe the various profile classifications.

Zone 1 Profiles y > yn; y > yc

yn yc

Unsealing Conjugate

yn' yn yc

Mild Type II Q Q

Slug Sealing Conj.

yc yn' yn

yc yn' yn

Q

max

Conjugate

yn' yn yc

M1 Slug

full

Mild Type I Q < Qfull

M1

S1

Unsealing Conjugate

yc yn

yn' yc yn

Horizontal Slope

H1 None

H2

H3

yc

yc

A1 None

A2

A3

yc

yc

yc

Steep Slope yn< yc

5-150

yc,n

Adverse Slope

Critical Slope yn= yc

C1

yc



Zone 3 Profiles


M2 yn yc

Mild Type II Q Q

full

M2 Slug Conjugate

M3 yn yc

M3 Slug yc yn' yn

Q

max

yc yn' yn

Horizontal Slope

yn

H2

H2

yc

yc

Adverse Slope

yn' yc yn

S2 yc

A2

A2

yc

yc

C3 yc,n

S3 yc yn

Horizontal Slope

yc,n

Steep Slope yn< yc


C2 Unstable

S2 Slug Conjugate

Steep Slope yn< yc

y < yn; y < yc

H3

Adverse Slope


max

Mild Type II Q Q Q

full


Zone 2 Profiles yn y y c; y n y c y

A3

yc

yc

Figure 5-3: Profile Classification


5-151

Gradually Varied Flow Analysis

5.3.7

Energy Balance Even for gradually varied flow, the solution is still a matter of balancing the energy between the two ends of a pipe segment. The energy equation as it relates to each end of a segment is as follows (note that the pressures for both ends are zero, since it is free surface flow):

Z1 + Where

V12 V2 = Z2 + 2 + H L 2g 2g

(5.34)

Z1

=

Hydraulic grade at upstream end of segment (m, ft)

V1

=

Velocity at upstream end (m/sec., ft/sec.)

Z2

=

Hydraulic grade at downstream end of segment (m, ft)

V2

=

Velocity at downstream end (m/sec., ft/sec.)

HL

=

Loss due to friction—other losses assumed to be zero (m, ft)

g

=


The friction loss is computed based on the average rate of friction loss along the segment and the length of the segment. This relationship is as follows:

H L = S Avg D x = Where

5-152

S1 + S2 Dx 2

(5.35)

HL

=

Loss across segment (m, ft)

SAVG

=

Average friction slope (m/m, ft/ft)

S1

=

Friction slope at upstream end of segment (m/m, ft/ft)

S2

=

Friction slope at downstream end of segment (m/ m, ft/ft)

∆x

=

Length of segment being analyzed (m, ft)


Bentley FlowMaster Theory The conditions at one end of the segment are known through assumption or from a previous calculation step. Since the friction slope is a function of velocity, which is a function of depth, the depth at the other end of the segment can be found through iteration. There are two primary methods for this iterative solution, the Standard Step method and the Direct Step method.

Standard Step Method The standard step method of gradually varied flow energy balance involves dividing the channel into segments of known length and solving for the unknown depth at one end of the segment, starting with a known or assumed depth at the other end. The standard step method is the most popular method of determining the flow profile because it can be applied to any channel, not just prismatic channels.

Direct Step Method The direct step method is based on the same basic energy principles as the standard step method, but takes a slightly different approach towards the solution. Instead of assuming a segment length and solving for the depth at the end of the segment, the direct step method assumes a depth and then solves for the segment length.

5.3.8

Mixed Flow Profiles Although the hydraulic slope of a pipe will be the same throughout its length, a pipe may contain several different profile types. The transitions that may be encountered include: •

“Sealing (Surcharging) Conditions”

•

“Rapidly Varied Flow”

Sealing (Surcharging) Conditions There may be conditions such that part of the section is flowing full, while part of the flow remains open. These conditions are called sealing conditions, and the sections are analyzed in separate parts. For sealing conditions, the portion of the section flowing full is analyzed as pressure flow, and the remaining portion is analyzed with gradually varied flow techniques.

Rapidly Varied Flow Rapidly varied flow is turbulent flow resulting from the abrupt and pronounced curvature of flow streamlines into or out of a hydraulic control structure. Examples of rapidly varied flow include hydraulic jumps, bends, and bridge contractions.


5-153

Gradually Varied Flow Analysis The hydraulic phenomenon that occurs when the flow passes rapidly from supercritical to subcritical flow is called a hydraulic jump. The most common occurrence of this within a gravity flow network occurs when there is a steep pipe discharging into a particularly high tailwater, as shown in the following figure.

Figure 5-4: Hydraulic Jump There are significant losses associated with hydraulic jumps, due to the amount of mixing and hydraulic turbulence that occurs. These forces are also highly erosive, so engineers typically try to prevent jumps from occurring in gravity flow systems, or at least try to predict the location of these jumps in order to provide adequate channel, pipe, or structure protection. The program does not perform any specific force analyses that seek to precisely locate the hydraulic jump, nor does it identify the occurrence of jumps that might happen as flows leave a steep pipe and enter a mild pipe. Rather it performs analyses sufficient to compute grades at structures.

5.3.9

Backwater Analysis The classic solution of gravity flow hydraulics is via a backwater analysis. This type of analysis starts at the network outlet under free discharge, submerged, or tailwater control, and proceeds in an upstream direction. Steep pipes tend to interrupt the backwater analysis, and reset the hydraulic control to critical depth at the upstream end of the steep pipe. A frontwater analysis may be needed for a steep profile (such as an S2), with the backwater analysis recommencing from the upstream structure. Certain situations are considered to be invalid downstream control by Bentley FlowMaster. The following criteria must be met to enable a valid downstream control: Note:

5-154

An error message will be displayed if the input data does not satisfy these requirements.

•

Mild Case: Normal Depth Greater Than Or Equal To Critical Depth

•

Steep Case: Critical Depth Greater Than Or Equal To Normal Depth

•

Critical Slope: Critical Depth Equal To Normal Depth



5.3.10

Frontwater Analysis The program will perform a frontwater analysis in a steep pipe operating under supercritical flow, since these pipes are typically entrance controlled. The hydraulic control is at the upstream end of the conduit, and the gradually varied flow analysis will proceed in a downstream direction until either the normal depth is achieved, a hydraulic jump occurs, or the end of the pipe is encountered. Note:

The program’s algorithm is fundamentally based on backwater analysis. As a result, a continuous frontwater analysis is not performed through two or more consecutive steep pipes. This is a performance trade-off that has little impact in evaluating performance of the collection system in most situations. The assumption of critical depth at the upstream end results in a conservative depth in all cases, and is exactly correct at the point of the steep run furthest upstream.

Certain situations are considered to be invalid upstream control by Bentley FlowMaster.The following criteria must be met to enable a valid downstream control:

5.4

•

Mild Case: Depth Less Than Or Equal To Normal Depth

•

Steep Case: Normal Depth Greater Than Or Equal To Critical Depth

•

Critical Slope: Critical Depth Equal To Normal Depth

Weir Flow Sharp-crested and non-sharp-crested weirs are the two profiles generally associated with weir flow. Sharp-crested weirs are usually used for measuring a discharge, based on the water height. Non-sharp-crested weirs are usually part of a hydraulic structure, such as an overflowing embankment or roadway.

5.4.1

Sharp-Crested Weirs A sharp-crested weir has a sharp upstream edge formed so that the water flows clear of the crest. Bentley FlowMaster handles weir calculations for unsubmerged (free discharge) and submerged (backwater effect) sharp-crested weirs.


5-155

Weir Flow

Rectangular Sharp-Crested Weir Note:

An error message will be displayed if the input data does not satisfy these requirements.

L

H

Figure 5-5: Rectangular Sharp-Crested Weir The discharge over an unsubmerged rectangular sharp-crested weir is defined as:

Q = C (L - 0.1iH )H 3 2 Where

(5.36)

Q

=

Discharge over weir (m3/sec., ft3/sec.)

C

=

Weir coefficient (typical values for this kind of weir are C = 1.84 SI and C = 3.33 U.S. customary)

L

=

Weir opening width (m, ft)

i

=

Number of contractions (i = 0, 1, or 2)

H

=

Head above bottom of opening (m, ft)

i = 0 corresponds to the case of a suppressed rectangular weir, for which the channel width is equal to the weir opening length, and yields the equation:

Q = CLH 3 2

(5.37)

i = 2 corresponds to the case of a contracted rectangular weir.

5-156



V-Notch Sharp-Crested Weir

H

0

Figure 5-6: V-Notch Sharp Crested Weir The discharge over an unsubmerged V-Notch sharp-crested weir is defined as:

Q= C

Where

8 Q 2 g tan H5 2 Ł2 ł 15

(5.38)

Q

=


C

=

Coefficient of discharge (C = 0.58 typically used for a 90° V-notch weir)

Θ

=

Angle of notch (degrees)

H

=

Head above bottom of notch (m, ft)

Table 5-1: V-Notch Weir Coefficient of Discharge Head (feet)

Weir Angle (degrees) 22.5

30

45

60

90

120

0.5

.611

.605

.596

.590

.584

.581

1.0

.593

.590

.583

.580

.576

.575

1.5

.586

.583

.578

.575

.572

.672

2.0

.583

.580

.576

.573

.571

.571

2.5

.580

.578

.574

.572

.570

.570

3.0

.579

.577

.574

.571

.570

.570


5-157

Weir Flow Coefficients for sharp-crested V-notched weirs vary with the angle of the notch and with head depth. For detailed discussion on discharge coefficients for various weir configurations, review the references noted at the bottom of this page.1 2 3

Cipolletti Sharp-Crested Weir

L

H

Figure 5-7: Cipoletti Sharp-Crested Weir Cipolletti weirs are trapezoidal with 1:4 slopes to compensate for end contraction losses. The equation generally accepted for computing the discharge through an unsubmerged sharp-crested Cipolletti weir with complete contraction is: Note:

1.84 and 3.367 are standard values only.

Q = 1.84 LH 3 2 S.I. Units

(5.39)

Q = 3.367 LH 3 2 U.S. Customary Units

(5.40)

Where

Q

=


L

=

Bottom of notch width

H

=

Head above bottom of opening (m, ft)

1. Brater, Ernest F. and Horace Williams King, Handbook of Hydraulics, McGraw-Hill Book Company, New York, 1976. 2. Shen, John, Discharge Characteristics of Triangular Notch Thin-Plate Weirs, Geological Survey Water-Supply Paper 1617-B, U.S Dept. of Interior, 1981. 3. Derived from table in: Van Haveren, Bruce P., Water Resource Measurements, American Water Works Assoc.,1986.

5-158



Submerged Sharp-Crested Weir

H2

H1

Figure 5-8: Submerged Sharp-Crested Weir If the sharp-crested weir is submerged as illustrated in the figure above (with H2 > 0), then the flow Q1 that would be obtained without submergence, using one of the equations above, is corrected as follows to obtain the flow Q over the weir1: 0.385 nø Ø H2 œ Œ Q = Q1 Œ1œ Œ ŁH1 ł œ ß º

Where

(5.41)

Q

=


Q1

=

Discharge over weir opening that would be obtained without submergence at head H1 (m3/ sec., ft3/sec.)

H1

=

Head above weir crest (m, ft)

H2

=

Downstream head above weir (m, ft)

n

=

Exponent in corresponding weir equation with no submergence (3/2 or 5/2 in cases above)

1. Brater, Ernest F. and Horace Williams King, Handbook of Hydraulics, McGraw-Hill Book Company, New York, 1976.


5-159

Weir Flow

5.4.2

Non-Sharp-Crested Weirs For the following types of weirs, the weir coefficients are strongly dependent on the weir shape, width (measured in the flow direction) and the upstream head. It is recommended to use values from a reference book as a starting point, and when possible, calibrate these coefficients.

Broad-Crested Weir A broad-crested weir has a crest that extends horizontally in the direction of flow far enough to support the nappe (sheet of water flowing over the crest of the weir) so that hydrostatic pressures are fully developed for at least some short distance. In order to model Embankment or Roadway overtopping, the Federal Highway Administration (FHWA) has developed a methodology that can be found in the manual FHWA, HDS No. 5, Hydraulic Design of Highway Culverts, 1985, which uses the general broad-crested weir equation.

Q = Cd LH r3 2 Where

(5.42)

Q

=


Cd

=

Weir coefficient

L

=

Length of roadway crest (m, ft)

Hr

=

Overtopping depth (m, ft)

Hr

ht Lr

Figure 5-9: Broad-Crested Weir The overtopping discharge coefficient Cd is a function of the submergence using the equation:

Cd = K t Cr

5-160

(5.43)


Bentley FlowMaster Theory The variables Kt and Cr are defined in the following figures, reproduced from the manual FHWA, HDS No.5, Hydraulic Design of Highway Culverts, 1985. The first two figures are used by Bentley FlowMaster to derive the base weir coefficient Cr resulting from deep and shallow overtopping, respectively. The submergence correction Kt is determined implicitly using the third figure.

Figure 5-10: Discharge Coefficient Cr, for Hr/L > 0.15

Figure 5-11: Discharge Coefficient Cr, for Hr/L ≤ 0.15


5-161

Weir Flow

Figure 5-12: Submergence Factor, k

Triangular and Trapezoidal Weir The discharge over a triangular or trapezoidal weir is:

Q = CLH 3 2 Where

(5.44)

Q

=


C

=

Weir coefficient

L

=

Weir length (m, ft)

H

=

Head above weir crest (m, ft)

Model these weirs by using the Generic Weir in Bentley FlowMaster, entering the appropriate coefficient. The weir coefficient is a function of the upstream head and the shape of the weir.

5-162



5.5

Orifice Flow H For free outfall, measure H from centroid

Figure 5-13: Orifice Flow (schematic) The orifice equation is defined as:

Q = CA 2 gH Where

5.5.1

(5.45)

Q

=

Flow (m3/sec., ft3/sec.)

C

=

Orifice coefficient

A

=


g

=


H

=

Head (m, ft)

Orifice Coefficients Although these coefficients vary with shape, size, and head depth, an average C coefficient of 0.60 is often used for storm water orifice openings. A list of orifice coefficients for various heads and sizes of circular, square, rectangular, and triangular shapes can be found in the Handbook of Hydraulics, by Brater et Al. (see References).

Sluice Gate Gates have the hydraulic properties of orifices. Therefore, the discharge through a sluice gate is:

Q = CA 2 gH


(5.46)

5-163

Pressure Pipe

Where

Q

=

Flow (m3/sec., ft3/sec.)

C

=

Orifice coefficient

A

=


g

=


H

=

Head (m, ft)

Model a sluice gate by using the Generic Orifice in Bentley FlowMaster, entering the appropriate coefficient.

5.6

Pressure Pipe In hydraulic applications, energy is often converted into units of energy per unit weight, resulting in units of length. Using these length equivalents gives engineers a better “feel” for the resulting behavior of the system. When using these length equivalents, the user is expressing the state of the system in terms of head. The energy at any point within a hydraulic system is often represented in three parts: Pressure head: p/γ

(5.47)

Elevation head: z

(5.48)

Velocity head: V2/2g

(5.49)

Where

p

=


γ

=


z

=

Elevation (m, ft)

V

=


g

=


Balancing the energy at the two ends of a pressure pipe, the energy equation can be reduced to:

p1 p + z1 = 2 + z2 + hL g g

5-164

(5.50)



Where

5.6.1

hL

=

Friction headloss (m, ft)

Hydraulic Grade and Energy Grade The hydraulic grade is the sum of the pressure head (p/γ) and elevation head (z). The hydraulic head represents the height to which a water column would rise in a piezometer. The plot of the hydraulic grade in a profile is often referred to as the hydraulic grade line, or HGL. The energy grade is the sum of the hydraulic grade and the velocity head (V2/2g). This is the height to which a column of water would rise in a pitot tube. The plot of the hydraulic grade in a profile is often referred to as the energy grade line, or EGL.

5.7

Inlet Hydraulics Bentley FlowMaster considers the following inlet hydraulic principles: •

“HEC-22 Inlet Comparison” on page 5-166

•

“Flows in Gutters on Grade” on page 5-166

•

“Flow in Ditch or Median Section on Grade” on page 5-170

•

“Inlet Analysis” on page 5-171

•

“Grate Inlet on Grade” on page 5-173

•

“Curb Inlet on Grade” on page 5-175

•

“Slot Inlet on Grade” on page 5-177

•

“Combination Inlet on Grade” on page 5-177

•

“Grate Inlet in Sag” on page 5-178

•

“Curb Inlet in Sag” on page 5-179

•

“Slot Inlet in Sag” on page 5-182

•

“Combination Inlet in Sag” on page 5-183


5-165

Inlet Hydraulics

5.7.1

HEC-22 Inlet Comparison Note:

Pavement drainage requires consideration of gutter flow and inlet capacity. The design of these elements is dependent on storm frequency and the allowable spread of storm water on the pavement surface. Bentley FlowMaster performs hydraulic computations for analyzing or sizing one inlet at a time. For analyzing or designing an entire storm sewer network, Bentley Systems offers StormCAD, which also follows the HEC-22 methodology for inlet computations.

The methodology used by Bentley FlowMaster to perform pavement drainage and inlet computations is described in Chapter 4 of the HEC-22 manual: Urban Drainage Design Manual, 1996. This chapter is included as “Pavement Drainage” on page 6185. Related charts can be found in “Engineer’s Reference” on page 8-309. Most of the information presented in HEC-22 Chapter 4 was originally published in the 2nd edition, August 2001 Pub No FHWA-NHI-01-021FHWA, and AASHTO’s Model Drainage Manual, 1991. This section presents an overview of the HEC-22 methodology used by Bentley FlowMaster. For more information, refer to “Pavement Drainage” on page 6-185 or the HEC-22 documentation.

5.7.2

Flows in Gutters on Grade Flows in gutters on grade includes: •

“Uniform Gutter Cross Slope” on page 5-166

•

“Composite Gutter Section” on page 5-168

Uniform Gutter Cross Slope In the case of a uniform cross-slope (gutter slope Sw equal to pavement slope Sx), the relationship between the gutter flow Q and the flow spread T is obtained by applying the Manning’s equation, assuming normal flow:

Q=

5-166

K c 1.67 0.5 2.67 Sx SL T n

(5.51)



Where

Q

=

Flow rate (m3/sec., ft3/sec.)

Kc

=

0.376 SI, 0.56 U.S. customary

n

=


Sx

=

Pavement cross-slope (m/m, ft/ft)

SL

=

Longitudinal pavement slope (m/m, ft/ft)

T

=

Width of flow—spread (m, ft)

T Wg

Ts

Qs Qw

Sx

Sw

Figure 5-14: Uniform Gutter Cross Slope The flow depth along the curb is: d = TSx Where

(5.52) d

=

Depth of flow at curb (m, ft)

The coefficient E, as well as the variables Qw and Qs, are introduced as: Qw = E0Q

(5.53)

Qs = Q – Qw = (1 – E0)Q

(5.54)

E0 = 1 – (1 – Wg/T)2.67

(5.55)


5-167

Inlet Hydraulics

Where

Q

=

Total pavement flow (m3/sec., ft3/sec.)

Qw

=

Frontal flow—portion of the flow over the grate width (m3/sec., ft3/sec.)

E0

=

Ratio of flow above the grate to total flow

Qs

=

Side flow—flow outside the grate width (m3/sec., ft3/sec.)

Wg

=

Grate width (m, ft)

Composite Gutter Section T W

Ts

Qs Qw

Sx

Sw a

Figure 5-15: Composite Gutter Section In the case of a composite gutter section, the coefficient E0, as well as the variables Qw and Qs, are defined as:

5-168

Qw = E0Q

(5.56)

Qs = Q – Qw = (1 – E0)Q

(5.57)



Where

Q

=

Total pavement flow (m3/sec., ft3/sec.)

Qw

=

Frontal flow—portion of the flow in the depressed gutter (m3/sec., ft3/sec.)

E0

=

Ratio of flow in the depressed gutter to total flow

Qs

=

Side flow—flow outside the depressed gutter (m3/ sec., ft3/sec.)

E0 can then be derived from Manning’s equation as:

S E0 = 1 / 1 + w Sx

Where

2.67 ø- 1 Ø Sw S x œ Œ - 1œ Œ1 + œ ŒŁ (T W )- 1ł ß º

Sw

=

Gutter cross-slope (m/m, ft/ft)

W

=

Width of depressed gutter—or grate, if it is smaller (m, ft)

(5.58)

The continuously depressed gutter is also sometimes defined by a gutter depression, a, defined as:

Sw = S x +

a 1000W SI Units

(5.59)

Sw = S x +

a 12W U.S. Customary Units

(5.60)

Where

a

=

Gutter depression (mm, in)

Gutter depression is the depression of the gutter relative to the street cross-slope projection. It is also identified as a continuously depressed gutter because the gutter is depressed along its full length.


5-169

Inlet Hydraulics

5.7.3

Flow in Ditch or Median Section on Grade T

1

1 d

Z1

Z2

W B

Figure 5-16: Ditch Cross Section The discharge Q in a ditch or median section is expressed as: 1.67 Ø z1 + z2 2 ø K c ŒBd + d œ S L0.5 œ Œ 2 ß º Q= Ø ø n ŒB + d 1 + z12 + 1 + z22 œ Œ œ º ß

(

Where

)

(5.61)

Q

=

Discharge rate (m3/sec., ft3/sec.)

Kc

=


n

=


B

=

Ditch width (m, ft)

d

=

Water depth (m, ft)

z1, z2

=

Ratio H:V for ditch side slopes (m/m, ft/ft)

SL

=

Ditch longitudinal slope (m/m, ft/ft)

The ratio E0 of frontal flow (over the grate) to total flow is:

E0 =

Where

5-170

W z + z2 B+ d 1 Ł 2 ł W

=

(5.62) Grate width (m, ft)



5.7.4

Inlet Analysis Inlets are divided into 4 categories, as illustrated in the following figure:

L h

L

W

a. Grate Inlet

W

b. Curb Opening Inlet

L h

W

c. Combination Inlet

d. Slotted Drain Inlet

Figure 5-17: Inlet Types For details on each type of inlet, refer to the HEC-22 Manual, Chapter 4 (see “Pavement Drainage” on page 6-185).


5-171

Inlet Hydraulics Note:

Do not confuse gutter depression and local depression: The gutter depression is the depression of the gutter relative to the pavement normal cross-slope named a on the figure below, which shows a gutter and inlet cross section. It is also referred to as a continuously depressed gutter. The local depression is the depression at the location of the inlet (a’ in the figure below). It does not exist in the gutter upstream or downstream of the inlet. It is measured from the gutter slope.

Sx

Q total

Q Sw Q'

S'w

Figure 5-18: Continuous Gutter Depression and Local Depression Figure 6.6 illustrates the concept of local depression versus gutter depression used by HEC-22, with: atotal = a + a' Where

(5.63)

a

=


a'

=

Local depression (mm, in)

atotal

=

Total depression at location of inlet (mm, in)

Inlets on Grade Inlets located on a grade (SL > 0) are characterized by an efficiency, E, for a given set of conditions:

E=

5-172

Qi Q

(5.64)



Where

E

=

Inlet efficiency (unitless)

Q

=

Total gutter flow (m3/sec., ft3/sec.)

Qi

=

Intercepted flow (m3/sec., ft3/sec.)

The flow that is not intercepted is called carryover or bypass flow. It is defined as follows: Qb = Q – Qi Where

5.7.5

Qb

(5.65) =

Bypass low (m3/sec., ft3/sec.)

Grate Inlet on Grade

W

L

Figure 5-19: Grate Inlet As previously defined, the total gutter flow, Q, is composed of a frontal flow Qw and a side flow Qs. The ratio Rf of frontal flow intercepted to total frontal flow is expressed as: Rf = 1 – Kcf (V – V0) Where

(5.66)

Kcf

=


V

=

Average velocity in gutter (m/sec., ft/sec.)

V0

=

Gutter velocity at which splash-over first happens (m/sec., ft/sec.)


5-173

Inlet Hydraulics Note:

If V < V0, then Rf = 1 (all the frontal flow is intercepted). Also, Rf cannot exceed 1.0. The splash-over velocity, V0 is a function of the grate type and the grate length, L.

The frontal flow intercepted, Qwi, is: Qwi = RfQw The ratio Rs of side flow intercepted to side flow is expressed as:

K V 1.8 Rs = 1 / 1 + cs 2.3 Sx L ł Ł

Where

(5.67)

Kcs

=


L

=

Grate length (m, ft)

The side flow intercepted, Qsi, is therefore: Qsi = RsQs

(5.68)

The total flow intercepted is: Qi = Qwi + Qsi Where

Qi

(5.69) =

Total flow intercepted (m3/sec., ft3/sec.)

The bypass flow is then: Qb = Q – Qi Where

Qb

(5.70) =

Bypass flow (m3/sec., ft3/sec.)

The efficiency of the grate is expressed as: E = RfE0 + Rs(1 – E0)

5-174

(5.71)


Bentley FlowMaster Theory Or, E = Qi /Q

5.7.6

(5.72)

Curb Inlet on Grade L h

W

Figure 5-20: Curb Inlet The curb opening length Lr that would be required to intercept 100% of a flow Q on a pavement with a uniform cross slope is computed as: 0.6

LT = K C Q

Where

0.42

S L0.3

1 ŁnS x ł

(5.73)

LT

=

Curb opening length required to intercept 100% of gutter flow

Kc

=


In order to account for a locally or continually depressed gutter, an equivalent cross slope, Se, is computed.

Sx Q total

Sw S'w

Figure 5-21: Composite Gutter Section


5-175

Inlet Hydraulics S'w is calculated as:

S ’w =

atotal 1000W SI Units

(5.74)

S ’w =

atotal 12W U.S. Customary Units

(5.75)

Where

S'w

=

Gutter cross-slope at inlet location—measured from pavement cross-slope (m/m, ft/ft)

Sw

=

Gutter cross-slope upstream of inlet—does not account for local depression (m/m, ft/ft)

atotal

=

Total depression at inlet location—includes local and continuous gutter depression (mm, in)

W

=

Larger of the gutter width and local-depression width (m, ft)

The curb opening length LT that would be required to intercept 100% of a flow Q on a pavement with a composite cross slope at the location of the inlet is: 0.6

LT = KT Q

0.42

S L0.3

1 ŁnSe ł

(5.76)

The efficiency E of a curb opening shorter than the required length for total interception is: 1.8

L E = 1- 1Ł LT ł

Where

5-176

L

(5.77) =

Curb opening length (m, ft)



5.7.7

Slot Inlet on Grade

Figure 5-22: Slot Inlet The efficiency of a Slotted Inlet on Grade with an opening width greater than or equal to 45 mm (1.75 in) is calculated using the same equations as for a curb opening inlet of the same length.

5.7.8

Combination Inlet on Grade L h

W

Figure 5-23: Combination Inlet HEC-22 distinguishes two cases: •

The grate and the curb opening are placed side by side. In this case, the flow interception by the curb opening is negligible, and the capacity of the combination inlet is identical to that of the grate alone.

•

The curb opening is extended upstream of the grate in order to intercept debris that could otherwise clog the grate inlet. The flow intercepted by the combination inlet is calculated as the flow intercepted by the curb opening upstream of the grate inlet, plus the portion of the remaining flow intercepted by the grate.


5-177

Inlet Hydraulics

Inlets in Sag Note:

Inlets in sag location operate as weirs at low water depth and as orifices at higher depth. Grate inlets alone are not recommended, as clogging of the grate is likely to occur.

In contrast with inlets on grade, the efficiency of an inlet located in sag is always assumed to be 1.0 (or 100%).

5.7.9

Grate Inlet in Sag

W

L

Figure 5-24: Grate Inlet The flow Qw intercepted by a grate inlet operating as a weir is:

Qw = Cw 2Wd11.5 + Cw Ld 21.5 Where

(5.78)

W

=

Width of the grate (m, ft)

L

=

Length of the grate (m, ft)

CW

=

Weir Coefficient (1.66 SI, 3.0 U.S. customary)

d1

=

Flow depth at middle of grate(m, ft)

d2

=

Flow depth at side of grate opposite the curb (m, ft)

The flow Qio intercepted by a grate inlet operating as an orifice is: Q =0.67AgP(2gd)1/2

5-178

(5.79)



Where

Q

=

Capacity of the grate operating as an orifice (cfs, m3/s)

A

=

Clear opening area of grate (ft2, m2)

d

=

Average depth of flow over grate (ft, m)

g

=

Acceleration due to gravity (ft/s2, m/s2)

The intercepted flow Qi is conservatively calculated at any flow depth by using the lesser of the intercepted flows computed using the weir or orifice equation:

Qi = min(Qiw , Qio )

(5.80)

This accounts for the three stages: weir flow, orifice flow and transitional flow.

5.7.10

Curb Inlet in Sag

L h

W

Figure 5-25: Curb Inlet Curb inlets are divided into 3 categories, based on their throat geometry: horizontal (most common), vertical, and inclined, as defined in the figure below.


5-179

Inlet Hydraulics

h

di

do

do

do = di

d o = d i -(h/2) h a. Horizontal Throat

c. Vertical Throat

0

do

h d o = d i -(h/2)Sin 0 b. Inclined Throat

Figure 5-26: Curb Inlet Throat Types

Where

h

=

Height of curb-opening inlet (m, ft)

di

=

Water depth at lip of curb (m, ft)

do

=

Effective head, measured from center of orifice throat (m, ft)

Θ

=

Throat angle for inclined-throat inlets

Weir Flow A curb inlet in a sag, without a locally or continuously depressed gutter, operates as a weir for depths at curb (measured from the normal cross slope) that are less than or equal to the curb opening height. This condition can be expressed as: d≤h Where

(5.81) d

=

Depth at curb—i.e., d = TSx (m, ft)

In the case of a depressed curb opening (local depression) or a continuously depressed gutter, the previous condition becomes:

5-180



d+

atotal £h 1000 U.S. Customary SI Units

Where

(5.82)

d

=

Total depression, measured at inlet (mm, in)

D

=

Depth at curb, measured from normal cross-slope (m, ft)

The intercepted flow Qiw by a curb-opening inlet operating as a weir, with a locally or continuously depressed gutter, is: Qiw = Cw1(L + 1.8W)d1.5 Where

(5.83)

Cw1

=

Weir coefficient (1.25 SI, 2.3 U.S. customary)

L

=

Curb-opening length (m, ft)

W

=

Lateral width of depression (m, ft)

However, if L is greater than or equal to 3.6 m (12 ft), then the following equation is used, which is the same as the equation for curb-opening inlets without depression: Qiw = Cw2Ld1.5 Where

Cw2

(5.84) =

Weir coefficient (1.6 SI, 3.0 U.S. customary)

Orifice Flow A curb inlet in a sump operates as an orifice for depths at the lip of a curb opening that are greater than 1.4 times the curb opening height: di ≥ 1.4h

(5.85)

The intercepted flow Qio by a curb-opening inlet (depressed or undepressed) operating as an orifice is: Qio = CohL(2gdo)0.5

(5.86)

which is also expressed as:


5-181

Inlet Hydraulics

ø0.5 Ø h Qio = Co hL Œ2 g di - sin Q œ Œ łœ 2 ß º Ł Where

Θ

=

(5.87)

90° for horizontal-throat inlets, 0° for verticalthroat inlets

Transition Flow At depths between 1.0 and 1.4 times the opening height, the flow is in a transition stage. This intercepted flow Qi is calculated conservatively in this depth range as: Qi = min(Qiw, Qio)

5.7.11

(5.88)

Slot Inlet in Sag Slot inlet in sag includes: •

“Weir Flow” on page 5-180

•

“Orifice Flow” on page 5-183

•

“Transitional Flow” on page 5-183

Weir Flow Slotted inlets located in sag operate as weirs to water depths, d (measured at the curb from the normal cross slope), of about 0.06 m (0.2ft). The intercepted flow Qiw is expressed as: Qiw = CwLd1.5 Where

5-182

(5.89)

Cw

=

Weir coefficient—varies with flow depth and slot length (typically 1.4 SI, 2.48 U.S. customary)

d

=

Water depth at curb, measured from normal cross slope (m, ft)

L

=

Slot length (m, ft)



Orifice Flow At water depths (measured at the curb) greater than about 0.12 m (0.4 ft), slotted inlets perform as orifices. The intercepted flow Qio is expressed as: Qio = 0.8LW(2gd)0.5 Where

(5.90)

W

=

Slot width (m, ft)

d

=

Water depth at slot (m, ft)

Transitional Flow At depths between 0.06 m (measured at the slot from the normal cross slope) and 0.12 m, the flow is in a transition stage. The intercepted flow Qi is conservatively calculated in this depth range as: Qi = min(Qiw, Qio)

5.7.12

(5.91)

Combination Inlet in Sag According to HEC-22, combination inlets are considered advisable for use in sags where hazardous ponding occurs.

Equal Length Inlets Equal length inlets refer to a grate inlet placed along the side of a curb-opening inlet of identical length. At lower flow depths, the grate inlet is operating as a weir and the interception capacity of the curb is negligible (unless the grate is clogged, in which case the curb is intercepting some flow). The flow Qiw intercepted by the combination is then: Qiw = CwPd1.5 Where

(5.92)

Cw

=

Weir coefficient (typically 1.66 SI, 3.0 U.S. customary)

P

=

Perimeter of grate, disregarding side along curb (m, ft)

d

=

Flow depth at curb (m, ft)


5-183

Inlet Hydraulics At higher flow depths, both the grate inlet and the curb-opening inlet are operating as orifices. Note:

The clear opening area of the grate depends on the opening ratio of the grate (HEC-22 defines an opening ratio for each grate type), as well as the clogging factor you specify.

The flow Qio intercepted by the combination inlet operating as an orifice is: Qio = CoAg(2gd)0.5 + CohL(2gdo)0.5 Where

(5.93)

Co

=

Orifice coefficient (Co = 0.67)

Ag

=

Clear opening of grate (m2, ft2 )

g

=

Gravitational acceleration (9.81 m/sec.2, 32.16 ft/ sec.2 )

h

=


do

=

Head, measured from the center of the orifice throat (m, ft)

Sweeper Inlet A sweeper inlet refers to a grate inlet placed at the downstream end of a longer curb opening inlet. A sweeper inlet is more efficient than an equal length combination inlet in intercepting debris. Note that since the HEC-22 manual is not very explicit about this type of inlet in sag, some assumptions were made in order to define the flows for this inlet. The flow Qi intercepted by a sweeper inlet is the sum of the flow Qie as calculated above for an equal length combination inlet of length L (where L is the length of the grate) and the flow Qic intercepted by the additional length L (upsteam of the grate) of the curb opening. Qi = Qie + Qic

5-184

(5.94)


Chapter

6

Pavement Drainage

Note:

This section was extracted from the Urban Drainage Design Manual, Hydraulic Engineering Circular Number 22 (HEC-22), Pavement Drainage; published by the Federal Highway Administration in November 1996. All charts referred to in this section are provided in “HEC 22 Charts” on page 7-279. The HEC22 methodology is used by Bentley FlowMaster to perform flow computations through inlets. Bentley FlowMaster performs hydraulic computations for analyzing or sizing one inlet at a time. For analyzing or designing an entire storm sewer network, Bentley Systems offers StormCAD, which also follows the HEC-22 methodology for inlet computations.

Effective drainage of highway pavements is essential to the maintenance of highway service level and to traffic safety. Water on the pavement can interrupt traffic, reduce skid resistance, increase potential for hydroplaning, limit visibility due to splash and spray, and cause difficulty in steering a vehicle when the front wheels encounter puddles. Pavement drainage requires consideration of surface drainage, gutter flow, and inlet capacity. The design of these elements is dependent on storm frequency and the allowable spread of storm water on the pavement surface. This section presents design guidance for the design of these elements. Most of the information presented here was originally published in HEC-12, Drainage of Highway Pavements, and AASHTO’s Model Drainage Manual.


6-185

Design Frequency and Spread

6.1

Design Frequency and Spread Two of the more significant variables considered in the design of highway pavement drainage are the frequency of the design runoff event and the allowable spread of water on the pavement. A related consideration is the use of an event of lesser frequency to check the drainage design. Spread and design frequency are not independent. The implications of the use of a criterion for spread of one-half of a traffic lane are considerably different for one design frequency than for a lesser frequency. It also has different implications for a low-traffic, low-speed highway than for a higher classification highway. These subjects are central to the issue of highway pavement drainage and important to highway safety.

6.1.1

Selection of Design Frequency and Design Spread The objective of highway storm drainage design is to provide for safe passage of vehicles during the design storm event. The design of a drainage system for a curbed highway pavement section is to collect runoff in the gutter and convey it to pavement inlets in a manner that provides reasonable safety for traffic and pedestrians at a reasonable cost. As spread from the curb increases, the risks of traffic accidents and delays, and the nuisance and possible hazard to pedestrian traffic increase. The process of selecting the recurrence interval and spread for design involves decisions regarding acceptable risks of accidents and traffic delays and acceptable costs for the drainage system. Risks associated with water on traffic lanes are greater with high traffic volumes, high speeds, and higher highway classifications than with lower volumes, speeds, and highway classifications. A summary of the major considerations that enter into the selection of design frequency and design spread follows: 1. The classification of the highway is a good starting point in the selection process since it defines the public’s expectations regarding water on the pavement surface. Ponding on traffic lanes of high-speed, high-volume highways is contrary to the public’s expectations and thus the risks of accidents and the costs of traffic delays are high. 2. Design speed is important to the selection of design criteria. At speeds greater than 70 km/hr (44 mi/hr), it has been shown that water on the pavement can cause hydroplaning. 3. Projected traffic volumes are an indicator of the economic importance of keeping the highway open to traffic. The costs of traffic delays and accidents increase with increasing traffic volumes.

6-186


Pavement Drainage 4. The intensity of rainfall events may significantly affect the selection of design frequency and spread. Risks associated with the spread of water on pavements may be less in arid areas subject to high intensity thunderstorm events than in areas accustomed to frequent but less intense events. 5. Capital costs are neither the least nor last consideration. Cost considerations make it necessary to formulate a rational approach to the selection of design criteria. Tradeoffs between desirable and practicable criteria are sometimes necessary because of costs. In particular, the costs and feasibility of providing for a given design frequency and spread may vary significantly between projects. In some cases, it may be practicable to significantly upgrade the drainage design and reduce risks at moderate costs. In other instances, such as where extensive outfalls or pumping stations are required, costs may be very sensitive to the criteria selected for use in design. Other considerations include inconvenience, hazards, and nuisances to pedestrian traffic. These considerations should not be minimized and, in some locations such as in commercial areas, may assume major importance. Local design practice may also be a major consideration since it can affect the feasibility of designing to higher standards, and it influences the public’s perception of acceptable practice. The relative elevation of the highway and surrounding terrain is an additional consideration where water can be drained only through a storm drainage system, as in underpasses and depressed sections. The potential for ponding to hazardous depths should be considered in selecting the frequency and spread criteria and in checking the design against storm runoff events of lesser frequency than the design event. Spread on traffic lanes can be tolerated to greater widths where traffic volumes and speeds are low. Spreads of one-half of a traffic lane or more are usually considered a minimum type design for low-volume local roads. The selection of design criteria for intermediate types of facilities may be the most difficult. For example, some arterials with relatively high traffic volumes and speeds may not have shoulders which will convey the design runoff without encroaching on the traffic lanes. In these instances, an assessment of the relative risks and costs of various design spreads may be helpful in selecting appropriate design criteria. Table 61 provides suggested minimum design frequencies and spread based on the type of highway and traffic speed. The recommended design frequency for depressed sections and underpasses where ponded water can be removed only through the storm drainage system is a 50-year frequency event. The use of a lesser frequency event, such as a 100-year storm, to assess hazards at critical locations where water can pond to appreciable depths is commonly referred to as a check storm or check event.


6-187

Design Frequency and Spread

6.1.2

Selection of Check Storm and Spread A check storm should be used any time runoff could cause unacceptable flooding during less frequent events. Also, inlets should always be evaluated for a check storm when a series of inlets terminates at a sag vertical curve where ponding to hazardous depths could occur. The frequency selected for the check storm should be based on the same considerations used to select the design storm, i.e., the consequences of spread exceeding that chosen for design and the potential for ponding. Where no significant ponding can occur, check storms are normally unnecessary. Criteria for spread during the check event are: 1) one lane open to traffic during the check storm event, and 2) one lane free of water during the check storm event. These criteria differ substantively, but each sets a standard by which the design can be evaluated. Table 6-1: Suggested Minimum Design Frequency and Spread Road Classification

Design Frequency

Design Spread

High Volume, Divided, or Bi-Directional

<70 km/hr (45 mph)

10-year

Shoulder +1m (3ft)

>70 km/hr (45 mph)

10-year

Shoulder

Sag Point

50-year

Shoulder +1m (3ft)

<70 km/hr (45 mph

10-year

1/2 driving lane

>70 km/hr (45 mph)

10-year

Shoulder

Sag Point

10-year

1/2 driving lane

Low ADT

5-year

1/2 driving lane

High ADT

10-year

1/2 driving lane

Sag Point

10-year

1/2 driving lane

Collector

Local Streets

6-188


Pavement Drainage

6.2

Surface Drainage When rain falls on a sloped pavement surface, it forms a thin film of water that increases in thickness as it flows to the edge of the pavement. Factors which influence the depth of water on the pavement are the length of flow path, surface texture, surface slope, and rainfall intensity. As the depth of water on the pavement increases, the potential for vehicular hydroplaning increases. For the purposes of highway drainage, a discussion of hydroplaning is presented and design guidance for the following drainage elements is presented: •

longitudinal pavement slope

•

cross or transverse pavement slope

•

curb and gutter design

•

roadside and median ditches

•

bridge decks

•

median barriers

•

impact attenuators

Additional technical information on the mechanics of surface drainage can be found in Improved Surface Drainage of Pavements, published by the Federal Highway Administration in 1995.

6.2.1

Hydroplaning As the depth of water flowing over a roadway surface increases, the potential for hydroplaning increases. When a rolling tire encounters a film of water on the roadway, the water is channeled through the tire tread pattern and through the surface roughness of the pavement. Hydroplaning occurs when the drainage capacity of the tire tread pattern and the pavement surface is exceeded and the water begins to build up in front of the tire. As the water builds up, a water wedge is created and this wedge produces a hydrodynamic force which can lift the tire off the pavement surface. This is considered as full dynamic hydroplaning and, since water offers little shear resistance, the tire loses its tractive ability and the driver has a loss of control of the vehicle.


6-189

Surface Drainage Hydroplaning is a function of the water depth, roadway geometrics, vehicle speed, tread depth, tire inflation pressure, and conditions of the pavement surface. It has been shown that hydroplaning can occur at speeds of 89 km/hr (55 mph) with a water depth of 2 mm (0.08 in). The following can reduce the hydroplaning potential of a roadway surface: 1. Design the highway geometries to reduce the drainage path lengths of the water flowing over the pavement. This will prevent flow build-up. 2. Increase the pavement surface texture depth by such methods as grooving of Portland cement concrete. An increase of pavement surface texture will increase the drainage capacity at the tire pavement interface. 3. The use of open graded asphaltic pavements has been shown to greatly reduce the hydroplaning potential of the roadway surface. This reduction is due to the ability of the water to be forced through the pavement under the tire. This releases any hydrodynamic pressures that are created and reduces the potential for the tire to hydroplane. 4. The use of drainage structures along the roadway to capture the flow of water over the pavement will reduce the thickness of the film of water and reduce the hydroplaning potential of the roadway surface.

6.2.2

Longitudinal Slope Experience has shown that the recommended minimum values of roadway longitudinal slope given in the AASHTO Policy on Geometric Design will provide safe, acceptable pavement drainage. In addition, the following general guidelines are presented: 1. A minimum longitudinal gradient is more important for a curbed pavement than for an uncurbed pavement since the water is constrained by the curb. However, flat gradients on uncurbed pavements can lead to a spread problem if vegetation is allowed to build up along the pavement edge. 2. Desirable gutter grades should not be less than 0.5 percent for curbed pavements with an absolute minimum of 0.3 percent. Minimum grades can be maintained in very flat terrain by use of a rolling profile, or by warping the cross slope to achieve rolling gutter profiles. 3. To provide adequate drainage in sag vertical curves, a minimum slope of 0.3 percent should be maintained within 15 meters (50 ft) of the low point of the curve. This is accomplished where the length of the curve in meters divided by the algebraic difference in grades in percent (K) is equal to or less than 50 (167 in U.S. customary units). This is represented as:

6-190


Pavement Drainage

K=

Where

6.2.3

L G2 - G1

(6.1)

K

=

Vertical curve constant (m/%, ft/%)

L

=

Horizontal length of curve (m, ft)

Gi

=

Grade of roadway (%)

Cross (Transverse) Slope Table 6-2 indicates an acceptable range of cross slopes as specified in AASHTO’s policy on geometric design of highways and streets. These cross slopes are a compromise between the need for reasonably steep cross slopes for drainage and relatively flat cross slopes for driver comfort and safety. These cross slopes represent standard practice. As reported in Pavement and Geometric Design Criteria for Minimizing Hydroplaning, cross slopes of 2 percent have little effect on driver effort in steering or on friction demand for vehicle stability. Use of a cross slope steeper than 2 percent on pavements with a central crown line is not desirable. In areas of intense rainfall, a somewhat steeper cross slope (2.5 percent) may be used to facilitate drainage. On multi-lane highways where three (3) lanes or more are sloped in the same direction, it is desirable to counter the resulting increase in flow depth by increasing the cross slope of the outermost lanes. The two (2) lanes adjacent to the crown line should be pitched at the normal slope, and successive lane pairs, or portions thereof outward, should be increased by about 0.5 to 1 percent. The maximum pavement cross slope should be limited to 4 percent (refer to table 6-2). Additional guidelines related to cross slope are: 1. Although not widely encouraged, inside lanes can be sloped toward the median if conditions warrant. 2. Median areas should not be drained across travel lanes. 3. The number and length of flat pavement sections in cross slope transition areas should be minimized. Consideration should be given to increasing cross slopes in sag vertical curves, crest vertical curves, and in sections of flat longitudinal grades. 4. Shoulders should be sloped to drain away from the pavement, except with raised, narrow medians and super-elevations.


6-191

Surface Drainage

6.2.4

Curb and Gutter Curbs are normally used at the outside edge of pavements for low-speed, highway facilities, and in some instances adjacent to shoulders on moderate to high-speed facilities. They serve the following purposes: •

contain the surface runoff within the roadway and away from adjacent properties,

•

prevent erosion on fill slopes,

•

provide pavement delineation, and

•

enable the orderly development of property adjacent to the roadway. Table 6-2: Normal Pavement Cross Slopes Surface Type

Range in Rate of Surface Slope

2 Lanes (High-Type Surface)

0.015 – 0.020

3 or more lanes, each direction (High-Type Surface)

0.015 minimum; increase 0.005 to 0.010 per lane; 0.040 maximum

Intermediate Surface

0.015 – 0.030

Low-Type Surface

0.020 – 0.060

Bituminous or Concrete Shoulders

0.020 – 0.060

Bituminous or Concrete Shoulders With Curbs

>= 0.040

Gutters formed in combination with curbs are available in 0.3 through 1.0 meter (12 through 39 inch) widths. Gutter cross slopes may be equal to that of the pavement or may be designed with a steeper cross slope, usually 80 mm per meter (1 inch per foot) steeper than the shoulder or parking lane (if used). AASHTO geometric guidelines state that an 8% slope is a common maximum cross slope. A curb and gutter combination forms a triangular channel that can convey runoff less than or equal to the design flow without interruption of the traffic. When a design flow occurs, there is a spread or widening of the conveyed water surface. The water spreads to include not only the gutter width, but also parking lanes or shoulders, and portions of the traveled surface. Spread is what concerns the hydraulic engineer in curb and gutter flow. The distance of the spread, T, is measured perpendicular to the curb face to the extent of the water on the roadway and is shown in Figure 6-1.

6-192


Pavement Drainage Limiting this width becomes a very important design criterion and will be discussed in detail in “Flow in Gutters” on page 6-195. Where practical, runoff from cut slopes and other areas draining toward the roadway should be intercepted before it reaches the highway. By doing so, the deposition of sediment and other debris on the roadway as well as the amount of water which must be carried in the gutter section will be minimized. Where curbs are not needed for traffic control, shallow ditch sections at the edge of the roadway pavement or shoulder offer advantages over curbed sections by providing less of a hazard to traffic than a near-vertical curb and by providing hydraulic capacity that is not dependent on spread on the pavement. These ditch sections are particularly appropriate where curbs have historically been used to prevent water from eroding fill slopes.

6.2.5

Roadside and Median Channels a. Conventional Curb and Gutter Sections

y

T

y=ax-bx 2

Ts

W T Qs

Qw

d

Sx

Sx

y a

1. Uniform Section

Sw

x

2. Composite Section

H

a=2H/B b=H/B 2 x

3. Curved Section

b. Shallow Swale Sections

AB A S x1 B

T1 BC

Sx2

T

T AB BC

D

Ts

C

Sx3 D

1. "V"-Shape Gutter

Sx3

A S x1

B Sx2

Sx3

d

C

2. "V"-Shape Median

3. Circular Section

Figure 6-1: Typical Gutter Sections


6-193

Surface Drainage Roadside channels are commonly used with uncurbed roadway sections to convey runoff from the highway pavement and from areas which drain toward the highway. Due to right-of-way limitations, roadside channels cannot be used on most urban arterials. They can be used in cut sections, depressed sections, and other locations where sufficient right-of-way is available and driveways or intersections are infrequent. To prevent drainage from the median areas from running across the travel lanes, slope median areas and inside shoulders to a center swale. This design is particularly important for high speed facilities and for facilities with more than two lanes of traffic in each direction.

6.2.6

Bridge Decks Bridge deck drainage is similar to that of curbed roadway sections. Effective bridge deck drainage is important for the following reasons: •

Deck structural and reinforcing steel is susceptible to corrosion from deicing salts

•

Moisture on bridge decks freezes before surface roadways

•

Hydroplaning often occurs at shallower depths on bridges due to the reduced surface texture of concrete bridge decks

Bridge deck drainage is often less efficient than roadway sections because cross slopes are flatter, parapets collect large amounts of debris, and drainage inlets or typical bridge scuppers are less hydraulically efficient and more easily clogged by debris. Because of the difficulties in providing for and maintaining adequate deck drainage systems, gutter flow from roadways should be intercepted before it reaches a bridge. For similar reasons, zero gradients and sag vertical curves should be avoided on bridges. Additionally, runoff from bridge decks should be collected immediately after it flows onto the subsequent roadway section where larger grates and inlet structures can be used. A detailed coverage of bridge deck drainage systems is included in Design of Bridge Deck Drainage, published by the Federal Highway Administration in 1993.

6.2.7

Median Barriers Slope the shoulder areas adjacent to median barriers to the center to prevent drainage from running across the traveled pavement. Where median barriers are used, and particularly on horizontal curves with associated superelevations, it is necessary to provide inlets or slotted drains to collect the water accumulated against the barrier. Additionally, some highway department agencies use a piping system to convey water through the barrier.

6-194


Pavement Drainage

6.2.8

Impact Attenuators The location of impact attenuator systems should be reviewed to determine the need for drainage structures in these areas. With some impact attenuator systems it is necessary to have a clear or unobstructed opening as traffic approaches the point of impact to allow a vehicle to impact the system head on. If the impact attenuator is placed in an area where superelevation or other grade separation occurs, grate inlets and/or slotted drains may be needed to prevent water from running through the clear opening and crossing the highway lanes or ramp lanes. Curb, curb-type structures or swales cannot be used to direct water across this clear opening as vehicle vaulting could occur.

6.3

Flow in Gutters A pavement gutter is defined, for purposes of this circular, as a section of pavement adjacent to the roadway which conveys water during a storm runoff event. It may include a portion or all of a travel lane. Gutter sections can be categorized as conventional or shallow swale type as illustrated in Figure 6-1. Conventional curb and gutter sections usually have a triangular shape with the curb forming the near-vertical leg of the triangle. Conventional gutters may have a straight cross slope (Figure 6-1, a.1.), a composite cross slope where the gutter slope varies from the pavement cross slope (Figure 6-1, a.2.), or a parabolic section (Figure 6-1, a.3.). Shallow swale gutters typically have V-shaped or circular sections as illustrated in Figure 6-1, b.1, b.2., and b.3., respectively, and are often used in paved median areas on roadways with inverted crowns.

6.3.1

Capacity Relationship Gutter flow calculations are necessary to establish the spread of water on the shoulder, parking lane, or pavement section. A modification of the Manning equation can be used for computing flow in triangular channels. The modification is necessary because the hydraulic radius in the equation does not adequately describe the gutter cross section, particularly where the top width of the water surface may be more than 40 times the depth at the curb. To compute gutter flow, the Manning equation is integrated for an increment of width across the section. The resulting equation is:

Q=

K c 1.67 0.5 2.67 Sx SL T n


(6.2)

6-195

Flow in Gutters

Where

Kc

=


n

=

Manning’s coefficient (see Table 6-3)

Q

=

Flow rate (m3 /sec., ft3/sec.)

T

=

Width of flow—spread (m, ft)

Sx

=

Cross slope (m/m, ft/ft)

SL

=

Longitudinal slope (m/m, ft/ft)

Equation 6.2 neglects the resistance of the curb face since this resistance is negligible. Spread on the pavement and flow depth at the curb are often used as criteria for spacing pavement drainage inlets. Design Chart 1 in “HEC 22 Charts” on page 7-279 is a nomograph for solving Equation 6.2. The chart can be used for either criterion with the relationship:

d = TS x Where

d

(6.3) =

Depth of flow (m, ft)

Chart 1 can be used for direct solution of gutter flow where the Manning n value is 0.016. For other values of n, divide the value of Qn by n. Instructions for use and an example problem solution are provided on the chart. Table 6-3: Manning’s n for Street and Pavement Gutters

6-196

Type of Gutter or Pavement

Manning’s n

Concrete gutter, trowled finish

0.012

Asphalt pavement, smooth texture

0.013

Asphalt pavement, rough texture

0.016

Concrete gutter-asphalt pavement, smooth

0.013

Concrete gutter-asphalt pavement, rough

0.015


Pavement Drainage Table 6-3: Manning’s n for Street and Pavement Gutters Type of Gutter or Pavement

Manning’s n

Concrete pavement, float finish

0.014

Concrete pavement, broom finish

0.016

For gutters with small slope, where sediment may accumulate, increase the above values of “n” by 0.02 Reference: USDOT, FHWA, HDS-3

6.3.2

Conventional Curb and Gutter Sections Conventional gutters begin at the inside base of the curb and usually extend from the curb face toward the roadway centerline a distance of 0.3 to 1 meter. As illustrated in Figure 6-1, gutters can have uniform, composite, or curved sections. Uniform gutter sections have a cross-slope which is equal to the cross-slope of the shoulder or travel lane adjacent to the gutter. Gutters having composite sections are depressed in relation to the adjacent pavement slope. That is, the paved gutter has a cross-slope which is steeper than that of the adjacent pavement. This concept is illustrated in Example 6-1. Curved gutter sections are sometimes found along older city streets or highways with curved pavement sections. Procedures for computing the capacity of curb and gutter sections follow.

Conventional Gutters of Uniform Cross Slope The nomograph in Chart 1 solves Equation 6.2 for gutters having triangular cross sections. Example 6-1 illustrates its use for the analysis of conventional gutters with uniform cross slope. EXAMPLE 6-1 Given: SL = 0.0010 m/m SX = 0.020 m/m n = 0.016


6-197

Flow in Gutters Find: 1. Spread at flow of 0.05 m3/sec. (1.8 ft3/sec.) 2. Gutter flow at spread of 2.5 m (8.2 ft) Solution 1: Compute spread T, using Equation 6.2 or from Chart 1. 0.375 T= Ø Qn) (K m S 1x.67 S L0.5 )ø ( Œ œ º ß

Ø T = Œ(0.0008) º

1.67

{(0.376)(0.0020)

0.375 0.5 (0.010) }øœ

ß

T = 2.7 m (8/9 ft) Solution 2: Using Equation 6.2 or Chart 1 with T = 2.5 m, and the preceding information, determine Qn.

Qn = K m S 1x.67 S L0.5T 2.67 1.67

Qn = (0.376)(0.020)

0.5 2.67 (0.010) (2.5)

Qn = 0.00064 m3/sec. (1.4 ft3/sec.)

Composite Gutter Sections The design of composite gutter sections requires consideration of flow in the depressed segment of the gutter, Qw. Equation 6.4, displayed graphically as Chart 2, is provided for use with Equations 6.5 and 6.6 and Chart 1 to determine the flow in a width of gutter in a composite cross section, W, less than the total spread, T. The procedure for analyzing composite gutter sections is demonstrated in Example 6-2.

6-198


Pavement Drainage

Eo = 1 / 1 +

S w sx ø2.67 Ø œ Œ Œ Sw S x œ 1 -1 + Œ T œ œ Œ Œ W œ ß º

QW = Q - Qs Where

Q=

(6.5)

Qw

=

Flow rate in depressed section of gutter (m3/sec., ft3/sec.)

Q

=

Gutter flow rate (m3/sec., ft3/sec.)

Qs

=

Flow capacity of gutter section above depressed section (m3/sec., ft3/sec.)

Qs (1 - Eo )

Where

(6.4)

(6.6)

Eo

=

Ratio of flow in a chosen width (usually the width of a grate) to the total gutter flow (Qw/Q)

Sw

=

Sx+a/W (see Figure 6-1 a.2)

Figure 6-2 illustrates a design chart for a composite gutter with a 0.60 m (2 foot) wide gutter section with a 50 mm depression at the curb that begins at the projection of the uniform cross slope at the curb face. A series of charts similar to Figure 6-2 for typical gutter configurations could be developed. EXAMPLE 6-2 Given: Gutter section illustrated in Figure 6-1 a.2 with: W = 0.6 m (2 ft) SL = 0.01


6-199

Flow in Gutters Sx = 0.020 n = 0.016 Gutter depression, a = 50 mm Find: 1. Gutter flow at a spread, T, of 2.5 m (8.2 ft) 2. Spread at a flow of 0.12 m3/sec. (4.2 ft3/sec.) Solution 1: 1. Compute the cross-slope of the depressed gutter, Sw, and the width of spread from the junction of the gutter and the road to the limit of the spread, Ts. Sw = a / W + Sx Sw = [(50) / 1000] / (0.6) + (0.020) = 0.102 m/m Ts = T – W = 2.5 m – 0.6 m Ts = 1.9 m (6.2 ft) 2. From Equation 6.2 or from Chart 1 (using Ts):

Qs n = K m S 1x.67 S L0.5T 2.67 Qsn = (0.376)(0.02)1.67(0.01)0.5(1.9)2.67 Qsn = 0.00031 m3/sec. (0.011 ft3/sec.) Qs = Qs / n = 0.00031 / 0.016 Qs = 0.019 m3/sec. (0.75 ft3/sec.) 3. Determine the gutter flow, Q, using Equation 6.4 or Chart 2. T / W = 2.5 / 0.6 = 4.17 Sw / Sx = 0.103 / 0.020 = 5.15 Eo = 1 / {1+[(Sw / Sx) / (1 + (Sw / Sx) / (T / W – 1))2.67 – 1]} Eo = 1 / {1+[5.15 / (1 + (5.15) / (4.17 – 1))2.67 – 1]} Eo = 0.70 Or, from Chart 2, Eo = Qw / Q = 0.70 Q = Qw / Eo = Qs / (1 – Eo)

6-200


Pavement Drainage Q = 0.019 / (1 – 0.70) Q = 0.06 m3/sec. (2.3 ft3/sec.)

Figure 6-2: Spread Curves for a Composite Gutter Section Solution 2: 1. Try Qs – 0.04 m3/sec. (1.4 ft3/sec.) 2. Compute Qw Qw = Q – Qs = 0.12 – 0.04


6-201

Flow in Gutters Qw = Q – Qs = 0.12 – 0.04 Qw = 0.08 m3/sec. (2.8 ft3/sec.) 3. Using Equation 6.4 or from Chart 2, determine the W / T ratio. Eo = Qw / Q = 0.08 / 0.12 = 0.67 Sw / Sx = 0.103 / 0.020 = 5.15 W / T = 0.23 (from Chart 2) 4. Compute spread based on the assumed Qs. T = W / (W / T) = 0.6 / 0.23 T = 2.6 m (8.6 ft) 5. Compute Ts based on assumed Qs. Ts = T – W = 2.6 – 0.6 = 2.0 m (6.6 ft) 6. Use Equation 6.2 or Chart 1 to determine Qs for computed Ts.

Qs n = KS 1x.67 S L0.5T 2.67 Qsn = (0.376)(0.02)1.67(0.01)0.5(2.0)2.67 Qsn = 0.00035 m3/sec. (0.00123 ft3/sec.) Qs = Qsn / n = 0.00035 / 0.016 Qs = 0.022 m3/sec. (0.77 ft3/sec.) 7. Compare the computed Qs with the assumed Qs. Qs assumed = 0.04 > 0.022 = Qs computed 8. Try a new assumed Qs and repeat steps 2 through 7. Assume Qs = 0.058 m3/sec. (2.0 ft3/sec.) Qw = 0.12 – 0.058 = 0.62 m3/sec. (2.2 ft3/sec.) Eo = Qw / Q = 0.062 / 0.12 = 0.52 Sw / Sx = 5.15 W / T = 0.17 T = 0.60 / 0.17 = 3.5 m (11.5 ft) Ts = 3.5 – 0.6 = 2.9 m (9.5 ft)

6-202


Pavement Drainage Qsn = 0.00064 m3/sec. (0.032 ft3/sec.) Qs = 0.00094 / 0.016 = 0.059 m3/sec. (2.1 ft3/sec.) Qs assumed = 0.058 m3/sec. equal to 0.059 m3/sec. = Qs computed

Conventional Gutters with Curved Sections Where the pavement cross section is curved, gutter capacity varies with the configuration of the pavement. For this reason, discharge-spread or discharge-depth at-the-curb relationships developed for one pavement configuration are not applicable to another section with a different crown height or half-width.

6.3.3

Shallow Swale Sections Where curbs are not needed for traffic control, a small swale section of circular or V shape may be used to convey runoff from the pavement. As an example, the control of pavement runoff on fills may be needed to protect the embankment from erosion. Small swale sections may have sufficient capacity to convey the flow to a location suitable for interception.

V-Sections Chart 1 can be used to compute the flow in a shallow V-shaped section. When using Chart 1 for V-shaped channels, the cross slope, Sx is determined by the following equation:

Sx =

S x1 S x 2 (S x1 + S x 2 )

(6.7)

Example 6-3 demonstrates the use of Chart 1 to analyze a V-shaped shoulder gutter. Analysis of a V-shaped gutter resulting from a roadway with an inverted crown section is illustrated in Example 6-4. EXAMPLE 6-3 Given: A V-shaped roadside gutter (Figure 6-1 a.1) with: SL = 0.01 n = 0.016 Sx1 = 0.25 Sx2 = 0.04


6-203

Flow in Gutters Sx3 = 0.02 Distance BC = 0.6 m (2.0 ft) Find: 1. Spread at a flow of 0.05 m3/sec. (1.8 ft3/sec.) 2. Flow at a spread of 1.8 m (5.9 ft) Solution 1: 1. Calculate Sx. Sx = Sx1Sx2 / (Sx1 + Sx2) = (0.25)(0.04) / (0.25 + 0.04) Sx = 0.0345 2. Using Equation 6.2 or Chart 1: 0.375 1.67 0.5 ø T ’= Ø Qn KS S ( ) ( ) x L Œ œ º ß

T' = [(0.05)(0.016) / {(0.376)(0.0345)1.67(0.01)0.5}]0.375 T' = 1.94 m (6.4 ft) T' is the hypothetical spread that is correct if it is contained within Sx1 and Sx2.) 3. To determine if T' is within Sx1 and Sx2, compute the flow depth, dB, at point B, and use this depth to find the horizontal distance between points A and B, AB. dB can be computed using the following geometric relationship: T' = (dB / Sx1) + (dB / Sx2), from which dB = T'(Sx1)(Sx2) / (Sx1 + Sx2) = (1.94)(0.25)(0.04) / (0.25 + 0.04) dB = 0.067 m (0.22 ft) AB = dB / Sx1 = 0.067 / 0.25 AB = 0.27 m (0.9 ft) AC = AB + 0.6 m = 0.27 m + 0.6 m. AC = 0.87 m (2.9 ft) 0.87 m < T' therefore, spread falls outside the V-shaped gutter section 4. Solve for the depth at point C, dC, and compute the actual spread from the edge of gutter section Ts. dC = dB – BC(Sx2) = (0.067) – (0.60)(0.04)

6-204


Pavement Drainage dC = 0.043 m (0.14 ft) Therefore, Ts = dC / Sx3 = (0.043) / (0.02) Ts = 2.15 m (7.1 ft) Solution 2: 1. Compute the depth at point C, dC. dC = (Ts)(Sx3) = (1.80 m)(0.02) dC = 0.036 m (0.12 ft) 2. Compute dB. dB = [(BC)(Sx2)] + dC dB = [(0.60 m)(0.04)] + 0.036 m dB = 0.06 m (0.2 ft) 3. Compute T'. T' = dB / Sx1 + BC + dC / Sx2 T' = (0.06 / 0.25) + 0.6 + (0.036 / 0.04) T' = 1.74 m (5.7 ft) 4. Using Equation 6.2 or Chart 1, compute Q. Sx = (0.25)(0.04) / (0.25 + 0.04) Sx = 0.034

Q = KS 1x.67 S L0.5T 2.67 n Q = (0.376)(0.034)1.67(0.01)0.5(1.74)2.67 / (0.016) Q = 0.04 m3/sec. (1.3 ft3/sec.)


6-205

Flow in Gutters EXAMPLE 6-4

Given: V-shaped gutter as illustrated in Figure 6.1 b.22 with AB = 3 m (9.8 ft) BC (9.8 ft ) S L = 0.01 n = 0.016 S x1 = S x 2 = 0.04 S x 3 = 0.02 Find: (1) Spread at a flow of 0.05 m3 /s (1.8 cfs) (2) Flow at a spread of 3 m (9.8 ft) Solution (1) Step 1. Compute Sx S x = (S x1 S x 2 ) (S x1 + S x 2 )= (0.04)(0.04) (0.04 + 0.04) S x = 0.02 Step 2. From Equation 6.2 or Chart 1 0.375 T= Ø Qn) (KS 1x.67 S L0.5 )ø ( Œ œ º ß 0.375 1.67 0.5 ø Ø T = Œ(0.05)(0.016) (0.376)(0.02) (0.01) œ º ß T = 2.7 m (9.0 ft) This is within Sx1 and Sx2 , therefore OK

{

}

Soution (2): Step 1. Compute Sx From Part 1, Step 1 above, Sx = 0.02

Step 2. From Equation 6.2 or Chart 1 67 0.5 2.67 n Q = KS 1.6 x SL T 1.67

Q = (0.376)(0.02)

0.5

2.67

(0.01) (3)

(0.016)

3

Q = 0.064 m /s(2.3cfs)

Circular Sections Flow in shallow circular gutter sections can be represented by the relationship:

6-206


Pavement Drainage

Ø Qn ø0.488 d œ = KC Œ ŒD 2.67 S 0.5 œ D Œ L œ ß º Where

(6.8)

d

=

Depth of flow in circular gutter (m, ft)

D

=

Diameter of circular gutter (m, ft)

Kc

=


which is displayed on Chart 3. The chord of the arc which can be computed using Equation 6.9 represents the width of circular gutter section Tw. 2 0.5

Tw = 2 r 2 - (r - d )

(

Where

)

(6.9)

Tw

=

Width of circular gutter section (m, ft)

r

=

Radius of flow in circular gutter (m, ft)


6-207

Flow in Gutters EXAMPLE 6-5

Given: A circular gutter swale as illustrated in Figuree 6.1b (3) with a 1.5 meter (4.9 ft) diameter and S L = 0.01 n = 0.016 Q = 0.5 m3 /s (17.6 cfs) Find: Flow Depth and top width Solution: Step 1. Determine th he value of 2.67 0.5 Qn (D 2.67 S L0.5 )= (0.5)(0.016) Ø (1.5) (0.01) øœ Œ º ß = 0.027 Step 2. Using Equation 6.8 or Chart 3, determine d D 0.488 0.488 2.67 0.5 ø d D = KD Ø Qn D S ( ) ( ) L Œ œ = (1.179)[0.027 ] º ß d D = 0.20

d = D (d D )= 1.5 (0.20)= 0.30m(0.98 ft ) Step 3. Using Equation 6.9, determine Tw 12 2ø 2 Ø(0.75)2 - (0.75 - 0.3)2 ø1 2 = 2 Tw = 2 Ø r r d ( ) Œ œ Œ œ º ß º ß = 1.2 m (3.9 ft)

6.3.4

Flow in Sag Vertical Curves As gutter flow approaches the low point in a sag vertical curve the flow can exceed the allowable design spread values as a result of the continually decreasing gutter slope. The spread in these areas should be checked to insure it remains within allowable limits. If the computed spread exceeds design values, additional inlets should be provided to reduce the flow as it approaches the low point. Sag vertical curves and measures for reducing spread are discussed further in “Drainage Inlet Design” on page 6-212.

6-208


Pavement Drainage

6.3.5

Relative Flow Capacities Example 6-1 and Example 6-2 illustrate the advantage of a composite gutter section. The capacity of the section with a depressed gutter in the examples is 70 percent greater than that of the section with a straight cross slope with all other parameters held constant. Equation (6.2) can be used to examine the relative effects of changing the values of spread, cross slope, and longitudinal slope on the capacity of a section with a straight cross slope. To examine the effects of cross slope on gutter capacity, Equation (6.2) can be transformed as follows into a relationship between Sx and Q as follows: Let

K1 =

n K m S L0.5T 2.67

(6.10)

Then

S 1x.67 = K1Q

(6.11)

And 1.67

S x1 ŁS x 2 ł

K1Q1 Q = 1 K1Q2 Q2

=

(6.12)

Similar transformations can be performed to evaluate the effects of changing longitudinal slope and width of spread on gutter capacity resulting in Equations 6.13 and 6.14 respectively. 0.5

S L1 Q = 1 Q2 ŁS L 2 ł 2.67

T1 ŁT2 ł

=

Q1 Q2


(6.13)

(6.14)

6-209

Flow in Gutters Equations 6.10, 6.13, and 6.14 are illustrated in Figure 6-3. As illustrated, the effects of spread on gutter capacity are greater than the effects of cross slope and longitudinal slope, as would be expected due to the larger exponent of the spread term. The magnitude of the effect is demonstrated when gutter capacity with a 3 meter (9.8 ft) spread is 18.8 times greater than with a 1 meter (3.3 ft) spread, and 3 times greater than a spread of 2 meters (6.6 ft). The effects of cross slope are also relatively great as illustrated by a comparison of gutter capacities with different cross slopes. At a cross slope of 4 percent, a gutter has 10 times the capacity of a gutter of 1 percent cross slope. A gutter at 4 percent cross slope has 3.2 times the capacity of a gutter at 2 percent cross slope.

Figure 6-3: Relative Effects of Spread, Cross Slope, and Longitudinal Slope on Gutter Capacity

6-210


Pavement Drainage Little latitude is generally available to vary longitudinal slope in order to increase gutter capacity, but slope changes which change gutter capacity are frequent. Figure 63 shows that a change from S = 0.04 to 0.02 will reduce gutter capacity to 71 percent of the capacity at S = 0.04. Table 6-4: Spread at Average Velocity in a Reach of Triangular Gutter

6.3.6

T1/T2

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Ta/T2

0.66

0.68

0.70

0.74

0.77

0.82

0.86

0.90

Gutter Flow Time The flow time in gutters is an important component of the time of concentration for the contributing drainage area to an inlet. To find the gutter flow component of the time of concentration, a method for estimating the average velocity in a reach of gutter is needed. The velocity in a gutter varies with the flow rate and the flow rate varies with the distance along the gutter, i.e., both the velocity and flow rate in a gutter are spatially varied. The time of flow can be estimated by use of an average velocity obtained by integration of the Manning equation for the gutter section with respect to time. Table 6-4 and Chart 4 can be used to determine the average velocity in triangular gutter sections. In the table, T1 and T2 are the spread at the upstream and downstream ends of the gutter section respectively. Ta is the spread at the average velocity. Chart 4 is a nomograph to solve equation 6.15 for the velocity in a triangular channel with known cross slope, gutter slope, and spread.

V=

Where

K C 0.5 0.67 0.67 SL Sx T n

(6.15)

Kc

=


V

=

Velocity in the triangular channel (m/sec., ft/sec.)

Example 6-6 illustrates the use of Table 6-4 and Chart 4 to determine the average gutter velocity.


6-211

Drainage Inlet Design EXAMPLE 6-6

Given: A triangular gutter section with the following characteristics: T1 = 1 m (3.3 ft) T2 = 3 m (9.8 ft) S L = 0.03 S x = 0.02 n = 0.016 Inlet spacing anticipated to be 100 meters (330 ft) Find: Time of flow in gutter Solution: wnstream spread ratio Step 1. Compute the upstream to dow T1 T2 = 1 3 = 0.33 Step 2. Determine the spread at average velocity interpolating between values in Table 6-4.

(0.30 - 0.33) (0.3 - 0.4)= X (0.74 - 0.70) X = 0.01 Ta T2 = 0.70 + 0.01 = 0.71 Ta = (0.71)(3)= 2.13 m (7.0 ft) Step 3. Using Equation 6.15 or Chart 4, determine the aveerage velocity Va = 0.752 / nS L0.5 S x0.67 T 0.67 0.5

Va = (0.752) (0.016)(0.03)

0.67

0.67

(0.02) (2.13)

Va = 0.98 m/s (3.2 ft/s) Step 4. Compute the travel time in the gutter. t = (100)/ (0.98)/ 60 = 1.7 minutes

6.4

Drainage Inlet Design The hydraulic capacity of a storm drain inlet depends upon its geometry as well as the characteristics of the gutter flow. Inlet capacity governs both the rate of water removal from the gutter and the amount of water that can enter the storm drainage system. Inadequate inlet capacity or poor inlet location may cause flooding on the roadway resulting in a hazard to the traveling public.

6-212


Pavement Drainage

6.4.1

Inlet Types Storm drain inlets are used to collect runoff and discharge it to an underground storm drainage system. Inlets are typically located in gutter sections, paved medians, and roadside and median ditches. Inlets used for the drainage of highway surfaces can be divided into the following four classes: •

Grate inlets

•

Curb-opening inlets

•

Slotted inlets

•

Combination inlets

Grate inlets consist of an opening in the gutter or ditch covered by a grate. Curb opening inlets are vertical openings in the curb covered by a top slab. Slotted inlets consist of a pipe cut along the longitudinal axis with bars perpendicular to the opening to maintain the slotted opening. Combination inlets consist of both a curb opening inlet and a grate inlet placed in a side-by-side configuration, but the curb opening may be located in part upstream of the grate. Figure 6-4 illustrates each class of inlets. Slotted drains may also be used with grates and each type of inlet may be installed with or without a depression of the gutter.

6.4.2

Characteristics and Uses of Inlets Grate inlets, as a class, perform satisfactorily over a wide range of gutter grades. Grate inlets generally lose capacity with increase in grade, but to a lesser degree than curb opening inlets. The principal advantage of grate inlets is that they are installed along the roadway where the water is flowing. Their principal disadvantage is that floating trash or debris may clog them. For safety reasons, preference should be given to grate inlets where out-of-control vehicles might be involved. Additionally, where bicycle traffic occurs, grates should be bicycle safe. Curb-opening inlets are most effective on flatter slopes, in sags, and with flows which typically carry significant amounts of floating debris. The interception capacity of curb-opening inlets decreases as the gutter grade steepens. Consequently, the use of curb-opening inlets is recommended in sags and on grades less than 3%. Of course, they are bicycle safe as well. Combination inlets provide the advantages of both curb opening and grate inlets. This combination results in a high capacity inlet which offers the advantages of both grate and curb-opening inlets. When the curb opening precedes the grate in a Sweeper configuration, the curb-opening inlet acts as a trash interceptor during the initial phases of a storm. Used in a sag configuration, the sweeper inlet can have a curb opening on both sides of the grate.


6-213

Drainage Inlet Design Slotted inlets can be used in areas where it is desirable to intercept sheet flow before it crosses onto a section of roadway. Their principal advantage is their ability to intercept flow over a wide section. However, slotted inlets are very susceptible to clogging from sediments and debris, and are not recommended for use in environments where significant sediment or debris loads may be present. Slotted inlets on a longitudinal grade do have the same hydraulic capacity as curb openings when debris is not a factor.

L h

L

W

a. Grate Inlet

W

b. Curb Opening Inlet

L h

W

c. Combination Inlet

d. Slotted Drain Inlet

Figure 6-4: Classes of Storm Drain Inlets

6.4.3

Inlet Capacity Several agencies and manufacturers of grates have investigated inlet interception capacity. Hydraulic tests on grate inlets and slotted inlets included in this document were conducted by the Bureau of Reclamation for the Federal Highway Administration. Four of the grates selected for testing were rated highest in bicycle safety tests, three have designs and bar spacing similar to those proven bicycle-safe, and a parallel bar grate was used as a standard with which to compare the performance of others.

6-214


Pavement Drainage Figures 7.5 through 7.10 show the inlet grates for which design procedures were developed. For ease in identification, the following terms have been adopted: P-50: Parallel bar grate with bar spacing 48 mm (1-7/8 in) on center (Figure 6-5). P-50x100: Parallel bar grate with bar spacing 48 mm (1-7/8 in) on center and 10 mm (3/8 in) diameter lateral rods spaced at 102 mm (4 in) on center (Figure 6-5). P-30: Parallel bar grate with 29 mm (1-1/8 in) on center bar spacing (Figure 6-6). Curved Vane: Curved vane grate with 83 mm (3-1/4 in) longitudinal bar and 108 mm (4-1/4 in) transverse bar spacing on center Figure 6-7). 45° – 60 Tilt Bar: 45° tilt-bar grate with 57 mm (2-1/4 in) longitudinal bar and 102 mm (4 in) transverse bar spacing on center (Figure 6-8). 45° – 85 Tilt Bar: 45° tilt-bar grate with 83 mm (3-1/4 in) longitudinal bar and 102 mm (4 in) transverse bar spacing on center (Figure 6-8). 30° – 85 Tilt Bar: 30° tilt-bar grate with 83 mm (3-1/4 in) longitudinal bar and 102 mm (4 in) transverse bar spacing on center (Figure 6-9). Reticuline: Honeycomb pattern of lateral bars and longitudinal bearing bars (Figure 6-10).


6-215

Drainage Inlet Design

Figure 6-5: P-50 and P-50x100 Grates The interception capacity of curb-opening inlets has also been investigated by several agencies. Design procedures adopted for this Circular are largely derived from experimental work at Colorado State University for the Federal Highway Administration, as reported in both Hydraulics of Runoff from Developed Surfaces and Hydraulic Design of Depressed Curb-Opening Inlets.

6-216


Pavement Drainage

Figure 6-6: P-30 Grate


6-217


Figure 6-7: Curved Vane Grate

6-218


Pavement Drainage

Figure 6-8: 45 – 60-Degree and 45-85-Degree Tilt-Bar Grates


6-219


Figure 6-9: 30 – 85-Degree Tilt-Bar Grate

6-220


Pavement Drainage

Figure 6-10: Reticuline Grate

Factors Affecting Interception Capacity on Continuous Grades Inlet interception capacity, Qi, is the flow intercepted by an inlet under a given set of conditions. The efficiency of an inlet, E, is the percent of total flow that the inlet will intercept for those conditions. The efficiency of an inlet changes with changes in cross slope, longitudinal slope, total gutter flow, and, to a lesser extent, pavement roughness. In mathematical form, efficiency, E, is defined by the following equation:

E=

Where

Qi Q

(6.16)

E

=

Inlet efficiency

Q

=


Qi

=

Intercepted flow (m3/sec., ft3/sec.)

Flow that is not intercepted by an inlet is termed carryover or bypass and is defined as follows:

Qb = Q - Qi

(6.17)


6-221


Where

Qb

=

Bypass flow (m3/sec., ft3/sec.)

The interception capacity of all inlet configurations increases with increasing flow rates, and inlet efficiency generally decreases with increasing flow rates. Factors affecting gutter flow also affect inlet interception capacity. The depth of water next to the curb is the major factor in the interception capacity of both grate inlets and curbopening inlets. The interception capacity of a grate inlet depends on the amount of water flowing over the grate, the size and configuration of the grate and the velocity of flow in the gutter. The efficiency of a grate is dependent on the same factors and total flow in the gutter. Interception capacity of a curb-opening inlet is largely dependent on flow depth at the curb and curb opening length. Flow depth at the curb and consequently, curb opening inlet interception capacity and efficiency, is increased by the use of a local gutter depression at the curb-opening or a continuously depressed gutter to the proportion of the total flow adjacent to the curb. Top slab supports placed flush with the curb line can substantially reduce the interception capacity of curb openings. Tests have shown that such supports reduce the effectiveness of openings downstream of the support by as much as 50 percent and, if debris is caught at the support, interception by the downstream portion of the opening may be reduced to near zero. If intermediate top slab supports are used, they should be recessed several inches from the curb line and rounded in shape. Slotted inlets function in essentially the same manner as curb opening inlets, i.e., as weirs with flow entering from the side. Interception capacity is dependent on flow depth and inlet length. Efficiency is dependent on flow depth, inlet length and total gutter flow. The interception capacity of an equal length combination inlet consisting of a grate placed alongside a curb opening on a grade does not differ materially from that of a grate only. Interception capacity and efficiency are dependent on the same factors which affect grate capacity and efficiency. A combination inlet consisting of a curb opening inlet placed upstream of a grate inlet has a capacity equal to that of the curb opening length upstream of the grate plus that of the grate, taking into account the reduced spread and depth of flow over the grate because of the interception by the curb opening. This inlet configuration has the added advantage of intercepting debris that might otherwise clog the grate and deflect water away from the inlet.

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Pavement Drainage

Factors Affecting Inlet Interception Capacity in Sag Locations Grate inlets in sag vertical curves operate as weirs for shallow ponding depths and as orifices at greater depths. Between weir and orifice flow depths, a transition from weir to orifice flow occurs. The perimeter and clear opening area of the grate and the depth of water at the curb affect inlet capacity. The capacity at a given depth can be severely affected if debris collects on the grate and reduces the effective perimeter or clear opening area. Curb-opening inlets operate as weirs in sag vertical curve locations up to a ponding depth equal to the opening height. At depths above 1.4 times the opening height, the inlet operates as an orifice and between these depths, transition between weir and orifice flow occurs. The curb-opening height and length, and water depth at the curb affect inlet capacity. At a given flow rate, the effective water depth at the curb can be increased by the use of a continuously depressed gutter, by use of a locally depressed curb opening, or by use of an increased cross slope, thus decreasing the width of spread at the inlet. Slotted inlets operate as weirs for depths below approximately 50 mm (2 in) and orifices in locations where the depth at the upstream edge of the slot is greater than about 120 mm (5 in). Transition flow exists between these depths. For orifice flow, an empirical equation derived from experimental data can be used to compute interception capacity. Interception capacity varies with flow depth, slope, width, and length at a given spread. Slotted drains are not recommended in sag locations because they are susceptible to clogging from debris.

Comparison of Interception Capacity of Inlets on Grade In order to compare the interception capacity and efficiency of various inlets on grade, it is necessary to fix two variables that affect capacity and efficiency and investigate the effects of varying the other factor. Figure 6-11 shows a comparison of curbopening inlets, grates, and slotted drain inlets with gutter flow fixed at 0.09 m3/s (3.2 ft3/sec.), cross slope fixed at 3 percent, and longitudinal slope varied up to 10 percent. Conclusions drawn from an analysis of this figure are not necessarily transferable to other flow rates or cross slopes, but some inferences can be drawn that are applicable to other sets of conditions. Grate configurations used for interception capacity comparisons in this figure are described in “Inlet Capacity” on page 6-214. Figure 6-11 illustrates the effects of flow depth at the curb and curb-opening length on curb opening inlet interception capacity and efficiency. All of the slotted inlets and curb opening inlets shown in the figure lose interception capacity and efficiency as the longitudinal slope is increased because spread on the pavement and depth at the curb become smaller as velocity increases. It is accurate to conclude that curb opening inlet interception capacity and efficiency would increase with steeper cross slopes. It is also


6-223

Drainage Inlet Design accurate to conclude that interception capacity would increase and inlet efficiency would decrease with increased flow rates. Long curb-opening and slotted inlets compare favorably with grates in interception capacity and efficiency for conditions illustrated in Figure 6-11. The effect of depth at the curb is also illustrated by a comparison of the interception capacity and efficiency of depressed and undepressed curb-opening inlets. A 1.5 m (5 ft) depressed curb-opening inlet has about 67 percent more interception capacity than an undepressed inlet at 2 percent slope, 3 percent cross slope, and 0.085 m3/s (3 ft3/ sec.) gutter flow, and about 79 percent more interception capacity at an 8 percent slope. At low velocities, all of the water flowing in the section of gutter occupied by the grate, called frontal flow, is intercepted by grate inlets. Only a small portion of the flow outside of the grate, termed side flow, is intercepted. When the longitudinal slope is increased, water begins to skip or splash over the grate at velocities dependent on the grate configuration. Figure 6-11 shows that interception capacity and efficiency are reduced at slopes steeper than the slope at which splash-over begins. Splash-over for the less efficient grates begins at the slope at which the interception capacity curve begins to deviate from the curve of the more efficient grates. All of the 0.6 m by 0.6 m (2 ft by 2 ft) grates have equal interception capacity and efficiency at a flow rate of 0.085 m3/s (3 ft3/sec.), cross slope of 3 percent, and longitudinal slope of 2 percent. At slopes steeper than 2 percent, splash-over occurs on the reticuline grate and the interception capacity is reduced. At a slope of 6 percent, velocities are such that splashover occurs on all except the curved vane and parallel bar grates. From these performance characteristics curves, it can be concluded that parallel-bar grates and the curved vane grate are relatively efficient at higher velocities and the reticuline grate is least efficient. At low velocities, the grates perform equally. However, some of the grates such as the reticuline grate are more susceptible to clogging by debris than the parallel bar grate.

6-224


Pavement Drainage

Figure 6-11: Comparison of Inlet Interception Capacity, Slope Variable The capacity and efficiency of grates increase with increased slope and velocity if splash-over does not occur. This is because frontal flow increases with increased velocity, and all frontal flow will be intercepted if splash-over does not occur. Figure 6-11 also illustrates that interception by longer grates would not be substantially greater than interception by 0.6 m by 0.6 m (2 ft by 2 ft) grates. In order to capture more of the flow, wider grates would be needed. Figure 6-12 can be used for further study and comparisons of inlet interception capacity and efficiency. It shows, for example, that at a 6 percent slope, splash-over begins at about 0.02 m3/s (0.7 ft3/sec.) on a reticuline grate. It also illustrates that the interception capacity of all inlets increases and inlet efficiency decreases with increased discharge. This comparison of inlet interception capacity and efficiency neglects the effects of debris and clogging on the various inlets. All types of inlets, including curb-opening inlets, are subject to clogging, some being more susceptible than others. Attempts to simulate clogging tendencies in the laboratory have not been notably successful,


6-225

Drainage Inlet Design except to demonstrate the importance of parallel bar spacing in debris handling efficiency. Grates with wider spacings of longitudinal bars pass debris more efficiently. Except for reticuline grates, grates with lateral bar spacing of less than 0.1 m (4 in) were not tested so conclusions cannot be drawn from tests concerning debris handling capabilities of many grates currently in use. Problems with clogging are largely local since the amount of debris varies significantly from one locality to another. Some localities must contend with only a small amount of debris while others experience extensive clogging of drainage inlets. Since partial clogging of inlets on grade rarely causes major problems, allowances should not be made for reduction in inlet interception capacity except where local experience indicates an allowance is advisable.

Figure 6-12: Comparison of Inlet Interception Capacity, Flow Rate Variable

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Pavement Drainage

6.4.4

Interception Capacity of Inlets on Grade The interception capacity of inlets on grade is dependent on factors discussed in “Interception Capacity of Inlets on Grade” on page 6-227. In this section, design charts for inlets on grade and procedures for using the charts are presented for the various inlet configurations. Remember that for locally depressed inlets, the quantity of flow reaching the inlet would be dependent on the upstream gutter section geometry and not the depressed section geometry. Charts for grate inlet interception have been made and are applicable to all grate inlets tested for the Federal Highway Administration. The chart for frontal flow interception is based on test results, which show that grates intercept all of the frontal flow until a velocity is reached at which water begins to splash over the grate. At velocities greater than splash-over velocity, grate efficiency in intercepting frontal flow is diminished. Grates also intercept a portion of the flow along the length of the grate, or the side flow. A chart is provided to determine side-flow interception. One set of charts is provided for slotted inlets and curb-opening inlets, because these inlets are both side-flow weirs. The equation developed for determining the length of inlet required for total interception fits the test data for both types of inlets. A procedure for determining the interception capacity of combination inlets is also presented.

Grate Inlets Grates are effective highway pavement drainage inlets where clogging with debris is not a problem. Where clogging may be a problem, see Table 6-5 where grates are ranked for susceptibility to clogging based on laboratory tests using simulated leaves. This table should be used for relative comparisons only. When the velocity approaching the grate is less than the splash-over velocity, the grate will intercept essentially all of the frontal flow. Conversely, when the gutter flow velocity exceeds the splash-over velocity for the grate, only part of the flow will be intercepted. A part of the flow along the side of the grate will be intercepted, dependent on the cross slope of the pavement, the length of the grate, and flow velocity. 2.67

E0 =

Qw W = 1- 1Ł Tł Q

(6.18)

The ratio of frontal flow to total gutter flow, Eo, for a uniform cross slope is expressed by Equation 6.18:


6-227


Where

Q

=


Qw

=

Flow in width, W (m3/sec., ft3/sec.)

W

=

Width of depressed gutter or grate (m, ft)

T

=

Total spread of water (m, ft)

Example 6-2 and Chart 2 provide solutions of Eo for either uniform cross slopes or composite gutter sections. The ratio of side flow, Qs, to total gutter flow is:

Qs Q = 1 - w = 1 - Eo Q Q

(6.19)

The ratio of frontal flow intercepted to total frontal flow, Rf, is expressed by Equation 6.20:

R f = 1 - K c (V - Vo ) Where

Note:

6-228

(6.20)

Kc

=

0.295

V

=

Velocity of flow in gutter (m/sec., ft/sec.)

Vo

=

Gutter velocity where splash-over first occurs (m/ sec., ft/sec.)

Rf cannot exceed 1.0.


Pavement Drainage Table 6-5: Average Debris Handling Efficiencies of Grates Tested Rank

Grate

Longitudinal Slope 0.005

0.040

1

Curved Vane

45

61

2

30 – 85 deg. Tilt Bar

44

55

3


43

48

4

P-50

32

32

5

P-50x100

18

28

6


16

23

7

Reticuline

12

16

8

P-30

9

20

This ratio is equivalent to frontal flow interception efficiency. Chart 5 provides a solution for Equation 6.20, which takes into account grate length, bar configuration, and gutter velocity at which splash-over occurs. The average gutter velocity (total gutter flow divided by the area of flow) is needed to use Chart 5. This velocity can also be obtained from Chart 4. The ratio of side flow intercepted to total side flow, Rs, or side flow interception efficiency, is expressed by Equation 6.21:

K cV 1.8

Rs = 1 / 1 + 2.3 Ł Sx L ł Where

Kc

=

(6.21) 0.0828 SI, 0.15 U.S. customary

Chart 6 provides a solution to Equation 6.21.


6-229

Drainage Inlet Design A deficiency in developing empirical equations and charts from experimental data is evident in Chart 6. The fact that a grate will intercept all or almost all of the side flow where the velocity is low and the spread only slightly exceeds the grate width is not reflected in the chart. Error due to this deficiency is very small. In fact, where velocities are high, side flow interception may be neglected without significant error. The efficiency, E, of a grate is expressed as provided in Equation 6.22:

E = R f Eo + Rs (1 - Eo )

(6.22)

The first term on the right side of Equation 6.22 is the ratio of intercepted frontal flow to total gutter flow, and the second term is the ratio of intercepted side flow to total side flow. The second term is insignificant with high velocities and short grates. The interception capacity of a grate inlet on grade is equal to the efficiency of the grate multiplied by the total gutter flow:

ø Qi = EQ = Q Ø Œ ºR f Eo + Rs (1 - Eo )œ ß

(6.23)

The use of Charts 5 and 6 are illustrated in the following examples.

6-230


Pavement Drainage EXAMPLE 6-7

Given: Given the gutter section from Example 6-2 (illustrated in Figure 6.1 a.2) with T = 2.5 m (8.2 ft) W = 0.6 m (2.0 ft) S L = 0.010 S x = 0.02 n = 0.016 Continuous gutter depression, a = 50 mm (2 in) Find: The interception capacity of a curved vane grate 0.6 m by 0.6 m (2 ft by 2 ft) Solution: From Example 6-2, S w = 0.103 Eo = 0.70 Q = 0.06 m3 /s (2.3 cfs) Step 1. Compute the average gutter velocity 2

A = 0.5T 2 S x + 0.5 DW = 0.5 (2.5) (0.02)+ 0.5 (0.050)(0.6) A = 0.08m 2 (0.86 ft 2 ) V = Q A = 0.06 0.08 V = 0.75 m/s (2.5 ft/s) Step 2. Determine the frontal flow efficiency using Chart 5 R f = 1.0


6-231


Step 3. Determine the side flow efficiency using Equattion 6.20 or Chart 6 Rs = 1 Ø 1 + 0.0828V .8 ) S x L2.3 ø œ Œ ß º ( 1.8 2.3 Ø Rs = 1 Œ1 + (0.0828)(0.75) (0.02)(0.6) ø œ º ß Rs = 0.11 Step 4. Compute the interception capacity using Equation 6.22 ø Qi = Q Ø Œ ºR f Eo + Rs (1 - Eo )œ ß Ø ø Qi = (0.06)( º1.0)(0.70)+ (0.11)(1 - 0.70)ß Qi = 0.044 m3 /s (1.6 cfs) EXAMPLE 6-8

Given: Given the gutter section illustrated in Figure 6.1 a.1 with T = 3m(9.8 ft ) S L = 0.04 S x = 0.025 n = 0.016 Bicycle traffic not permitted Find: The interception capacity of the following grates: a. P-50; 0.6 m by 0.6 m (2.0 ft by 2.0 ft) b. Reticculine; 0.6 m by 0.6 m (2.0 ft by 2.0 ft) c. Grattes in a. and b. with a length of 1.2 m (4.0 ft) Solution: Step 1. Using Equation 6.2 or Chart 1, determine Q Q = K n S 1x.67 S L0.5T 2.67 1.67

Q = (0.376) (0.016)(0.025)

0.5

2.67

(0.04) (3)

Q = 0.19 m3 /s (6.6 cfs) Step 2. Determine E o from Equation 6.4 or Chart 2 W T = 0.6 3 = 0.2 Eo = Qw Q 2.67

Eo = 1 - (1 - W T ) Eo = 0.46

6-232


Pavement Drainage

Step 3. Using Equation 6.15 or Chart 4 compute gutter flow velocity V = 0.752 nS L0.5 S x0.67 T 0.67 0.5

V = 0.752 (0.016)(0.04)

0.67

0.67

(0.025) (3)

V = 1.66m / sec(5.4 ft / s ) Step 4. Using Equation 6.19 or Chart 5, determine the frontal flow efficiency for each graate. Using Equation 6.20 or Chart 6, determine the siide flow efficiency for each grate. Using Equation 6.22, compute the interception capacity of each grate. The following table summarizes the results: Table 6-6: Example 6-8 Results Grate

Size (width by length)

Frontal Flow Efficiency (Rf)

Side Flow Efficiency (Rs)

Interception Capacity

P-50

0.6m by 0.6m (2.0ft by 2.0ft)

1.0

0.036

0.091 cubic m/s

0.6m by 0.6m (2.0ft by 2.0ft)

0.9

0.6m by 1.2m (2.0ft by 4.0ft)

1.0

0.6m by 1.2m (2.0ft by 4.0ft)

1.0

Reticuline

P-50

Reticuline

(3.2 ft3/sec.) 0.036

0.082 cubic m/s (2.89 ft3/sec.)

0.155

0.103 cubic m/s (3.63 ft3/sec.)

0.155

0.103 cubic m/s (3.63 ft3/sec.)

The P-50 parallel bar grate will intercept about 14 percent more flow than the reticuline grate or 48 percent of the total flow as opposed to 42 percent for the reticuline grate. Increasing the length of the grates would not be cost-effective because the increase in side flow interception is small.

Curb-Opening Inlets Curb-opening inlets are effective in the drainage of highway pavements where flow depth at the curb is sufficient for the inlet to perform efficiently. Curb openings are less susceptible to clogging and offer little interference to traffic operation. They are a viable alternative to grates on flatter grades where grates would be in traffic lanes or would be hazardous for pedestrians or bicyclists.


6-233

Drainage Inlet Design Curb opening heights vary in dimension; however, a typical maximum height is approximately 100 to 150 mm (4 to 6 in). The length of the curb-opening inlet required for total interception of gutter flow on a pavement section with a uniform cross slope is expressed by Equation 6.24: 0.6

LT = K C Q

Where

0.42

S L0.3

1 ŁnS x ł

(6.24)

Kc

=


LT

=

Curb opening length required to intercept 100% of gutter flow (m, ft)

SL

=

Longitudinal slope

Q

=

Gutter flow (m3/sec., ft3/sec.)

The efficiency of curb opening inlets shorter than the length required for total interception is expressed by Equation 6.25: 1.8

L E = 1- 1Ł LT ł Where

L

(6.25) =

Curb opening length (m, ft)

Sx a S'w W

Figure 6-13: Depressed Curb-Opening Inlet Chart 7 is a nomograph for the solution of Equation 6.24, and Chart 8 provides a solution of Equation 6.25.

6-234


Pavement Drainage The length of inlet required for total interception by depressed curb-opening inlets or curb-openings in depressed gutter sections can be found by the use of an equivalent cross slope, Se, in Equation 6.24 in place of Sx. Se can be computed using Equation 6.26.

Se = S x + S ’w Eo Where

(6.26)

S'W

=

Cross-slope of the gutter measured from the crossslope of the pavement, Sx (m/m, ft/ft)

S'w

=

a/[1000W],(a/[12w]) (m, ft)

a

=


Eo

=

Ratio of flow in the depressed section to total gutter flow determined by gutter configuration upstream of inlet

Figure 6-13 shows the depressed curb inlet for Equation 6.26. Eo is the same ratio as used to compute the frontal flow interception of a grate inlet. As seen from Chart 7, the length of curb opening required for total interception can be significantly reduced by increasing the cross slope or the equivalent cross slope. The equivalent cross slope can be increased by use of a continuously depressed gutter section or a locally depressed gutter section. Using the equivalent cross slope, Se, Equation 6.24 becomes: 0.6

LT = KT Q

Where

0.42

KT

S L0.3

1 ŁnSe ł =

(6.27)


Equation 6.25 is applicable with either straight cross slopes or composite cross slopes. Charts 7 and 8 are applicable to depressed curb-opening inlets using Se rather than Sx. Equation 6.26 uses the ratio, Eo, in the computation of the equivalent cross slope, Se. Example 6-9 demonstrates the procedure to determine spread and then the example uses Chart 2 to determine Eo.


6-235


Given: A curb opening inlet with the following characteeristics: S L = 0.01 S x = 0.02 Q = 0.05 m3 /s(1.8cfs) n = 0.016 Find: (1) Qi for a 3 m (9.8 ft) curb opening. (2) Qi for a depressed 3 m (9.8 ft) curb opening inlet with a continuously depressed curb sectioon. a = 25 mm (1 in) W = 0.6 m (2 ft) Sollution (1): Step 1. Determine the length of curb openiing required for total interception of gutter flow ussing Equation 6.23 or Chart 7. 0.6

LT = 0.817Q 0.42 S L0.3 (1 (nS x )) 0.42

LT = 0.817 (0.05)

0.6

0.3 (0.01) (1 Øº(0.016)(0.02)øß)

LT = 7.29 m (23.6 ft) Step 2. Compute the curb opening efficiency using Equation 6..24 or Chart 8 L LT = 3 7.29 = 0.41 1.8

E = 1 - (1 - L LT )

1.8

E = 1 - (1 - 0.41)

E = 0.61 Step 3. Compute the interception capacity Qi = EQ = (0.61)(0.05) Qi = 0.031 m3 /s (1.1 cfs) Solution (2): Step 1. Use Equation 6.4 (Chart 2) and Equation 6.2 (Chartt 1) to determine the W/T ratio. Determine spread, T (Procedure from Example 6-2, Solution 2)

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Pavement Drainage

Assume: Qs = 0.018 m3 /s (0.64 cfs) Qw = Q - Qs = 0.05 - 0.018 - 0.032 m3 /s (1.1 cfs) Eo = Qw Q = 0.032 0.05 = 0.64 S w = S x + a W = 0.02 + (25 1000) 0.6 = 0.062 S w S x = 0.062 0.02 = 3.1 Use Equation 6.4 or Chart 2 to determine W T W T = 0.24 T = W (W T )= 0.6 0.24 = 2.5 m (8.2 ft) Ts = T - W = 2.5 - 0.6 Ts = 1.9 m (6.2 ft) Use Equation 6.2 or Chart 1 to obtain Qs Qs = K nS 1x.67 S L0.5Ts2.67 1.67

Qs = (0.376) (0.016)(0.0 02)

0.5

2.67

(0.01) (1.9)

Qs = 0.019 m3 /s (equals Qs assumed) Step 2. Determine efficiency of curb opening Se = S x + S ’w Eo = S x + (a W ) ø Eo = 0.02 + Ø º(25 1000) (0.6)ß(0.64) Se = 0.047 Using Equation 7.25 or Chart 7 0.6

ø LT = KT Q 0.42 S L0.3 Ø º1 (nSe )ß 0.42

LT = (0.817)(0.05)

0.6 0.3 (0.01) ØŒº1 ((0.016)(0.047))øœß

LT = 4.37 m (14.3 ft) Using Equation 6.24 or Chart 8 to obtain curb inlet efficiency L LT = 3 4..37 = 0.70 1.8

E = 1 - (1 - L LT )

1.8

E = 1 - (1 - 0.69)

E = 0.88 Step 3. Compute curb opening inflow using Equation 6.16 Qi = QE = (0.05)(0.88)


6-237


Qi = 0.044 m3 /s (1.55 cfs) The depressed curb opening inlet will intercept 1.5 times the flow intercepted by the undepressed curb opening.

Slotted Inlets Wide experience with the debris handling capabilities of slotted inlets is not available. Deposition in the pipe is the problem most commonly encountered. The configuration of slotted inlets makes them accessible for cleaning with a high pressure water jet.

Figure 6-14: Slotted Drain Inlet at an Intersection Slotted inlets are effective pavement drainage inlets, which have a variety of applications. They can be used on curbed or uncurbed sections and offer little interference to traffic operations. An installation is illustrated in Figure 6-14.

6-238


Pavement Drainage Flow interception by slotted inlets and curb-opening inlets is similar in that each is a side weir and the flow is subjected to lateral acceleration due to the cross slope of the pavement. Analysis of data from the Federal Highway Administration tests of slotted inlets with slot widths ≥ 45 mm (1.75 in) indicates that the length of slotted inlet required for total interception can be computed by Equation 6.24. Chart 7, is therefore applicable for both curb-opening inlets and slotted inlets. Similarly, Equation 6.25 is also applicable to slotted inlets and Chart 8 can be used to obtain the inlet efficiency for the selected length of inlet. Use Charts 7 and 8 for slotted inlets the same way you would for curb-opening inlets. Additional examples to demonstrate the use of the charts are not provided here for that reason. It should be noted, however, that it is much less expensive to add length to an existing slotted inlet to increase interception capacity than it is to add length to an existing curb-opening inlet. Combination Inlets

Figure 6-15: Combination Curb-Opening, 45-Degree Tilt-Bar Grate Inlet The interception capacity of a combination inlet consisting of a curb opening and grate placed side-by-side, as shown in Figure 6-15, is no greater than that of the grate alone. Capacity is computed by neglecting the curb opening. A combination inlet is sometimes used with a part of the curb opening placed upstream of the grate as illustrated in Figure 6-16. The curb opening in such an installation intercepts debris, which


6-239

Drainage Inlet Design might otherwise clog the grate and is called a sweeper inlet. A sweeper combination inlet has an interception capacity equal to the sum of the curb opening upstream of the grate plus the grate capacity, except that the frontal flow and thus the interception capacity of the grate is reduced by interception by the curb opening.

Figure 6-16: Sweeper Combination Inlet The following example illustrates computation of the interception capacity of a combination curb-opening grate inlet with a portion of the curb opening upstream of the grate.

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Pavement Drainage EXAMPLE 6-10

Given: A combination curb opening grate inlet with a 3 m (9.8 ft) curb opening, 0.6 m by 0.6 m (2 ft by 2 ft) curved vane grate placed adjacent to the downstreeam 0.6 m (2 ft) of the curb opening. This inlet is located in a gutter section having the following characterristics: W = 0.6 m Q = 0.05 m3 /s (1.8 cfs) SL = 0.01 Sx = 0.02 n = 0.016 Gutter depression, D = 25 mm (1.0 in) Find: Interception capacity, Qi Solution: Step 1. Compute the interception capacity of the curb opening upstream of the grate, Qic . L = 3 m - 0.6 m = 2.4 m (7.9 ft) From Example 6-9, Solution 2, Step 2 LT = 4.37 m (14.0 ft) L LT = 2.4 4.37 = 0.55 1.8

E = 1 - (1 - L LT )

{Equation 6.24 or Chart 8}

1.8

E = 1 - (1 - 0.55) E = 0.76

Qic = EQ = (0.76)(0.05)= 0.038 m3 /s (1.3 cfs) Step 2. Compute the interception capacity of the grate. Flow at grate = Qg = Q - Qic = 0.05 = 0.038 Qg = 0.012 m3 /s (0.4 cfs) Determine spread, T (Procedure from Examp ple 6-2, Solution 2) Assume Qs - 0.0003 m3 /s (0.01 cfs) Qw = Q - Qs = 0.0120 - 0.0003 = 0.0117 m3 /s (0.41 cfs) Eo = Qw Q = 0.0117 0.0120 = 0.97


6-241


S w S x = 0.062 0.02 = 3.1 W T=1

0.375 - 1 (S w S x )+ 1 1 Ø 1 (1 Eo - 1))(S w S x )+ 1ø ( Œ œ º ß Ł ł

W T=1

0.375 1 Ø 1 (1 0.97 - 1))(3.1)+ 1ø - 1 (3.1)+ 1 ( Œ œ º ß Ł ł

W T = 0.62 T = W (W T )= 0.6 0.62 = 0.9 97 m (3.2 ft) Ts = T - W - 0.97 - 0.60 = 0.37 m (1.2 ft) Qs = 0.0003 m3 /s (0.01 cfs) {Chart 1 or Equation 6.2} Qs assumed = Qs calculated Determine velocity, V 2 ø V = Q A= Q Ø Œ0.5T S x + 0.5 DW ß œ º 2 V = 0.0115 Ø (0.5)(0.97) (0.02)+ (0.5)(25 1000)(0.6)øœ Œ º ß V = 0.68 m/s (2.23 ft/s) R f = 1.0 {Chart 5} Rs = 1 1 + (0.0828V 1.8 ) (S x L2.3 ) {Equation 6.20 or Chart 6}

(

)

1.8 2.3 3 Rs = 1 1 + Ø (0.0828)(0.68) øœ ØŒ(0.02)(0.6) øœ Œ º ßº ß Rs = 0.13

(

)

ØR E + R (1 - E )ø {Equation 6.22} Qig = Qg Œ s o ß œ ºf o ø Qig = 0.0115 Ø º(1.0)(0.97)+ (0.13)(1 - 0.97)ß Qig = 0.0112 m3 /s (0.40 cfs) Step 3. Compute the total interception capacity. (Note: Intterception capacity of curb opening adjacent to grate was neglected.) Qi = Qic + Qig = 0.0385 + 0.0112 Qi = 0.0497 m3 /s (1.76 cfs)(approximately 100% of local initial flow) The use of depressed inlets and combination inlets enhances the interception capacity of the inlet. Example 6-7 determined the interception capacity of a depressed curved vane grate, 0.6 m by 0.6 m (2 ft by 2 ft), Example 6-9 for an undepressed curb opening inlet, length = 3.0 m (9.8 ft) and a depressed curb opening inlet, length = 3.0 m (9.8 ft), and Example 6-10 for a combination of 0.6 m by 0.6 m (2 ft by 2 ft) depressed

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Pavement Drainage curve vane grate located at the downstream end of 3.0 m (9.8 ft) long depressed curb opening inlet. The geometries of the inlets and the gutter slopes were consistent in the examples and Table 6-7 summarizes a comparison of the intercepted flow of the various configurations. Table 6-7: Comparison of Inlet Interception Capabilities Inlet Type

Intercepted Flow, Qi

Curved Vane—Depressed

0.033 cubic m/s (1.2 ft3/sec.) (Example 6-7)

Curb Opening—Undepressed


Curb Opening—Depressed


Combination Inlet (Curved Vane and Curb Opening)— Depressed


From Table 6-7, it can be seen that the combination inlet intercepted approximately 100% of the total flow whereas the curved vane grate alone only intercepted 66% of the total flow. The depressed curb opening intercepted 90% of the total flow. However, if the curb opening was undepressed, it would have only intercepted 62% of the total flow.

6.4.5

Interception Capacity of Inlets in Sag Locations Inlets in sag locations operate as weirs under low head conditions and as orifices at greater depths. Orifice flow begins at depths dependent on the grate size, the curb opening height, or the slot width of the inlet. At depths between those at which weir flow definitely prevails and those at which orifice flow prevails, flow is in a transition stage. At these depths, control is ill-defined and flow may fluctuate between weir and orifice control. Design procedures presented here are based on a conservative approach to estimating the capacity of inlets in sump locations. The efficiency of inlets in passing debris is critical in sag locations because all runoff which enters the sag must be passed through the inlet. Total or partial clogging of inlets in these locations can result in hazardous ponded conditions. Grate inlets alone are not recommended for use in sag locations because of the tendencies of grates to become clogged. Combination inlets or curb-opening inlets are recommended for use in these locations.


6-243


Grate Inlets A grate inlet in a sag location operates as a weir to depths dependent on the bar configuration and size of the grate and as an orifice at greater depths. Grates of larger dimension will operate as weirs to greater depths than smaller grates or grates with less opening area. The capacity of grate inlets operating as weirs is:

Qw = Cw 2Wd11.5 + Cw Ld 21.5 Where

(6.28)

W

=

Width of the grate (m, ft)

CW

=


d1

=

Flow depth at middle of grate(m, ft)

d2

=

Flow depth at side of grate opposite the curb (m, ft)

The capacity of a grate inlet operating as an orifice is: 0.5

Qi = Co Ag (2 gd ) Where

(6.29)

Co

=

Orifice coefficient 0.67

Ag

=

Clear opening of the grate (m2, ft2)

g

=

Gravitational acceleration (9.81 m/sec.2, 32.16 ft/ sec.2)

Use of Equation 6.29 requires the clear area of opening of the grate. Tests of three grates for the Federal Highway Administration showed that for flat bar grates, such as the P-50x100 and P-30 grates, the clear opening is equal to the total area of the grate less the area occupied by longitudinal and lateral bars. The curved vane grate performed about 10 percent better than a grate with a net opening equal to the total area less the area of the bars projected on a horizontal plane. That is, the projected area of the bars in a curved vane grate is 68 percent of the total area of the grate leaving a net opening of 32 percent, however the grate performed as a grate with a net opening of 35 percent. Tilt-bar grates were not tested, but exploration of the above results would indicate a net opening area of 34 percent for the 30-degree tiltbar and zero for

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Pavement Drainage the 45-degree tilt-bar grate. Obviously, the 45-degree tilt-bar grate would have greater than zero capacity. Tilt-bar and curved vane grates are not recommended for sump locations where there is a chance that operation would be as an orifice. Opening ratios for the grates are given on Chart 9. Chart 9 is a plot of Equations 6.28 and 6.29 for various grate sizes. The effects of grate size on the depth at which a grate operates as an orifice is apparent from the chart. Transition from weir to orifice flow results in interception capacity less than that computed by either the weir or the orifice equation; this capacity can be approximated by drawing in a curve between the lines representing the perimeter and net area of the grate to be used. Example 6-11 illustrates use of Equations 6.28 and 6.29 and Chart 9. EXAMPLE 6-11

Given: Under design storm conditions a flow of 0.10 m3 /s (3.5 cfs) bypasses each of the flanking inlets resuulting in a total flow to the sag inlet of 0.23 m3 /s (8.1 cfs). Also, Sx = 0.05 n = 0.016 Tallowabble = 3 m (9.8 ft) Find: Find the grate size required and depth at curb for the sag inlet assuming 50% clog gging. Solution: Step 1. Determine the required grate perimeter. d = TS x = (3.0)(0.05) d = 0.15 m (0.49 ft) 1.5 ø P = Qi Ø ŒCw d ß œ {Equation 6.25 or Chart 9} º 1.5 P = (0.23) Ø (1.66)(0.15) øœ Œ º ß P = 2.4 m (8 ft) Some assumptions must be made regarding the nature of the clogging in order to compute the capacity of a partially clogged grate. If the area of a grate is 50 percent covered by debris so that the debris-covered portion does not contribute to interception, the effective perimeter will be reduced by a lesser amount than 50 percent. For example, if a 0.6 m by 1.2 m (2 ft by 4 ft) grate is clogged so that the effective width is 0.3 m (1 ft), then the perimeter, P = 0.3 + 1.2 + 0.3 = 1.8 m (6 ft), rather than 2.4 m (8


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Drainage Inlet Design ft), the total perimeter, or 1.2 m (4 ft), half of the total perimeter. The area of the opening would be reduced by 50 percent and the perimeter by 25 percent. Therefore, assuming 50 percent clogging along the length of the grate, a 1.2 m by 1.2 m (4 ft by 4 ft), 0.6 m by 1.8 m (2 ft by 6 ft), or a .9 m by 1.5 m (3 ft by 5 ft) grate would meet requirements of a 2.4 m (8 ft) perimeter 50 percent clogged.

Assuming 50 percent clogging along the grate lenggth, Peffective = 2.4 m = (0.5)(2)W + L if W = 0.6 m then L ‡ 1.8 m (6 ft) if W = 0.9 m then L ‡ 1.5 m (5 ft) Select a double 0.6 m by 0.9 m (2 ftt by 3 ft) grate. Peffective = (0.5)(2)(0.6) + (1.8) Peffective = 2.4 m (8 ft) Step 2. Check depth of flow at curb using Equation 6.25 or Chart 9. ø0.67 d= Ø Q C P ( ) w º ß 2.67 d= Ø 0.23 ((1.66)(2.4))ø Œ œ º ß d = 0.15 m (0.5 ft) Therefore, OK. Conclusion: A double 0.6 m by 0.9 m (2 ft by 3 ft) grate 50 percent clogged is adequate to intercept the design storm flow at a spread, which does not exceed design spread. However, the tendency of grate inlets to clog completely warrants consideration of a combination inlet or curb-opening inlet in a sag where ponding can occur, and flanking inlets on the low gradient approaches.

Curb-Opening Inlets The capacity of a curb-opening inlet in a sag depends on water depth at the curb, the curb opening length, and the height of the curb opening. The inlet operates as a weir to depths equal to the curb opening height and as an orifice at depths greater than 1.4 times the opening height. At depths between 1.0 and 1.4 times the opening height, flow is in a transition stage. Spread on the pavement is the usual criterion for judging the adequacy of a pavement drainage inlet design. It is also convenient and practical in the laboratory to measure depth at the curb upstream of the inlet at the point of maximum spread on the pavement. Therefore, depths at the curb measurements from experiments coincide with the

6-246


Pavement Drainage depth at curb of interest to designers. The weir coefficient for a curb opening inlet is less than the usual weir coefficient for several reasons, the most obvious of which is that depth measurements from experimental tests were not taken at the weir, and drawdown occurs between the point where measurement were made and the weir. The weir location for a depressed curb-opening inlet is at the edge of the gutter, and the effective weir length is dependent on the width of the depressed gutter and the length of the curb opening. The weir location for a curb-opening inlet that is not depressed is at the lip of the curb opening, and its length is equal to that of the inlet, as shown in Chart 10. The equation for the interception capacity of a depressed curb-opening inlet operating as a weir is:

Qi = Cw (L + 1.8W )d 1.5 Where

(6.30)

Cw

=


L

=

Length of curb opening (m, ft)

W

=

Lateral width of depression (m, ft)

d

=

Depth at curb, measured from the normal crossslope—d = TSx (m, ft)

The weir equation is applicable to depths at the curb approximately equal to the height of the opening plus the depth of the depression. Thus, the limitation on the use of Equation 6.30 for a depressed curb-opening inlet is:

d £ h + a (1000) SI or d £ h + a 12 U.S. customary Where

h

=


a

=

Depth of depression (mm, in)

(6.31)

Experiments have not been conducted for curb-opening inlets with a continuously depressed gutter, but it is reasonable to expect that the effective weir length would be as great as that for an inlet in a local depression. Use of Equation 6.30 will yield conservative estimates of the interception capacity. The weir equation for curb-opening inlets without depression becomes:


6-247


Qi = Cw Ld 1.5

(6.32)

Without depression of the gutter section, the weir coefficient, Cw, becomes 1.60 (3.0, U.S. customary system). The depth limitation for operation as a weir becomes d ≤ h. At curb-opening lengths greater than 3.6m (12 ft), Equation 6.32 for non-depressed inlet produces intercepted flows which exceed the values for depressed inlets computed using Equation 6.30. Since depressed inlets will perform at least as well as non-depressed inlets of the same length, Equation 6.32 should be used for all curb opening inlets having lengths greater than 3.6 m (12 ft). Curb-opening inlets operate as orifices at depths greater than approximately 1.4 times the opening height. The interception capacity can be computed by Equation 6.33 and Equation 6.34. These equations are applicable to depressed and undepressed curbopening inlets. The depth at the inlet includes any gutter depression. 0.5

Qi = Co hL (2 gd o )

(6.33)

Or 0.5 Ø h ø Qi = Co Ag Œ2 g di œ Œ ß º Ł 2 łœ

Where

(6.34)

Co

=

Orifice coefficient 0.67

do

=

Effective head on the center of the orifice throat (m, ft)

L

=

Length of the orifice opening (m, ft)

Ag

=

Clear area of the opening (m2, ft2)

di

=

Depth at lip of curb opening (m, ft)

h

=

Height of curb opening orifice (m, ft) h = TSx + a (a/12 U.S. customary)

The height of the orifice in Equations 6.33 and 6.34 assumes a vertical orifice opening. As illustrated in Figure 6-17, other orifice throat locations can change the effective depth on the orifice and the dimension (di – h/2). A limited throat width could reduce the capacity of the curb-opening inlet by causing the inlet to go into orifice flow at depths less than the height of the opening.

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Pavement Drainage For curb-opening inlets with other than vertical faces (see Figure 6-17), Equation 6.33 can be used with: Where

h

h

=

Orifice throat width (m, ft)

do

=

Effective head on the center of the orifice throat

do

di

do

do = di

d o = d i -(h/2) h a. Horizontal Throat

c. Vertical Throat

0

do

h d o = d i -(h/2)Sin 0 b. Inclined Throat Figure 6-17: Curb Opening Inlets Chart 10 provides solutions for Equations 6.30 and 6.33 for depressed curb-opening inlets, and Chart 11 provides solutions for Equations 6.32 and 6.33 for curb-opening inlets without depression. Chart 12 is provided for use for curb openings with other than vertical orifice openings. Example 6-12 illustrates the use of Charts 11 and 12.


6-249


Given: Curb opening inlet in a sump location with L=2.5 m (8.2 ft) h=0.13 m (0.43 ft) (1) Undepresseed curb opening Sx =0.02 T=2.5 m (8.2 ft) (2) Depressed curb opening Sx =0.02 a=25 mm (1 in) W=0.6 m (2 ft) T=2.5 m (8.2 ft) Find: Qi Solution (1): Step 1. Determine depth at curb. d = TS x = (2.5)(0.02) d = 0.05 m (0.16 ft) d = 0.05 m £ h = 0.013 m, therefore weir controls Step 2. Use Equation 6.31 or Chart 11 to findd Qi . Qi = Cw Ld 1.5 1 .5

Qi = (1.60)(2.5)(0.05) = 0.045 m3 /s (1.6 cfs)

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Pavement Drainage

Solution(2): Step 1. Determine depth at curb, d i . di = d + a di = S x T + a = (0.02)(2.5) + 25 1000 di = 0.075 m (0.25 ft) di = 0.075 m < h = 0.13 m, therefore weir flow controls Step 2. Use Equation 7.29 or Chart 10 to find Qi . P = L + 1.8W = 2.5 m + (1.8)(0.6) P = 3.58 m (11.7 ft) Qi = Cw (L + 1.8W )d 1.5 1.5

Qi = (1.25)(3.58)(0.05) = 0.048 m3 /s (1.7 cfs) The depressed curb opening inlet has 10 percent more capacity th han an inlet without depression. Slotted Inlets Slotted inlets in sag locations perform as weirs to depths of about 0.06 m (0.2 ft), dependent on slot width. At depths greater than about 0.12 m, (0.4 ft), they perform as orifices. Between these depths, flow is in a transition stage. The interception capacity of a slotted inlet operating as a weir can be computed by an equation of the form:

Qi = Cw L (d 1.5 ) Where

(6.35)

Cw

=

Weir coefficient that varies with flow depth and slot length (typically 1.4 SI and 2.48 U.S. customary)

L

=

Length of slot (m, ft)

d

=

Depth at curb measured from the normal crossslope (m, ft)

The interception capacity of a slotted inlet operating as an orifice can be computed by Equation 6.36:

Qi = 0.8 LW (2 gd )0.5


(6.36)

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Where

W

=

Width of slot (m, ft)

L

=

Length of slot (m, ft)

d

=

Depth of water at slot for d ≤ 0.12 m or d ≤ 0.4 ft

g

=


For a slot width of 45 mm (1.75 in), Equation 6.36 becomes:

Qi = 0.16 L0d.5

(6.37)

Chart 13 provides solutions for weir and orifice flow conditions as represented by Equations 6.35 and 6.36. As indicated in Chart 13, the transition between weir and orifice flow occurs at different depths. To conservatively compute the interception capacity of slotted inlets in sump conditions in the transition area, original conditions should be assumed. Due to clogging characteristics, slotted drains are not recommended in sag locations. EXAMPLE 6-13

Given: A slotted inlet located along a curb having a sllot width of 45 mm (1.75 in). The gutter flow at the upstream end of the inlet is 0.14 m3 /s (4.9 cfs) Find: The length of slotted inlet required to limit maximum deepth at the curb to 0.09 m (3.6 in) assuming no cloggging. Solution: Using Equation 6.36 or Chart13 L = Qi Ø (0.16)(d 0.5 )øœß Œ º 0.5 L = (0.14) Ø (0.16)(0.09) øœ Œ º ß L = 2.91 m (9.5 ft)

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Pavement Drainage

Combination Inlets Combination inlets consisting of a grate and a curb opening are considered advisable for use in sags where hazardous ponding can occur. Equal length inlets refer to a grate inlet placed along side a curb-opening inlet, both of which have the same length. A sweeper inlet refers to a grate inlet placed at the downstream end of a curb-opening inlet. The curb-opening inlet is longer than the grate inlet and intercepts the flow before the flow reaches the grate. The sweeper inlet is more efficient than the equal length combination inlet and the curb opening has the ability to intercept any debris, which may clog the grate inlet. The interception capacity of the equal length combination inlet is essentially equal to that of a grate alone in weir flow. In orifice flow, the capacity of the equal length combination inlet is equal to the capacity of the grate plus the capacity of the curb opening. Equation 6.28 and Chart 9 can be used for weir flow in combination inlets in sag locations. Assuming complete clogging of the grate, Equations 6.30, 6.32, and 6.33 and Charts 10, 11 and 12 for curb-opening inlets are applicable. Where depth at the curb is such that orifice flow occurs, the interception capacity of the inlet is computed by adding Equations 6.29 and 6.34 as follows: 0.5

0.5

Qi = 0.67 Ag (2 gd ) + 0.67 hL (2 gd o ) Where

(6.38)

Ag

=

Clear area of the grate (m2, ft2)

g

=


d

=

Depth at the curb (m, ft)

h

=

Height of the curb-opening orifice (m, ft)

L

=

Length of the curb opening (m, ft)

do

=

Effective depth at the center of the curb-opening orifice (m, ft)

Trial and error solutions are necessary for determining the depth at the curb for a given flow rate using Charts 9, 10, and 11 for orifice flow. Different assumptions for clogging of the grate can also be examined using these charts as illustrated by Example 614.


6-253


Given: A combination inlet in a sag location with the following characteristics: Grate - 0.6 m by 1.2 m (2 ft by 4 ft) P-50 Curb Opening - L = 1.2 m (4 ft) h=0.1 m (3.9 in) Q=0.15 m3 /s (5.3 cfs) Sx =0.03 Find: Depth at curb and spread for: (1) Grate cllear of clogging (2) Grate 100 percent clogged Sollution (1): Step 1. Compute depth at curb. Asssuming grate controls interception: P = 2W + L = 2(0.66) + 1.2 P = 2.4 m (7.9 ft) From Equation 6.27 or Chart 9

6-254


Pavement Drainage

ø0.67 d= Ø ºQi (Cw P )ß 0.67 d= Ø 0.15) {(1.66)(2.4)}ø = 0.11 m (0.36 ft) ( Œ œ º ß Step 2. Compute associated d spread. T = d S x = (0.11) (0.03) T = 3.67 m (12 ft) Solution (2): Step 1. Compute depth at curb. Assuming grate is clogged, use Chart 11 or Equation 6.33 with Q = 0.15 m3 /s (5.3 cfs) 2

d = {Qi (Co hL)} d=

(2 g )+ h 2 2

{(0.15) Øº(0.67)(0.10)(1.2)øß}

Ø(2)(9.8 81)ø º ß+ (0.1 2)= 0.24 m (0.8 ft)

Step 2. Compute associiated spread. T = d S x = (0.24) (0.03) T = 8.0 m (26.2 ft) Interception by the curb opening only will be in a transition stage between weir and orifice flow with a depth at the curb of about 0.24 m (0.8 ft). Depth at the curb and spread on the pavement would be almost twice as great if the grate should become completely clogged.

6.4.6

Inlet Locations The location of inlets is determined by geometric controls which require inlets at specific locations, the use and location of flanking inlets in sag vertical curves, and the criterion of spread on the pavement. In order to adequately design the location of the inlets for a given project, you need the following information: •

A layout or plan sheet suitable for outlining drainage areas

•

Road profiles

•

Typical cross sections

•

Grading cross sections

•

Superelevation diagrams

•

Contour maps


6-255


Geometric Controls There are a number of locations where inlets may be necessary with little regard to contributing drainage area. These locations should be marked on the plans prior to any computations regarding discharge, water spread, inlet capacity, or flow bypass, as described in the following examples: •

At all low points in the gutter grade

•

Immediately upstream of median breaks, entrance/exit ramp gores, cross walks, and street intersections (i.e. at any location where water could flow onto the travelway)

•

Immediately upgrade of bridges (to prevent pavement drainage from flowing onto bridge deck)

•

Immediately downstream of bridges (to intercept bridge deck drainage)

•

Immediately up grade of cross slope reversals

•

Immediately up grade from pedestrian cross walks

•

At the end of channels in cut sections

•

On side streets immediately up grade from intersections

•

Behind curbs, shoulders or sidewalks to drain low areas

In addition to the areas identified above, runoff from areas draining towards the highway pavement should be intercepted by roadside channels or inlets before it reaches the roadway. This applies to drainage from cut slopes, side streets, and other areas alongside the pavement. Curbed pavement sections and pavement drainage inlets are inefficient means for handling extraneous drainage.

Inlet Spacing on Continuous Grades Design spread is the criterion used for locating storm drain inlets between those required by geometric or other controls. The interception capacity of the upstream inlet will define the initial spread. As flow is contributed to the gutter section in the downstream direction, spread increases. The next downstream inlet is located at the point where the spread in the gutter reaches the design spread. Therefore, the spacing of inlets on a continuous grade is a function of the amount of upstream bypass flow, the tributary drainage area, and the gutter geometry. For a continuous slope, the designer may establish the uniform design spacing between inlets of a given design if the drainage area consists of pavement only or has reasonably uniform runoff characteristics and is rectangular in shape. In this case, the time of concentration is assumed to be the same for all inlets. The following procedure and example illustrates the effects of inlet efficiency on inlet spacing.

6-256


Pavement Drainage Use the computation sheet shown in Figure 6-18 and perform the steps in the following procedure: Step 1—Complete the blanks at the top of the sheet to identify the job by state project number, route, date, and your initials. Step 2—Mark on a plan the location of inlets which are necessary even without considering any specific drainage area. Step 3—Start at a high point, at one end of the job if possible, and work towards the low point. Then begin at the next high point and work backwards toward the same low point. Step 4—To begin the process, select a trial drainage area approximately 90 m to 150 m (300 to 500 ft) long below the high point and outline the area on the plan. Include any area that may drain over the curb, onto the roadway. However, where practical, drainage from large areas behind the curb should be intercepted before it reaches the roadway or gutter. Step 5—(Col. 1, Col. 2, Col. 19) Describe the location of the proposed inlet by number and station and record this information in columns 1 and 2. Identify the curb and gutter type in column 19, Remarks. A sketch of the cross section should be prepared. Step 6—(Col. 3) Compute the drainage area (hectares) outlined in step 4 and record in column 3. Step 7—(Col. 4) Determine the runoff coefficient, C, for the drainage area. Step 8—(Col. 5) Compute the time of concentration, tc, in minutes, for the first inlet and record in column 5. The time of concentration is the time for the water to flow from the most hydraulically remote point of the drainage area to the inlet. The minimum time of concentration is 5 minutes. Step 9—(Col. 6) Using the time of concentration, determine the rainfall intensity from the Intensity-Duration-Frequency (IDF) curve for the design frequency. Enter the value in column 6. Step 10—(Col. 7) Calculate the flow in the gutter using Q = CIA / Kc. The flow is calculated by multiplying column 3 times column 4 times column 6 divided by Kc. Using the SI system of units, Kc = 360 (= 1 for U.S. customary units). Enter the flow value in column 7. Step 11—(Col. 8) From the roadway profile, enter in column 8 the gutter longitudinal slope, SL, at the inlet, taking into account any superelevation.


6-257

Drainage Inlet Design Step 12—(Col. 9, Col. 13) From the cross section, enter the cross slope, Sx, in column 9 and the grate or gutter width, W, in column 13. Step 13—(Col. 11, Col. 10) For the first inlet in a series, enter the value from column 7 into column 11, since there was no previous bypass flow. Additionally, if the inlet is the first in a series, enter 0 into column 10. Step 14—(Col. 14, Col. 12) Determine the spread, T, by using Equations 6.2 and 6.4 or Charts 1 and 2 and enter the value in column 14. Also, determine the depth at the curb, d, by multiplying the spread by the appropriate cross slope, and enter the value in column 12. Compare the calculated spread with the allowable spread as determined by the design criteria outlined in “Design Frequency and Spread” on page 6-186. Additionally, compare the depth at the curb with the actual curb height in column 19. If the calculated spread, column 14, is near the allowable spread and the depth at the curb is less than the actual curb height, continue on to step 15. Else, expand or decrease the drainage area up to the first inlet to increase or decrease the spread, respectively. The drainage area can be expanded by increasing the length to the inlet and it can be decreased by decreasing the distance to the inlet. Then, repeat steps 6 through 14 until appropriate values are obtained. Step 15—(Col. 15) Calculate W/T and enter the value in column 15. Step 16—(Col. 16) Select the inlet type and dimensions and enter the values in column 16. Step 17—(Col. 17) Calculate the flow intercepted the grate, Qi, and enter the value in column 17. Use Equations 6.18 and 6.15 or Charts 2 and 4 to define the gutter flow. Use Chart 5 and Equation 6.21 or Chart 6 to define the flow intercepted by the grate. Use Equations 6.24 and 6.25 or Charts 7 and 8 for curb opening inlets. Finally, use Equation 6.25 to determine the intercepted flow. Step 18—(Col. 18) Determine the bypass flow, Qb, and enter into column 18. The bypass flow is column 11 minus column 17. Step 19—(Col. 1-4) Proceed to the next inlet down the grade. To begin the procedure, select a drainage area approximately 90 m to 120 m (300 to 400 ft) below the previous inlet for a first trial. Repeat steps 5 through 7 considering only the area between the inlets. Step 20—(Col. 5) Compute the time of concentration for the next inlet based upon the area between the consecutive inlets and record this value in column 5. Step 21—(Col. 6) Determine the rainfall intensity from the IDF curve based upon the time of concentration determined in step 19 and record the value in column 6. Step 22—(Col. 7) Determine the flow in the gutter and record the value in column 7.

6-258


Pavement Drainage Step 23—(Col. 11) Record the value from column 18 of the previous line into column 10 of the current line. Determine the total gutter flow by adding column 7 and column 10 and record in column 11. Step 24—(Col. 12, Col. 14) Determine the spread and the depth at the curb as outlined in step 14. Repeat steps 18 through 24 until the spread and the depth at the curb are within the design criteria. Step 25—(Col. 16) Select the inlet type and record in column 16. Step 26—(Col. 17) Determine the intercepted flow in accordance with step 17. Step 27—(Col. 18) Calculate the bypass flow by subtracting column 17 from column 11. This completes the spacing design for the inlet. Step 28—Repeat steps 19 through 27 for each subsequent inlet down to the low point.


6-259


Figure 6-18: Inlet Spacing Computation Sheet

6-260


Pavement Drainage

Figure 6-19: Storm Drainage System for Example 6-15


6-261


Given: The storm drainage system illustrated in Figure 6.19 with the following roadway characteristics: n=0.016 Sx =0.02 SL =0.03 Allowable spread = 2.0 m (6.6 ft) Gutter and shoulder cross slope = 0.044 For maintenance reasons, inlet spacing is limited to o 110 m (360 ft) Find: The maximum design inlet spacingg for a 0.6 m wide by 0.9 m long (2 ft by 3 ft) P 50 x 100 grate, during a 10-year storm event. Solution: Use the inlet computation sheet shown in Figure 6.20. The entries are shown in Figure 6.20. Steps 1-44. The computations can begin at either of the inlets located at station 20+00. The initial drainage areaa consists of a 13 m wide roadway section with a length of 200 m. The top of the drainage basin iss located at station 22+00. Step 5. Col. 1 - Inleet # 40 Col. 2 Station 20+00 Col. 19 Composite gutter with a curb height = 0.15 m (0.50 ft) Step 6. Col. 3 - Distance froom top of drainage area to first inlet = 22+00 - 20+00 = 200 m Width = 13 m Drainage area = (200)(13) = 2600 0 m 2 = 0.26 ha (0.64 ac) Step 7. Col. 5 - Runoff coefficient, C = 0.73 Step 8. Col. 5 - First caalculate velocity of gutter flow using Equation 3-4 and Table3-3. 0.5

V = KS 0p.5 = (0.619)(3.0) = 1.1 m/s (3.5 ft/s) Calculate the time of concentration, t c . ø tc = L [60V ]= (200) Ø º(60)(1.1)ß

6-262


Pavement Drainage

tc = 3.0 min (use 5 minutes minimum) Step 9. Col. 6 - Determine rainfall intensity, I,, from IDF curve. I = 180 mm/hr Step 10. Col. 7 - Determine gutter flow rate, Q, ussing Equation 3-1. Q = CIA K c = (0.73)(180)(0.26) (360)= 0.095 m3 /s (3.4 cfs) Step 11. Col. 8 - SL = 0.03 m/m Step 12. Col. 9 - Sw = 0.04 m/m Step 13. Col. 13 - W = 0.6 m (2 ft) Step 14. Col. 14 - Determine spread, T, using Equation 6.2 or Chart 1. 0.375 T= Ø Qn} {KS 1x.67 S L0.5 }ø { Œ œ º ß 0.375 1.67 0.5 ø Ø T = Œ{(0.095)(0.016)} (0.376)(0.04) (0.03) œ º ß T = 1.83 m (6.0 ft) (less than allowable, therefore proceed to next step) Col. 122 - Determine depth at curb, d, using Equation 6.3.

{

}

d = TS x = (1.83)(0.04)= 0.073 m (0.24 ft) (less than actual curb height, therefore proceed to o next step) Step 15. Col 15 - W T = 0.6 1.83 = 0.333 Step 16. Col. 16 - Select a P 50 x 100 grate measuring 0.6 m wide by 0.9 m long (2 ft by 3 ftt) Step 17. Col 17 - Calculate intercepted flow, Qi . 2.67

Eo = 1 - (1 - W T )

2.67

Eo = 1 - (1 - 0.33)

{Equation 6.18 or Chart 2} = 0.66

V = 0.752 nS L0.5 S x0.67 T 0.67 {Equation 6.15 or Chart 4} 0.5

V = 0.752 (0.016)(0.03)

0.67

0.67

(0.04) (1.83)

V = 1.41 m/s (4.6 ft/s) R f = 1.0 {Chart 5} {Equation 6.21 or Chart 6} Rs = 1 Ø 1 + 0.0828V 1.8 ) (S x L2.3 )ø œ Œ ß º ( 1.8 2.3 Ø Rs = 1 Œ1 + (0.0828)(1.41) (0.04)(0.9) øœ º ß Rs = 0.17

{


}{

}

6-263


Figure 6-20: Inlet Spacing Computation Sheet

6-264


Pavement Drainage

ø {Equation 6.23} Qi = Q Ø Œ œ ºR f Eo + Rs (1 - Eo )ß Ø1.0)(0.66)+ (0.17)(1 - 0.66)ø Qi = (0.095)( º ß Qi = 0.068 m3 /s (2.4 cfs) Step 18. Col. 18 - Qb = Q - Qi = 0.095 - 0.068 Qb = 0.027 m3 /s (1.0 cfs) Step19. Col.1 - Inlet # 41 Col. 2 - Stationn 18+90 Col. 3 - Drainage area = (11 10 m)(13 m) = 1430 m 2 = 0.14 ha (0.35 ac) Col. 4 - Runoff coefficient, C = 0.73 Step p 20. Col. 5 - V = 1.1 m/s (3.5 ft/s) {Step 8} ø tc = L [60V ]= 110 Ø º(60)(1.1)ß= 2 min (Use 5 minutes maximum) Step 21. Col. 6 - I = 180 mm/hr Step 22. Col. 7 - Q = CIA K c Q = (0.73)(180)(0.14) (360)= 0.051 m3 /s (1.8 cfs) Step 23. Col. 11 - Col. 11 = Col. 10 + Col. 7 = 0.027 + 0.051 = 0.078 m3 /s (2.8 cfs) Step 24. Col. 14 - T = 1.50 m (4.9 ft) {Equation 7.2 or Charrt 1} T < T allowable Col. 12 - d = 0.06 m (0.20 ft) d < curb height Since thee actual spread is less than the allowable spread, a larger invert spacing could be used heere. However, in this case, maintenance considerations limit the spacing to 110 m (360 ft). Step 25. Col. 16 - Select P 50 x 1000 grate 0.6 m wide by 0.9 m long (2 ft by 3 ft) Step 26. Col. 17 - Qi = 0.040 m3 /s (1.4 cfs){Step 17} Step 27. Col. 18 - Q b = Q - Qi Col. 18 = Col. 11 - Col. 17 Col. 18 = 0.078 - 0.040 = 0.38 m3 /s (1.3 cfs) Step 28. Repeat Steps 19 through 27 forr each additional inlet. (2 ft by 3 ft)


6-265

Drainage Inlet Design For inlet spacing in areas with changing grades, the spacing will vary as the grade changes. If the grade becomes flatter, inlets may be spaced at closer intervals because the spread will exceed the allowable. Conversely, for an increase in slope, the inlet spacing will become longer because of increased capacity in the gutter sections. Additionally, individual transportation agencies may have limitations for spacing due to maintenance constraints.

Flanking Inlets d = Depth at Curb at Design Spread

Flanking Inlet

d=0.06m (0.2ft) 0.04m (0.12ft) Flanking Inlet Low Point Inlet 11.0m (38ft)

11.0m (38ft)

Figure 6-21: Example of Flanking Inlet As discussed in the previous section, inlets should always be located at the low or sag points in the gutter profile. In addition, it is good engineering practice to place flanking inlets on each side of the low point inlet when in a depressed area that has no outlet except through the system. This is illustrated in Figure 6-21. The purpose of the flanking inlets is to act in relief of the inlet at the low point if it should become clogged or if the design spread is exceeded. Flanking inlets can be located so they will function before water spread exceeds the allowable spread at the sump location. The flanking inlets should be located so that they will receive all of the flow when the primary inlet at the bottom of the sag is clogged. They should do this without exceeding the allowable spread at the bottom of the sag. If the flanking inlets are the same dimension as the primary inlet, they will each intercept one-half the design flow when they are located so that the depth of ponding at the flanking inlets is 63 percent of the depth of ponding at the low point. If the flanker inlets are not the same size as the primary inlet, it will be necessary to either develop a new factor or do a trial and error solution using assumed depths with the weir equation to determine the capacity of the flanker inlet at the given depths. Table 6-8 shows the spacing required for various depth at curb criteria and vertical curve lengths defined by K = L / (G2 – G1), where L is the length of the vertical curve in meters and G1 and G2 are the approach grades. The AASHTO policy on geometrics specifies maximum K values for various design speeds and a maximum K of 50 considering drainage. The use of table 6-8 is illustrated in Example 6-16.

6-266


Pavement Drainage Table 6-8: Distance to Flanking Inlets in Sag Vertical Curve using Depth at Curb Criteria d(m)

4

8

11

15

20

25

30

37

43

50

0.01

2.8

4.0

4.7

5.5

6.3

7.1

7.7

8.6

9.3

10.0

0.02

4.0

5.7

6.6

7.7

8.9

10.0

11.0

12.2

13.1

14.1

0.03

4.9

7.0

8.2

9.6

11.0

12.3

13.5

15.0

16.2

17.5

0.06

7.0

9.9

11.6

13.5

15.6

17.5

19.1

12.2

22.9

24.7

0.09

8.6

12.1

14.2

16.6

19.1

21.4

23.4

26.0

28.0

30.2

0.12

9.9

14.0

16.4

19.1

22.1

24.7

27.1

30.0

32.4

34.9

0.15

11.0

15.6

18.3

21.4

24.7

27.6

30.2

33.6

36.2

39.0

0.18

12.1

17.1

20.1

23.4

27.1

30.2

33.1

36.8

39.7

42.8

0.21

13.1

18.5

21.7

25.3

29.2

32.7

35.8

39.7

42.8

46.2

0.24

14.0

19.8

23.2

27.1

31.2

34.9

38.3

42.5

45.8

49.4

• 1. x = (200dK) 0.5, where x = distance from sag point • 2. d = depth at curb in meters (does not include sump depth) • 3. drainage maximum K = 50


6-267


Given: A 150 m (L) sag vertical curve at an underpass on a 4-lane divided highway with begin and end slopes of -2.5% and +2.5% respectively. The spread at design n Q is not to exceed the shoulder width of 3.0 m (9.8 ft).. S x = 0.02 Find: The location of the flanking inlets if located to function in relief of the inlet at thee low point when the inlet at the low point is clogged. Sollution: Step 1. Find the rate of vertical curvature, K. K = L (Sbegin - Send ) K = 150 m (- 2.59 - 2.59) K = 30 m Step 2. Determine depth at design spread. d = S x T = (0.02)(3.0) d = 0.06 m (0.2 ft) Step 3. Determine the depth for flanker locations. d = 0.06(0.63) = 0.04 m (0.12 ft) Step 4. For use with Table 7-7; d = 0.06 - 0.04 = 0.02 m (0.06 ft) Inlet spacing = 11.0 m (36 ft) from the sag point. Example problem solutions in “Interception Capacity of Inlets in Sag Locations” on page 6-243 illustrate the total interception capacity of inlets in sag locations. Except where inlets become clogged, spread on low gradient approaches to the low point is a more stringent criterion for design than the interception capacity of the sag inlet. AASHTO recommends that a gradient of 0.3 percent be maintained within 15 m (50 ft) of the level point in order to provide for adequate drainage. It is considered advisable to use spread on the pavement at a gradient comparable to that recommended by the AASHTO Committee on Design to evaluate the location and design of inlets upgrade of sag vertical curves. Standard inlet locations may need to be adjusted to avoid excessive spread in the sag curve. Inlets may be needed between the flankers and the ends of the curves also. For major sag points, the flanking inlets are added as a safety factor, and are not considered as intercepting flow to reduce the bypass flow to the sag point. They are installed to assist the sag point inlet in the event of clogging.

6-268


Pavement Drainage

6.4.7

Median, Embankment, and Bridge Inlets Flow in median and roadside ditches is discussed briefly in “Bentley FlowMaster Theory” on page 5-131 and in Hydraulic Engineering Circular No. 15 and Hydraulic Design Series No. 4. It is sometimes necessary to place inlets in medians at intervals to remove water that could cause erosion. Inlets are sometimes used in roadside ditches at the intersection of cut and fill slopes to prevent erosion downstream of cut sections. Where adequate vegetative cover can be established on embankment slopes to prevent erosion, it is preferable to allow storm water to discharge down the slope with as little concentration of flow as practicable. Where storm water must be collected with curbs or swales, inlets are used to receive the water and discharge it through chutes, sod or riprap swales, or pipe downdrains. Bridge deck drainage is similar to roadway drainage and deck drainage inlets are similar in purpose to roadway inlets. Bridge deck drainage is discussed in greater detail in Design of Bridge Deck Drainage, published in 1993 by the Federal Highway Administration.

Median and Roadside Ditch Inlets Median and roadside ditches may be drained by drop inlets similar to those used for pavement drainage, by pipe culverts under one roadway, or by cross drainage culverts which are not continuous across the median. Figure 6-22 illustrates a traffic-safe median inlet. Inlets, pipes, and discontinuous cross drainage culverts should be designed so as not to detract from a safe roadside. Drop inlets should be flush with the ditch bottom and traffic-safe bar grates should be placed on the ends of pipes used to drain medians that would be a hazard to errant vehicles, although this may cause a plugging potential. Cross drainage structures should be continuous across the median unless the median width makes this impractical. Ditches tend to erode at drop inlets; paving around the inlets helps to prevent erosion and may increase the interception capacity of the inlet marginally by acceleration of the flow. Pipe drains for medians operate as culverts and generally require more water depth to intercept median flow than drop inlets. No test results are available on which to base design procedures for estimating the effects of placing grates on culvert inlets. However, little effect is expected. The interception capacity of drop inlets in median ditches on continuous grades can be estimated by use of Charts 14 and 15 to estimate flow depth and the ratio of frontal flow to total flow in the ditch.


6-269


1.2m (typ)

Flo w

A

1:8

1:8 ) (typ (typ ) Embankment Material

Slope Inlet

Section A-A

A B 0.15m to .30m

B

Section B-B

Figure 6-22: Median Drop Inlet Chart 14 is the solution to the Manning equation for channels of various side slopes. The Manning equation for open channels is:

Q=

Where

KM AR 0.67 S L0.5 n

(6.39)

Q

=

Discharge rate (m3/sec., ft3/sec.)

KM

=


n

=

Hydraulic resistance variable

A

=

Cross-sectional area of flow (m2, ft2)

R

=

Hydraulic radius—area/wetted perimeter (m, ft)

SL

=

Bed slope (m/m, ft/ft)

For the trapezoidal channel cross section shown on Chart 14, the Manning equation becomes: 0.67

KM B + zd 2 2 Q= ( B + zd ) n ŁB + 2d z 2 + 1 ł

6-270

S L0.5 (6.40)


Pavement Drainage

Where

B

=

Bottom width (m, ft)

z

=

Horizontal distance of side slope to a rise of 1 m (ft) vertical (m, ft)

Equation 6.40 is a trial and error solution to Chart 14. Chart 15 is the ratio of frontal flow to total flow in a trapezoidal channel. This is expressed as:

Eo = W (B + dz )

(6.41)

Charts 5 and 6 are used to estimate the ratios of frontal and side flow intercepted by the grate to total flow. Small dikes downstream of drop inlets (Figure 6-22) can be provided to impede bypass flow in an attempt to cause complete interception of the approach flow. The dikes usually need not be more than a few inches high and should have traffic safe slopes. The height of dike required for complete interception on continuous grades or the depth of ponding in sag vertical curves can be computed by use of Chart 9. The effective perimeter of a grate in an open channel with a dike should be taken as 2(L + W), since one side of the grate is not adjacent to a curb. Example 6-17 illustrates the use of Charts 14 and 15 for drop inlets in ditches on continuous grade. EXAMPLE 6-17

Given: A median ditch with the following characteristiccs: B = 1.2 m (3.9 ft) n = 0.03 z=6 S = 0.02 The flow in the median ditch is to be intercepteed by a drop inlet with a 0.6 m by 0.6 m (2 ft by 2 ft) P-50 parallel bar grate; there is no dike downstrream of the inlet.


6-271


Q = 0.28 m3 /s (9.9 cfs) Find: The intercepted and bypassed flows (Qi and Q b ) Solution: Step 1. Compute the ratio of frontal to total flow in trapezoidal channnel. Qn = (0.28)(0.03) Qn = 0.0084 m3 /s (0.30 cfs) d B = 0.12

{Chart 14}

d = (B )(d B )= (0.12)(1.20)= 0.14 m (0.46 ft) Eo = W (B + dz )

{Equation 7.38 or Chart 15}

ø Eo = (0.6) Ø º1.2 + (0..14)(6)ß= 0.30 Step 2. Compute frontal flow efficieency V=Q A Ø6)(0.14)+ 1.2ø A = (0.14)( º ß 2 2 A = 0.29 m (3.1 ft ) V = (0.28) (0.29)= 0.97 m/s (3.2 ft/s) R f = 1.0

{Chart 5}

Step 3. Compute side flow efficiency. Since the ditch bottoom is wider than the grate and has no cross slope, use the least cross slope available on Chart 6 or use Equation 6.21 to solve for R s . Rs = 1 Ø 1 + 0.0 0828V 1.8 ) S x L2.3 ø {Equation 6.21 or Chart 6} Œ œ º ( ß 1.8 2.3 Ø Rs = 1 Œ1 + (0.0828)(0.97) (0.01)(0.6) øœ= 0.04 º ß Step 4. Compute total efficiency.

{

}

- Eo ) E = Eo R f + Rs (1E = (0.30)(1.0)+ (0.04)(1 - 0.30)= 0.33 Step 5. Compute interception and bypass flow. Qi = EQ = (0.33)(0.28) Qi = 0.1 m3 /s (3.5 cfs) Qb = Q - Qi = (0.28)- (0.1) Qb = 0.18 m3 /s (6.4 cfs)

6-272


Pavement Drainage In the preceding example, a P-50 inlet would intercept about 30 percent of the flow in a 1.2 m (4 ft) bottom ditch on continuous grade. For grate widths equal to the bottom width of the ditch, use Chart 6 by substituting ditch side slopes for values of Sx, as illustrated in Example 6-18. EXAMPLE 6-18

Given: A median ditch with the following characteristiccs: Q = 0.28 m3 /s (9.9 cfs) B = 0.6 m (2 ft) W = 0.6 m (2 ft) n = 0.03 z=6 Sx = 1 6 = 0.17 S = 0.03 The flow in the median ditch is to be intercepted by a drop inlet with a 0.6 m by 0.6 m (2 ft by 2 ft) P-50 parallel bar grate; there is no dike downstream of the inlet. Find: The intercepted and bypassed flows (Qi and Q b ). Solution: Step 1. Compute ratio of frontal flow to total flow in trapezoidal channell. Qn = (0.28)(0.03) Qn = 0.0084 m3 /s (0.30 cfs) d B = 0.25 {Chart 14} d = (0.25)(0.6)= 0.15 m (0.49 ft) Eo = W (B + dz )

{Equation 6.41 or Chart15}

ø Eo = (0.6) Ø º0.6 + (0.15)(6)ß= 0.40 Step 2. Compute frontal flow efficiency V= Q A Ø6)(0.15)+0.6ø A= (0.15)( º ß A=0.23 m 2 (2.42 ft 2 )


6-273


V= (0.28) (0.23)=1.22 m/s (4.0 ft/s) R f =1.0

{Chart 5}

Step 3. Compute side flow efficiency Rs = 1 Ø {Equation 6.21 or Chart 6} 1 + 0.0828V 1.8 ) (S x L2.3 )ø Œ œ º ( ß 1.8 2.3 Ø Rs = 1 Œ1 + (0.0828)(1.22) (0.17)(0.6) øœ º ß Rs = 0.30

{

}

Step 4. Compute total efficiency. E = Eo R f + Rs (1 - Eo ) 0)+ (0.30)(1 - 0.40)= 0.58 E = (0.40)(1.0 Step 5. Compute interception and bypass flow. Qi = EQ = (0.58)(0.28) Qi = 0.16 m3 /s (5.7 cfs) Qb = Q - Qi = 0.28 - 0.16 Qb = 0.12 m3 /s (4.2 cfs) The height of dike downstream of a drop inlet required for total interception is illustrated by Example 6-19. EXAMPLE 6-19

Given: Data from Example 6-18 Find: The required heiight of a berm to be located downstream of the grate inlett to cause total interception of the ditch flow. Soluttion: P = 2 (L + W ) P = 2 (0.6 + 0.6) ø0.67 D= Ø ºQi (Cw P )ß {Equation 6.28 or Chart 9} ø0.67 = 0.17 m (0.55 ft) 0 . 28 1 . 66 2 . 4 d= Ø ( ) ( )( ) { } œ Œ º ß A dike will need to have a minimum height of 0.16 m (0.5 ft) for total interception. Due to the initial velocity of the water which may provide adequate momentum to carry the flow over the dike, an additional 0.15 m (0.5 ft) may be added to the height of the dike to insure complete interception of the flow.

6-274


Pavement Drainage

Embankment Inlets Drainage inlets are often needed to collect runoff from pavements in order to prevent erosion of fill slopes or to intercept water upgrade or downgrade of bridges. Inlets used at these locations differ from other pavement drainage inlets in three respects. First, the economies which can be achieved by system design are often not possible because a series of inlets is not used; second, total or near total interception is sometimes necessary in order to limit the bypass flow from running onto a bridge deck; and third, a closed storm drainage system is often not available to dispose of the intercepted flow, and the means for disposal must be provided at each inlet. Intercepted flow is usually discharged into open chutes or pipe downdrains, which terminate at the toe of the fill slope.

a. Perspective

Inlet

Outlet Pipe b. Section

Figure 6-23: Embankment Inlet and Downdrain


6-275

Grate Type Selection Considerations Example problem solutions in other sections of this circular illustrate by inference the difficulty in providing for near total interception on grade. Grate inlets intercept little more than the flow conveyed by the gutter width occupied by the grate. Combination curb-opening and grate inlets can be designed to intercept total flow if the length of curb opening upstream of the grate is sufficient to reduce spread in the gutter to the width of the grate used. Depressing the curb opening would significantly reduce the length of inlet required. Perhaps the most practical inlets or procedure for use where near total interception is necessary are sweeper inlets, increase in grate width, and slotted inlets of sufficient length to intercept 85-100 percent of the gutter flow. Design charts and procedures in “Interception Capacity of Inlets on Grade” on page 6-227 are applicable to the design of inlets on embankments. Figure 6-23 illustrates a combination inlet and downdrain. Downdrains or chutes used to convey intercepted flow from inlets to the toe of the fill slope may be open or closed chutes. Pipe downdrains are preferable because the flow is confined and cannot cause erosion along the sides. Pipes can be covered to reduce or eliminate interference with maintenance operations on the fill slopes. Open chutes are often damaged by erosion from water splashing over the sides of the chute due to oscillation in the flow and from spill over the sides at bends in the chute. Erosion at the ends of downdrains or chutes can be a problem if not anticipated. The end of the device may be placed low enough to prevent damage by undercutting due to erosion. Well-graded gravel or rock can be used to control the potential for erosion at the outlet of the structure. However, some transportation agencies install an elbow or a tee at the end of the downdrains to re-direct the flow and prevent erosion. See HEC-14) for additional information on energy dissipator designs.

6.5

Grate Type Selection Considerations Grate type selection should consider such factors as hydraulic efficiency, debris handling characteristics, pedestrian and bicycle safety, and loading conditions. Relative costs will also influence grate type selection. Charts 5, 6, and 9 illustrate the relative hydraulic efficiencies of the various grate types discussed here. The parallel bar grate (P-50) is hydraulically superior to all others but is not considered bicycle safe. The curved vane and the P-30 grates have good hydraulic characteristics with high velocity flows. The other grates tested are hydraulically effective at lower velocities. Debris-handling capabilities of various grates are reflected in Table 6-5. The table shows a clear difference in efficiency between the grates with the 83 mm (3-1/4 inch) longitudinal bar spacing and those with smaller spacings. The efficiencies shown in the table are suitable for comparisons between the grate designs tested, but should not be taken as an indication of field performance since the testing procedure used did not simulate actual field conditions. Some local transportation agencies have developed factors for use of debris handling characteristics with specific inlet configurations.

6-276


Pavement Drainage Table 6-9 ranks the grates according to relative bicycle and pedestrian safety. The bicycle safety ratings were based on a subjective test program as described in Hydraulic and Safety Characteristics of selected Grate Inlets on Continuous Grades volumes 1 and 2, published by the FHWA in June 1977 and April 1978, respectively. However, all the grates are considered bicycle and pedestrian safe except the P-50. Grate loading conditions must also be considered when determining an appropriate grate type. Grates in traffic areas must be able to withstand traffic loads; conversely, grates draining yard areas do not generally need to be as rigid. Table 6-9: Ranking with Respect to Bicycle and Pedestrian Safety


Rank

Grate Style

1

P-50x100

2

Reticuline

3

P-30

4

45-85 deg. Tilt Bar

5

45-60 deg. Tilt Bar

6

Curved Vane

7

30-85 deg. Tilt Bar

6-277

Grate Type Selection Considerations

6-278


Chapter

7

HEC 22 Charts

Chart 1A (S.I.) and 1B (U.S. customary)—Flow in triangular gutter sections Chart 2A (S.I.) and 2B (U.S. customary)—Ratio of frontal flow to total gutter flow Chart 3A (S.I.) and 3B (U.S. customary)—Conveyance in circular channels Chart 4A (S.I.) and 4B (U.S. customary)—Velocity in triangular gutter sections Chart 5A (S.I.) and 5B (U.S. customary)—Grate inlet frontal flow interception efficiency Chart 6A (S.I.) and 6B (U.S. customary)—Grate inlet side flow interception capacity Chart 7A (S.I.) and 7B (U.S. customary)—Curb-opening and slotted drain inlet interception capacity Chart 8A (S.I.) and 8B (U.S. customary)—Curb-opening and slotted drain inlet interception capacity. Chart 9A (S.I.) and 9B (U.S. customary)—Grate inlet capacity in sump conditions Chart 10A (S.I.) and 10B (U.S. customary)—Depressed curb opening inlet in sump locations Chart 11A (S.I.) and 11B (U.S. customary)—Curb-opening inlet in sump locations Chart 12A (S.I.) and 12B (U.S. customary)—Curb-opening inlet orifice capacity for inclined and vertical orifice throats Chart 13A (S.I.) and 13B (U.S. customary)—Slotted drain inlet capacity in sump locations Chart 14A (S.I.) and 14B (U.S. customary)—Solution of Manning’s equation for channels of various side slopes


7-279

Chart 15A (S.I.) and 15B (U.S. customary)—Ratio of frontal flow to total flow in a trapezoidal channel

7-280


HEC 22 Charts


7-281

7-282


HEC 22 Charts


7-283

7-284


HEC 22 Charts


7-285

7-286


HEC 22 Charts


7-287

7-288


HEC 22 Charts


7-289

7-290


HEC 22 Charts


7-291

7-292


HEC 22 Charts


7-293

7-294


HEC 22 Charts


7-295

7-296


HEC 22 Charts


7-297

7-298


HEC 22 Charts


7-299

7-300


HEC 22 Charts


7-301

7-302


HEC 22 Charts


7-303

7-304


HEC 22 Charts


7-305

7-306


HEC 22 Charts


7-307

7-308


Chapter

8

Engineer’s Reference

This section includes:

8.1

•

“Energy Equation” on page 8-309

•

“Roughness Values—Manning’s Equation” on page 8-310

•

“Roughness Values—Kutter’s Equation” on page 8-312

•

“Roughness Values—Darcy-Weisbach (Colebrook-White) Equation” on page 8314

•

“Roughness Values—Hazen-Williams Formula” on page 8-315

Energy Equation The energy relationship between the downstream and upstream end of a pipe is:

V12 P1 V2 P + + z1 + hG = 2 + 2 + z2 + hL 2g g 2g g Where

V

=

Fluid velocity (m/sec.2, ft/sec.2)

g

=


P

=

Pressure (N/m.2, lb/ft2)

γ

=

Specific weight of fluid (N/m.3, lb/ft3)

z

=

Elevation at centroid (m, ft)

hG

=

Headgain, such as from a pump (m, ft)

hL

=

Combined headloss (m, ft)


(8.1)

8-309

Roughness Values—Manning’s Equation

8.2

Roughness Values—Manning’s Equation Commonly used roughness values for different materials are: Table 8-1: Manning’s Coefficients n for Closed Metal Conduits Channel Type and Description

Minimum

Normal

Maximum

Brass, smooth

0.009

0.010

0.013

Steel; Lockbar and welded

0.010

0.012

0.014

Steel; Riveted and spiral

0.013

0.016

0.017

Cast iron; Coated

0.010

0.013

0.014

Cast iron; Uncoated

0.011

0.014

0.016

Wrought iron; Black

0.012

0.014

0.015

Wrought iron; Galvanized

0.013

0.016

0.017

Corrugated metal; Subdrain

0.017

0.019

0.021

Corrugated metal; Storm Drain

0.021

0.024

0.030

Table 8-2: Manning’s Coefficients n for Closed Non-Metal Conduits

8-310

Channel Type and Description

Minimum

Normal

Maximum

Lucite

0.008

0.009

0.010

Glass

0.009

0.010

0.013

Cement; Neat, surface

0.010

0.011

0.013

Cement; Mortar

0.011

0.013

0.015

Concrete; Culvert, straight and free of debris

0.010

0.011

0.013

Concrete; Culvert with bends, connections, and some debris

0.011

0.013

0.014

Concrete; Finished

0.011

0.012

0.014


Engineer’s Reference Table 8-2: Manning’s Coefficients n for Closed Non-Metal Conduits Channel Type and Description

Minimum

Normal

Maximum

Concrete; Sewer with manholes, inlet, etc., straight

0.013

0.015

0.017

Concrete; Unfinished, steel form

0.012

0.013

0.014

Concrete; Unfinished, smooth wood form

0.012

0.014

0.016

Concrete; Unfinished, rough wood form

0.015

0.017

0.020

Wood; Stave

0.010

0.012

0.014

Wood; Laminated, treated

0.015

0.017

0.020

Clay; Common drainage tile

0.011

0.013

0.017

Clay; Vitrified sewer

0.011

0.014

0.017

Clay; Vitrified sewer with manholes, inlet, etc.

0.013

0.015

0.017

Clay; Vitrified subdrain with open joint

0.014

0.016

0.018

Brickwork; Glazed

0.011

0.013

0.015

Brickwork; Lined with cement mortar

0.012

0.013

0.016

Sanitary sewers coated with sewage slimes, with bends and connections

0.012

0.013

0.016

Paved invert, sewer, smooth bottom

0.016

0.019

0.020

Rubble masonry, cemented

0.018

0.025

0.030


8-311

Roughness Values—Kutter’s Equation

8.3

Roughness Values—Kutter’s Equation Table 8-3: Roughness Values—Kutter’s Equation Channel Type and Description

Minimum

Normal

Maximum

Brass, smooth

0.009

0.010

0.013

Steel; Lockbar and welded

0.010

0.012

0.014

Steel; Riveted and spiral

0.013

0.016

0.017

Cast iron; Coated

0.010

0.013

0.014

Cast iron; Uncoated

0.011

0.014

0.016

Wrought iron; Black

0.012

0.014

0.015

Wrought iron; Galvanized

0.013

0.016

0.017

Corrugated metal; Subdrain

0.017

0.019

0.021

Corrugated metal; Storm Drain

0.021

0.024

0.030

Table 8-4: Kutter’s Coefficients n for Closed Non-Metal Conduits

8-312

Channel Type and Description

Minimum

Normal

Maximum

Lucite

0.008

0.009

0.010

Glass

0.009

0.010

0.013

Cement; Neat, surface

0.010

0.011

0.013

Cement; Mortar

0.011

0.013

0.015

Concrete; Culvert, straight and free of debris

0.010

0.011

0.013

Concrete; Culvert with bends, connections, and some debris

0.011

0.013

0.014

Concrete; Finished

0.011

0.012

0.014

Concrete; Sewer with manholes, inlet, etc., straight

0.013

0.015

0.017


Engineer’s Reference Table 8-4: Kutter’s Coefficients n for Closed Non-Metal Conduits Channel Type and Description

Minimum

Normal

Maximum

Concrete; Unfinished, steel form

0.012

0.013

0.014

Concrete; Unfinished, smooth wood form

0.012

0.014

0.016

Concrete; Unfinished, rough wood form

0.015

0.017

0.020

Wood; Stave

0.010

0.012

0.014

Wood; Laminated, treated

0.015

0.017

0.020

Clay; Common drainage tile

0.011

0.013

0.017

Clay; Vitrified sewer

0.011

0.014

0.017

Clay; Vitrified sewer with manholes, inlet, etc.

0.013

0.015

0.017

Clay; Vitrified subdrain with open joint

0.014

0.016

0.018

Brickwork; Glazed

0.011

0.013

0.015

Brickwork; Lined with cement mortar

0.011

0.013

0.015

Sanitary sewers coated with sewage slimes, with bends and connections

0.012

0.013

0.016

Paved invert, sewer, smooth bottom

0.016

0.019

0.020

Rubble masonry, cemented

0.018

0.025

0.030


8-313

Roughness Values—Darcy-Weisbach (Colebrook-White) Equation

8.4

Roughness Values—Darcy-Weisbach (Colebrook-White) Equation Table 8-5: Darcy-Weisbach Roughness Heights k for Closed Conduits

8-314

Pipe Material

k (mm)

k (ft)

Glass, drawn brass, copper (new)

0.0015

0.000005

Seamless commercial steel (new)

0.004

0.000013

Commercial steel (enamel coated)

0.0048

0.000016

Commercial steel (new)

0.045

0.00015

Wrought iron (new)

0.045

0.00015

Asphalted cast iron (new)

0.12

0.0004

Galvanized iron

0.15

0.0005

Cast iron (new)

0.26

0.00085

Wood stave (new)

0.18 ~ 0.9

0.0006 ~ 0.003

Concrete (steel forms, smooth)

0.18

0.0006

Concrete (good joints, average)

0.36

0.0012

Concrete (rough, visible, form marks)

0.60

0.002

Riveted steel (new)

0.9 ~ 9.0

0.003 ~ 0.03

Corrugated metal

45

0.15


Engineer’s Reference

8.5

Roughness Values—Hazen-Williams Formula Table 8-6: Hazen-Williams Coefficients Pipe Material

C

Asbestos cement

140

Brass

130 – 140

Brick Sewer

100

Cast iron; New, unlined

130

Cast iron; 10 yr. old

107 – 113


89 – 100


75 – 90


64 – 83

Concrete or concrete lined; Steel forms

140

Concrete or concrete lined; Wood forms

120

Concrete or concrete lined; Centrifugally spun

135

Copper

130 – 140

Galvanized iron

120

Glass

140

Lead

130 – 140

Plastic

140 – 150

Steel; Coal tar enamel, lined

145 – 150

Steel; New, unlined

140 – 150


8-315

Roughness Values—Hazen-Williams Formula Table 8-6: Hazen-Williams Coefficients (Continued)

8-316

Pipe Material

C

Steel; Riveted

110

Tin

130

Vitrified clay (good condition)

110 – 140

Wood stave (average condition)

120


Index A AASHTO 171 about the software 34 active grate length 78, 86, 96 active grate weir length 75, 83, 92 actual flow depth 135 address See contacting Haestad Methods. 11 adjusted discharge coefficient 69 alphabetic 104 analysis menu 33 analysis toolbar 36 aspect ratio 99 attribute 107

B backwater analysis 140 bottom width 39, 45, 60, 82, 84, 97 boundary control depth 134 broad-crested weir 68, 146 bypass flow 77, 81, 85, 89, 95, 159

C calculation messages 39, 42, 45, 47, 49, 51, 55, 56, 59, 62, 65, 66, 67, 68, 69, 70, 71, 72, 73, 75, 78, 80, 82, 84, 86, 88, 90, 93 calculation option 96 carryover 159 cascade 33 categorized 104 centroid elevation 70, 71, 72 channel 38, 39, 42, 44, 48, 51, 52 channel slope 39, 41, 42, 44, 45, 47, 49, 51, 52, 54, 57, 59, 60, 62, 65, 97


channel worksheets 38 chart options 98, 114 charts: where to find them 171 Chézy 119 Chézy's 127 Chézy’s equation 127 Cipoletti weir 67 Cipolletti 144 circular channel 56 circular orifice 71 ClientCare 10 clogging 74, 77, 83, 85, 91, 95 close 31 close all 34 Colebatch 101 Colebrook 122 Colebrook-White 127 Colebrook-White equation 131 combination inlet in sag 90, 169 combination inlet on grade 163 combination inlet on grade worksheet 93 composite cross slope 162 composite gutter section 154 conjugate depth 59 constructed depth 52 constructed top width 52 contacting Haestad Methods email 11 fax 11 hours 10 mail 11 sales 9 technical support 10 telephone 11 contents 34, 106 continuity equation 118 continuously depressed gutter 155 contracted 142 copy 32

Index-303

D copy worksheet data 32 cox 102 create new project 28 create worksheet 28 crest breadth 68 crest elevation 65, 66, 67, 68, 69 crest length 65, 67, 68, 69 crest surface type 68 critical 40, 53, 86, 123, 135 critical depth 40, 43, 46, 52, 57, 60, 63, 86, 133, 135 critical elevation 50 critical flow 122, 132, 133 critical slope 40, 43, 46, 50, 52, 57, 60, 63, 86, 133, 134, 135 cross section 33, 99 cross-section 115 curb 79, 80, 92, 95 curb inlet 96 curb inlet in sag 165 curb inlet on grade 80 curb opening 162, 163 curb opening length 79, 80, 92, 95 curb throat type 79, 92 curves 98 cut 32

D Darcy-Weisbach 121, 127, 129, 131 Darcy-Weisbach formula 121 date 104 decimal point 103 default unit system for new project 104 define rating curve 98, 114 define rating table 97 delete worksheet 32 depth 48, 74, 77, 79, 81, 83, 87, 89, 92, 95, 105 detailed report 33 diameter 55, 57, 71 direct step 139 direct step method 139 direction 40, 43 Discharge 68 discharge 39, 41, 42, 44, 45, 47, 48, 49, 51, 52, 54, 55, 57, 59, 60, 62, 63, 65, 66, 67, 68, 69,

Index-304

70, 71, 72, 73, 76, 78, 80, 82, 84, 87, 88, 90, 93 discharge coefficient 65, 67, 69, 70, 71, 72 discharge coefficient weir 69 discharge full 58, 61, 63 display precision 103 distance 105 ditch 82, 84, 156 ditch inlet in sag 81 ditch inlet on grade 84 documentation 2 downstream depth 41, 44, 46, 50, 53, 58, 61, 64 downstream velocity 41, 44, 47, 51, 54, 59, 62, 64 drainage 171, 172 duplicate worksheet 32 dynamic help 34

E edit menu 32 edit section 48 editor 99 efficiency 76, 80, 84, 89, 94 EGL 126 elevation 99 elevation at 1 55 elevation at 2 55 elevation head 126, 151 elevation range 49 elliptical pipe 62 email 11 email address 11 end depth/rise 41, 44, 47, 51, 54, 59, 62, 64 end station 100 energy balance 138 energy equation 125, 150 energy grade 126 energy grade at 1 55 energy grade at 2 56 energy grade line 126 energy principle 124 engineer 104 engineering library 32 engineering library explorer 30 entrance controlled 141


F equal length inlets 169 equal side slopes 68 equivalent cross slope 81, 89, 96 error.log 10

F family of curves 98 fax 11 field 107 field id 97 file menu 31 filename 104 find 106 fixed point 103, 107 flexunits 33, 103 Flow 48 flow area 39, 43, 45, 48, 49, 52, 56, 57, 60, 63, 66, 67, 68, 69, 70, 71, 77, 81, 85, 89, 95, 105 flow depth 135 flow regime 132, 135 flow type 40, 53, 86 format 103, 104, 107 formatter 103 free surface flow 134 frequency 172 friction factor 40, 43, 46, 50, 53, 56, 58, 61, 63, 122 friction loss 127 friction method 48 friction slope 56 front flow 96 frontal flow 77, 156 frontal flow factor 77, 85, 96 frontwater analysis 141 Froude 122 Froude number 40, 43, 46, 50, 53, 58, 61, 63, 86

G gate 149 general 103, 108 generalized friction equation 117 generic orifice 72 generic weir 69


given downstream 41, 43, 46 given upstream 41, 43, 46 glossary 9 gradually varied flow 46, 53, 58, 61, 64, 105, 127, 141 gradually varied flow analysis 18 gradually varied profile 105 graph display options 98 Grate 94 grate 76, 82, 84, 91, 94, 163 grate flow option 96 grate flow ratio 78, 85, 96 grate inlet 96 grate inlet in sag 164 grate inlet on grade 159 grate length 74, 76, 82, 84, 91, 94 grate type 74, 76, 82, 85, 91, 94 grate width 74, 76, 82, 84, 91, 94 gutter 73, 76, 78, 80, 87, 88, 90, 93 gutter cross slope 48, 73, 76, 79, 80, 87, 88, 90, 93 gutter depression 48, 75, 77, 79, 81, 87, 89, 92, 95, 155, 158 gutter flow 152 gutter width 48, 73, 76, 78, 80, 87, 88, 90, 93 GVF profile 33 GVF profile table 33

H H3 135 Haestad Methods email addresses 11 Web site 11 Haestad.log 10 Hazen-Williams 120, 127 Hazen-Williams Formula 120, 132 head gains 125 headloss 41, 44, 47, 51, 54, 55, 59, 62, 64 headlosses 125 headwater elevation 65, 66, 67, 68, 69, 70, 71, 72 headwater height above centroid 71, 72 headwater height above crest 66, 67, 68, 70 HEC-12 171 HEC-22 152 height 60

Index-305

I help menu 34 help toolbar 37 HGL 126, 151 HGL convergence test 126 highway 171, 172 horizontal 165 horizontal throat 79, 92 horton’s 101 how do i? 34 hydraulic grade 126, 151 hydraulic grade at 1 56 hydraulic grade at 2 56 hydraulic grade line 126 hydraulic head 126 hydraulic jump 141 hydraulic jumps 139 hydraulically mild slope 134, 135 hydraulically steep slope 134, 135

I improved Lotter 102 inclined 165 inclined throat 79, 92 increment 97, 98 index 34 inlet 73, 75, 78, 80, 81, 84, 86, 88, 90, 91, 93, 94, 96 inlet capacity 152 inlets in sag 164 inlets on grade 158 installing for network deployment 5 installing on a single computer 4 installing the software 3 intercepted flow 77, 81, 85, 89, 95 invert elevation 105 irregular channel 99 irregular section editor 48

K kinematic viscosity 39, 42, 45, 49, 52, 55, 57, 60, 63 Kutter’s 119, 127 Kutter’s equation 128

Index-306

Kutter’s formula 119

L left-side slope 42, 45, 82, 84, 97 Length 81 length 41, 44, 47, 51, 53, 55, 59, 61, 64 length factor 81, 90, 96 load 104 local depression 74, 79, 81, 82, 87, 89, 91, 94, 158 local depression width 74, 79, 81, 82, 87, 89, 91, 94 log files 10 Lotter 102

M M3 135 mail 11 main window 28 Manning's equation 128 Manning’s 119, 127 Manning’s coefficient 100 Manning’s formula 119 Mannings coefficient 48, 76, 84, 88, 93 manual scale 99 material libraries 30 materials 30 maximum 97, 98 maximum discharge 58 median section 156 menus 31 messages 39, 42, 45, 47, 49, 51, 55, 56, 59, 62, 65, 66, 67, 68, 69, 70, 71, 72, 73, 75, 78, 80, 82, 84, 86, 88, 90, 93 mild 135 mild-1 135 minimize all 33 minimum 2, 97, 98 system requirements 2, 3 mixed flow profiles 139 multiple page view 106


N

N next page 106 non-sharp-crested 141 normal depth 39, 42, 45, 50, 52, 57, 60, 62, 97, 133, 134, 135 normal depth/rise 41, 44, 47, 51, 54, 59, 62, 64 normal flow 132 notch angle 66 notes 39, 42, 45, 47, 49, 51, 55, 56, 59, 62, 65, 66, 67, 68, 69, 70, 71, 72, 73, 75, 78, 80, 82, 84, 86, 88, 90, 93, 104 number 103, 108 number of contractions 65 number of steps 41, 44, 47, 51, 54, 59, 61, 64

O open 31 open channel weighting methods 100 open existing project 28 open grate area 75, 83, 92 open slot area 88 opening area 72 opening height 70, 79, 92 opening width 70 optimize 126 options 49, 96, 99, 107 orifice 70, 71, 72 orifice coefficients 149 orifice flow 165, 167, 169 overtopping 147

P parabolic channel 51 parameter 103 paste 32 pavement 171 pavement drainage 152 Pavlovskii’s 100 percent full 57, 60, 63 performance curves 114 piezometer 151 pipe 55, 56, 59, 62


pitot tube 126, 151 plot 98 power 103 precision 107 pressure at 1 55 pressure at 2 55 pressure flow 132, 133 pressure head 126, 151 pressure pipe 150 pressure pipe channel 55 preview 106 previous page 106 print 31, 106 print preview 31, 97, 98, 105, 106 printing reports 115 prismatic 133 profile 41, 44, 47, 51, 54, 59, 62, 64 profile classification 41, 134, 135 profile description 41, 43, 44, 46, 47, 50, 51, 54, 58, 59, 61, 62, 63, 64 project 14, 28, 31 project components 28 project explorer 28, 32 project file 104 project filename 104 project files 29 project menu 32 Projectname.fm8 29 Projectname.fm8.mdb 30 properties 33, 104

R rapidly varied flow 139 rating curve 33, 98 rating curves 113, 114 rating table 33, 97 recent projects 31 rectangular 142 rectangular orifice 70 rectangular weir 65 rectangular worksheet 39 redo 32 report title 99, 115 reporting 21 reports

Index-307

S about worksheets 115 printing 115 reset defaults SI 104 reset defaults US 104 results 21 Reynolds number 40, 43, 46, 50, 53, 56, 58, 61, 63, 121 right-side slope 42, 45, 82, 84, 97 rise 62 Road 79 road cross slope 48, 73, 76, 79, 80, 87, 88, 90, 93 roughness coefficient 39, 42, 45, 49, 52, 55, 57, 60, 62, 80, 97, 128 roughness method 100 runoff 172

S S3 135 sales 9 save 31 save all 31 save as 31 scientific 103, 107 sealing conditions 139 search 34 section 47 section geometry 99 section plot 100 segment roughness 100 SentinelLM 3 installing 6 settings 106 sharp-crested 141 sharp-crested V-notched weirs 144 sharp-crested weir 141, 145 SI 103 side flow 96 side flow factor 77, 85, 96 single curve 98 single page view 106 slope 48, 76, 80, 84, 88, 93, 134 slope classification 134, 135 slope full 58, 61, 63 slot 87, 89 slot inlet in sag 168

Index-308

slot length 87, 89 slot width 87 slotted-drain inlet in sag 86 slotted-drain inlet on grade 88 slotted-inlet on grade 163 sluice gate 149 software updates 34 solve for 48 span 63 specific energy 40, 43, 46, 50, 53, 57, 61, 63, 86, 105, 122 specific weight 55 splash over velocity 77, 85, 95 spread 48, 73, 77, 78, 81, 82, 87, 89, 90, 95 standard step 127, 139 standard step method 139 standard toolbar 35 start station 100 station 99 status bar 32 steep 135 subcritical 40, 53, 86, 123, 135 subcritical flow 132, 134 submerged 145 submergence correction 147 submergence factor 69 suggestions 11 supercritical 40, 53, 86, 123, 141 supercritical flow 132, 134 support 10 addresses 11 hours 10 suppressed 142 surcharging conditions 139 Swamee and Jain equation 131 sweeper inlet 170 system requirements 2

T tabular 105 tabular report 106 tabular reports 33 tailwater condition 134 tailwater elevation 65, 66, 67, 68, 70, 71, 72 tailwater height above centroid 71, 72


U tailwater height above crest 66, 67, 68, 69 technical support 10 TeeChart editor 98 throat 79, 92 throat-incline angle 79, 92 tile horizontally 33 tile vertically 33 toolbars 32, 35 top width 40, 43, 46, 49, 52, 57, 60, 63, 66, 67, 68, 69, 70, 83, 85 total depression 75, 77, 79, 81, 88, 89, 92, 95 total interception length 81, 90, 96 transition flow 168 transitional flow 165, 169 tutorials 13

U U.S. customary 103 undo 32 uniform flow 45, 49, 52, 57, 62, 73, 117, 132, 133 uniform gutter cross slope 152 uninstalling 8 unit 103, 107 updates 34 upstream depth 41, 44, 47, 50, 53, 58, 61, 64 upstream velocity 41, 44, 47, 51, 54, 59, 62, 65 using the software 34

W water surface elevation 49 Web site 11 weighted roughness 49 weir 65, 66, 67, 68, 69, 141 weir flow 165, 166, 168 welcome 28 welcome dialog box 34 wetted perimeter 40, 43, 45, 49, 52, 56, 57, 60, 63, 66, 67, 68, 69, 70, 83, 85, 105 What’s New 1 where to find charts 171 window menu 33 worksheet 13, 28, 31 workshops 11 workspace 28

Z zone 1 135 zone 2 135 zone 3 135 zone classification 134, 135 zoom 106 zoom in 106 zoom out 106

V varying 98 velocity 40, 43, 46, 48, 50, 53, 56, 57, 60, 63, 66, 67, 68, 69, 70, 71, 72, 77, 81, 85, 89, 95, 105 velocity head 40, 43, 46, 50, 53, 56, 57, 60, 63, 86, 126, 151 vertical 165 vertical throat 79, 92 view menu 32 V-notch weir 66 v-notch weir coefficient 66 vs 98


Index-309

Z

Index-310


Flow Master User's Guide

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