Final Detailed Design Report - Musita _ Majanji Road

GOVERNMENT OF UGANDA UGANDA NATIONAL ROADS AUTHORITY AUTHORITY

CONSULTANCY SERVICES FOR FEASIBILITY STUDY, DETAILED ENGINEERING DESIGN, TENDER ASSISTANCE AND PROJECT MANAGEMENT FOR UPGRADING OF ROADS TO BITUMINOUS STANDARDS

LOT E

FINAL

DETAILED DESIGN REPORT PKG 1 ROAD E1.1/E1.2 MUSITA-LUMINO/BUSIA-MAJANJI AUGUST 2012

IN ASSOCIATION WITH

Project Name:

Feasibilit Feasibility y Study, Detail Detailed ed Design, Design, Tender Assist Assistance ance and Project Managem Management for Upgrading of Roads to Bituminous Standards

Project Number:

5116004

Report for:

FINAL DETAILED DESIGN REPORT

PREPARATION, REVIEW AND AUTHORISATION Revision Re vision #

Date Da te

31 Aug 2012

1

Prepared Pre pared by

Nuruddin Wajihi/Michael Ogola/Edward Byaruhanga

Reviewed Re viewed by

Various

Approved for Issue by

Nuruddin Wajihi

ISSUE REGISTER Distribution List

Date Issued

Number of Copies

UNRA

31-08-2012

5

SMEC staff: Project Manager

31-08-2012

1

Client:

As Associate iates s: NEWPLAN Office Library (SMEC office location): SMEC SMEC Project File: K ampala

31-08-2012

1

SMEC COMPANY DETAILS SMEC INTERNATIONAL PTY LIMITED Kipr o Centre. 3rd 3rd Floor , Sport Sport s Road, Westlands Westlands , Nairobi Nairobi Tel:

+254 20 4441541/2

Fax:

+254 20 441543

Email:

[email protected] [email protected]

www.smec.com The information within this document is and shall remain the property of SMEC INTERNATIONAL PTY LTD.

Project Name:

Feasibilit Feasibility y Study, Detail Detailed ed Design, Design, Tender Assist Assistance ance and Project Managem Management for Upgrading of Roads to Bituminous Standards

Project Number:

5116004

Report for:

FINAL DETAILED DESIGN REPORT

PREPARATION, REVIEW AND AUTHORISATION Revision Re vision #

Date Da te

31 Aug 2012

1

Prepared Pre pared by

Nuruddin Wajihi/Michael Ogola/Edward Byaruhanga

Reviewed Re viewed by

Various

Approved for Issue by

Nuruddin Wajihi

ISSUE REGISTER Distribution List

Date Issued

Number of Copies

UNRA

31-08-2012

5

SMEC staff: Project Manager

31-08-2012

1

Client:

As Associate iates s: NEWPLAN Office Library (SMEC office location): SMEC SMEC Project File: K ampala

31-08-2012

1

SMEC COMPANY DETAILS SMEC INTERNATIONAL PTY LIMITED Kipr o Centre. 3rd 3rd Floor , Sport Sport s Road, Westlands Westlands , Nairobi Nairobi Tel:

+254 20 4441541/2

Fax:

+254 20 441543

Email:

[email protected] [email protected]

www.smec.com The information within this document is and shall remain the property of SMEC INTERNATIONAL PTY LTD.

Detailed Detailed Desi Design gn Repo Report rt (FINAL FINAL)) f o r FEASIBILITY FEASIB ILITY STUDY, STUDY, DETA DETA ILED IL ED ENGINEERING DESIGN, TENDER ASSISTA A SSISTANCE NCE AND A ND PROJECT PROJ ECT MANAGEME MANA GEMENT NT FOR UPGRADING ROADS TO BITU B ITUMIN MINOUS OUS STANDA STANDARDS RDS – LOT L OT E PACKAGE PACKA GE 1 : ROAD E1.1/E1.2 MUSITA-LUMINO/BUSIA-MAJANJI ROAD

For: UGANDA NATIO NA TIONAL NAL ROADS AUTH A UTHORI ORITY TY AUGUST A UGUST 2012

| FINAL FINAL Detailed Design Report_Rev.1-AUG.2012 Report_Rev.1-AUG.2012 |

KUMI BUKUNGU

PACKAGE – 4

PACKAGE – 2A

NAMAGUMBA-BUDADIRINALUGUGU

TIRINYI-PALLISA/ PALLISA-KUMI

NALUGUGU

PACKAGE – 5

PACKAGE– 2B

KAMULI - BUKUNGU PALLISA

PALLISA-KAMONKOLI

BUDADIRI

NAMAGUMBA

KAMONKOLI BUMBOBI TIRINYI

KAMULI

PACKAGE – 3

BUMBOBI-BUBULOLWAKHAKHA BUBULO LWAKHAKHA

MUSITA

BUSIA

PACKAGE – 1

MUSITA-LUMINO/ BUSIA-MAJANJI

LUMINO

MAJANJI

LOCATION OF LOT E ROADS

TABLE OF CONTENTS EXECUTIVE SUMMARY

ES-1

E1. Introduction

ES-1

E2. Economic Evaluation

ES-2

E3. Topographical Survey

ES-2

E4. Traffic Surveys

ES-3

E5. Traffic Growth and Projected Traffic

ES-3

E6. Axle Load Survey

ES-4

E7. Pavement Design

ES-5

E8. Materials Investigation

ES-6

E9. Hydrology

ES-7

1

E10. Drainage Design

ES-10

E11. Geometric Design

ES-12

INTRODUCTION

1

1.1

Background

1

1.2

Contract Details

2

1.3

Terms of Reference

2

1.4

Preliminary Design Report

3

TABLE OF CONTENTS EXECUTIVE SUMMARY

ES-1

E1. Introduction

ES-1

E2. Economic Evaluation

ES-2


ES-2

E4. Traffic Surveys

ES-3

E5. Traffic Growth and Projected Traffic

ES-3


ES-4

E7. Pavement Design

ES-5

E8. Materials Investigation

ES-6

E9. Hydrology

ES-7

1

2


ES-10


ES-12

INTRODUCTION

1

1.1

Background

1

1.2

Contract Details

2

1.3

Terms of Reference

2

1.4

Preliminary Design Report

3

1.5

Packaging of the Project Roads

3

1.6

This Report

3

ENGINEERING STUDIES

4

2.1

4

Project Location

2.1.1

Description of Project Road

4

2.1.2

Topography

7

2.1.3

Geology

8

2.1.4

Soils

8

2.2

Topogr aphical and Aerial Survey

8

2.2.1

General

8

2.2.2

References and Datum

8

2.2.3

Ground Control And GPS Measurements

10

2.2.4

Interim Beacons And Total Station Measurements

10

2.2.5

Aerial Survey

10

2.2.6

Final Products

11

2.3

Traffic Surveys

11

2.3.1

Terms of Reference

11

2.3.2

Existing Traffic

12 i

2.3.3

Traffic Counts

12

2.3.4

Base Traffic

13

2.3.5

Traffic Growth

15

2.3.6

Growth in normal traffic

15

2.3.7

Diverted Traffic

15

2.3.8

Generated traffic

15

2.3.9

Projected Traffic growth

15

2.3.10 Origin/Destination Surveys

16

2.3.11 Axle Load Survey

22

2.3.12 Overloading

23

2.3.13 Cumulative Equivalent Standard Axles (CESA)

24

2.3.14 Summarized Road Usage

25

2.3.15 Sensitivity Analysis

26

2.4

Soils and Materials Investi gation s

27

2.4.1

General

27

2.4.2

Sub-grade Soil Investigation

27

2.4.3

Gravel and Hardstone Sources

27

2.4.4

Laboratory Testing

28

2.5

Hydrol ogi cal Studi es

29

2.5.1

Objectives

29

2.5.2

General Objective

29

2.53

Specific Objectives

29

2.5.4

Background

29

2.5.5

Hydrological Analysis – Criteria and Practices

30

2.5.6

Hydrological Analysis – Methodology

30

2.5.7

Data Collection

31

2.5.8

Topography, Catchment Area Delineation and Watershed Parameters

31

2.5.8

Watershed Characteristics

32

2.6

Swamp Investig ations

36

2.7

Drainage Investigations

36

2.7.1 Assessment of Existing Drainage Structures

36

2.7.2

Classification of Drainage Structures

36

2.7.3

Side Ditches

37

2.7.4

Pipe Culverts

37

2.7.5

Box Culverts

37

2.7.6

Bridges

37

2.7.7

Existing Bridges

38

ii

2.7.8 2.8

3

Summary

Enviro nment al and Social Studies

38 38

2.8.1

General

38

2.8.2

Geographical Location

38

2.8.3

Biophysical Environment

39

2.8.4

Socio-economic and Cultural Environment

39

2.8.5

Predicted Environment and Social Impacts

40

DETAILED DESIGN

43

3.1

43

Geometric Desig n

3.1.1

Introduction

43

3.1.2

Design Standards

43

3.1.3

Design Speed

45

3.1.4

Design Departures

47

3.1.5

Cross-Section

48

3.1.6

Embankment Design

48

3.1.7

Adopted Design Parameters and Standards

49

3.1.7

Summary of Adopted Design Speeds

50

3.1.8

Design Road Alignment

50

3.1.9

Alignment Details

51

3.1.10 Low Lying Area

54

3.1.11 Junctions and Accesses

56

3.1.12 Footpaths, Busbays and Road Furniture

57

3.1.13 Service Roads

57

3.1.14 Climbing Lanes

58

3.2

Pavement Design

61

3.2.1

Introduction

61

3.2.2

Design Period

61

3.2.3

Pavement Design Input Data

62

3.2.3

Subgrade

62

3.2.4

Soft spots and Marshy areas

63

3.2.5

Pavement Materials

63

3.2.6

Pavement Design Catalogue

63

3.2.7

Pavement Structural Design

63

3.2.8

Design Traffic Loading

64

3.2.9

Design Subgrade CBR

64

3.2.10 Design Subgrade Class

66

3.2.11 Proposed Pavement Structure

66 iii

3.3

Drainage Design

67

3.3.1

Design Return Period

67

3.3.2

Frequency Distribution Models

67

3.3.3

Design Flood Estimation

70

3.3.4

Runoff Models

70

3.3.5

Frequency analysis

70

3.3.6

The TRRL East African Flood Model

71

3.1.8

Design Discharges

79

3.4

Struc tur e Selecti on

80

3.4.1

Design Philosophy

80

3.4.2

Bridges

81

3.4.3

Slab/Box Culverts

84

3.4.4

Pipe Culverts

85

3.4.5

Paved Side Ditches

87

3.5

Hydrauli c Desig n

87

3.5.1

Minor Drainage Structures

87

3.5.2

Major Drainage Structures

88

3.6

Struc tur al Desig n

90

3.6.1

Minor Drainage Structures

90

3.6.2

Major Drainage Structures

90

Quantit y and Cost Estimati on

97

3.7

3.7.1

Determination of Quantities

97

3.7.2

Unit Rates

97

3.7.3

Provisions

97

3.7.4

Construction Cost Estimates

98

3.7.5

Road Construction Packages

98

APPENDICES

Appendix 1 – Terms of Reference (Detailed Design) Appendix 2A – Survey Location Map Appendix 2B – Daily Count Results Appendix 2C – Estimated AADT Appendix 2D – Derivation of Growth Rates Appendix 2E – Traffic Forecast Appendix 2F – O/D Survey Results Appendix 2G – Sensitivity Analysis Results Appendix 3 – Summaries of Test Results Appendix 4 – Delineated Catchments

iv

Appendix 5A – Drainage Inventory Appendix 5B – Photographic Inventory Appendix 5C - Design Flows and Proposed Structures Appendix 6 - Structural Design Calculations Appendix 7 - Geometric Alignment Data

v

EXECUTIVE SUMMARY E1. Introduction

The Uganda National Roads Authority (UNRA) became a legal entity in 2006 and began operations in July 2008 with the following objectives at local level: 1. To improve access to goods/passenger transport services and to reduce transport costs along the route; 2. To improve access to social and economic development opportunities along the route by providing high capacity infrastructure; 3. To ensure no roadside communities become worse off as a result of the road upgrading works

In pursuance of the above objectives, UNRA has embarked on upgrading selected roads in several districts of Uganda. To this end, in September 2009, UNRA commissioned SMEC International Pty in association with NEWPLAN Ltd. of Uganda to provide consultancy services for the upgrading of several roads, referred to as Lot E, in the Eastern districts and comprising the following roads,

Road Reference No.

Road Name(s)

E1

Musita-Lumino and Busia-Majanji roads (104 Km)

E2

Tirinyi-Pallisa-Kumi and Pallisa-Mbale roads (114 Km)

E3

Mbale-Bubulo-Lwakhakha road (41 Km)

E4

Namagumba-Budadiri-Nalugugu road (29 Km)

E5

Kamuli-Bukungu road (64 Km)

with the following Terms of Reference: (i)

Feasibility Study, including consideration of alternative routes and pavement options, environmental and social impact study, road safety, land acquisition, preliminary design, economic and financial analysis;

(ii)

Detailed engineering design for the approved road option; including all necessary data collection, field surveys and analysis to cover all aspects of detailed design;

(iii)

Environmental and Social Impact Assessment (EIA) in accordance with Ugandan legislation and NEMA guidelines;

(iv)

Preparation of a full Resettlement Action Plan and associated surveys to identify and value property that will be affected by the road upgrading works and the establishment of the road reserve;

(v)

Preparation of bidding documents based on the approved detailed designs.

The Feasibility Study and the Preliminary Designs of the five project roads were undertaken between January 2010 and January 2011 and the Preliminary Reports submitted to UNRA variously between October 2010 and January 2011.

| FINAL Detailed Design Report_ Rev.1-AUG 2012 |

ES-1

Following consultations with UNRA, the five roads were divided into six (6) packages as follows:

Package 1 :

Road E1 :

Musita-Lumino/Busia-Majanji roads

Package 2A : Road E2.1/E2.2 : Tirinyi-Pallisa/Pallisa-Kumi road Package 2B : Road E2.3 :

Pallisa-Kamonkoli road

Package 3 : Road E3 :

Bumbobi-Busumbu-Lwakhakha


Namagumba-Budadiri-Nalugugu


Kamuli-Bukungu road

This Detailed Design report refers to Package 1: Road E1: Musita-Lumino/Busia-Majanji roads. The Project road starts from Musita trading center along the Jinja-Iganga highway passing through Mayuge, Nankona, Buyinja and ends at Lumino trading center, another link starts from Busia town through Lumino ending at Majanji. It acts as a shortcut from Busia town to Jinja and also serves as a link to a number of landing sites along Lake Victoria including Majanji, Lufudu, Omenya, Wakawaka and Kigandala. E2. Economic Evaluation

The economic evaluation of Road E1 indicated the upgrading of these roads to bitumen standards to be economically viable with the following Economic Internal Rates of Return: Table 1: Results of the Economic Evaluation (Net Present Value-NPV)

SN

E1

Road name/Road section

Musita-Lumino/Busia/Majanji ●1.1-Musita-Lumino ●1.2-Busia-Majanji

Type of HDM 4 analysis Project Section Section

NPV 50.682 28.764 21.918

Table 2: Results of the Economic Evaluation (Internal Rate of Return)

SN

E1

Road name/Road section

Musita-Lumino/Busia/Majanji ●1.1-Musita-Lumino ●1.2-Busia-Majanji

Type of HDM 4 analysis Project Section Section

EIRR (%) 19.6 18.0 24.0


Aerial photography supplemented by ground control was carried out during the preliminary design stage and formed the basis of the preliminary and detailed alignment designs.


ES-2

E4. Traffic Surveys th

Manual classified counts were carried at seven stations along the route for seven days, from 25 to st 31 March 2010. Night counts were carried for one weekday and one weekend day at each station. The average annual daily traffic (AADT) in the current year (2010) is indicated in the chart below, with vehicular traffic ranging from 154 to 557 vehicles/day.

2500 2090

2000 1430

1500

T D A A 1000

946

1046 829

564

557 337

500 154

272

246

200

0

5km after Lumino

5km before 5km before 5km from Namayingo Mayuge Busia Sation name AADT (with Motorcycles) Motorcycles)

5km from Musita

5km before Lumino

AADT (without motorcycles) motorcycles)

The proportion of motorcycles to the other traffic is high as seen from the chart above. Origin/Destination (OD) survey was conducted during the month of April 2010 using enumerators hired and trained from along the project road. Information gathered through road side interviews of vehicle drivers was analyzed to understand the origin-destination characteristics of traffic plying the project roads. Since these interviews were conducted on a sample of vehicles, the collected information was expanded to reflect the total volume of traffic plying on the road on that particular particular day. The results are discussed fully in the main text. E5. Traffic Growth and Projected Traffic

Deriving traffic growth from traffic data involves analysis of the growth of the various traffic classes over a long period of say 10-20 years. This growth will give a trend in the growth of traffic over the years. This trend is then used to project the traffic growth in the project period. It was noted that analysis of historical data was not feasible as there was no adequate historical data. Traffic growth factors were derived using traffic proxies such as fuel consumption, vehicle registration trends, GDP growth etc. No data on historical historical traffic growth was available for this t his road. It was assumed that road construction shall commence in the year 2011 and end in 2015. Projections were made for a design period of 15 years and 20 years. Therefore projections were made up to the year 2030 and 2035 using the corresponding growth factors. The following tables gives the forecast growth rates for the varios classes of vehicles for three scenarios, namely pessimistic (low), realistic (medium) and optimistic (high).

| FINAL Detailed Design Report_ Report_ Rev.1-AUG 2012 |

ES-3

Vehicle class

Cars Pick up and vans (Petrol) Pick up and vans vans (Diesel) Minibuses (Petrol) Minibuses (Diesel) Buses & Trucks

Vehicle class

Cars Pick up and vans (Petrol) Pick up and vans (Diesel) Minibuses (Petrol) Minibuses (Diesel) Buses & Trucks

Pessimistic normal traffic growth (%) 2024 and 2010-2013 2014-2018 2019-2023 beyond 4.7 5.7 3.7 2.4 4.7 5.7 3.7 2.4 4.7 6.8 4.4 2.9 4.7 5.7 3.4 2.4 4.7 6.8 4.4 2.9 4.7 6.8 4.4 2.9 Realistic normal traffic growth (%) 2024 and 2010-2013 2014-2018 2019-2023 beyond 4.7 7.2 4.7 3.2 4.7 7.2 4.7 3.2 4.7 8.5 5.6 3.8 4.7 7.2 4.7 3.2 4.7 8.5 5.6 3.8 4.7 8.5 5.6 3.8

Optimistic normal traffic growth (%) Vehicle class

Cars Pick up and vans (Petrol) Pick up and vans (Diesel) Minibuses (Petrol) Minibuses (Diesel) Buses & Trucks

2010-2013 4.7 4.7 4.7 4.7 4.7 4.7

2014-2018 8.6 8.6 10 8.6 10 10

2019-2023 5.7 5.7 6.8 5.7 6.8 6.8

2024 and beyond 3.9 3.9 4.6 3.9 4.6 4.6


A three day traffic axle load survey and counts was carried at Nabigingo along the project road th nd between 6 May and 22 May 2010. Weighing was done for both directions simultaneously using a portable weighbridge to Transport Research Laboratories (TRRL) specifications. The vehicles weighed were: - Medium Buses - Large Buses - Light Goods Vehicles - Medium Goods Vehicles - Heavy Goods Vehicles - Very Heavy Goods Vehicles The tables below shows the summary of axle load equivalence factor for each class of the heavy vehicles.


ES-4

Average gross weight 4.77

Average equivalence factor (80KN) 0.01

LB 1.2

14.68

1.69

LGV (1.2)

4.26

0.07

MGV(1.2)

4.10

0.00

HGV 1.2

5.38

0.11

VHGV 1.2

18.65

9.61

Vehicle category MB 1.2

E7. Pavement Design

The pavement design of the project roads is based on the Ministry of Works, Housing and Communications Road Design Manual Vol. 3: Pavement Design, Part I: Flexible Pavements (July 2005). The economical analysis of the project roads is based on a 20 year analysis period. Hence a 20 year pavement design period has been adopted. Projected traffic loading for low, medium and hight growth scenarios are: 6

Estimated Estimated traffic growth rate (low) Estimated traffic growth rate (medium) Estimated traffic growth rate (high)

= 8.7x10 6 = 8.99x10 = 9.37x106

Estimated traffic growth rate (medium) pavement pavement structure

= 8.99x10 is adopted for the design of the

Traffic class obtained is:

6

T6

Subgrade Class: Analysis of soaked CBR test results for the road alignment subgrade soil is presented in summary summary form as shown shown below.

Musita - Lumino Chainage

Road Length

Road From

To

(Km)

90th percentile value

Design CBR (%)

Subgrade Class

Musita-Lumino

0+000- 74+000

74.0

6

6

S3

Busia-Majanji

0+000-26+000

26.0

6

6

S3

Following the submission of the Preliminary Design Report, UNRA instructed the Consultant to adopt Chart W2 of the Design Manual for the selection of the pavement structure.


ES-5

On the basis of the projected traffic loading, the following pavement structure has been recommended:

Pavement layer

Type of material

Layer thickness

SURFACING BASE COURSE SUBBASE IMPROVED SUBGRADE

AC(Asphalt Concrete) GB(Granular Base) CSB(Cemented Subbase) G15 (Natural Gravel CBR >15%)

50 mm 150 mm 175 mm 125 mm

AC – Asphalt Concrete GB – Granular Base (Graded Crushed Stone) CSB – Cement Stabilized Base (Gravel) G15 – Gravel Class 15 (min.CBR=15) E8. Materials Investigation

The preliminary materials investigations were conducted in accordance with the Terms of Reference. It consisted of site reconnaissance, field exploration and analysis of the findings of the field exploration. Sub-grade Soil Investigation The sub-grade soil investigation along the existing road alignment comprised sub-grade soil sampling by means of trail pits, DCP testing and laboratory testing. Trial Pits Trial pits were excavated at two (2) kilometre interval on alternate side of the carriageway to depths of generally 1 m. The pits were dug to varying depths from the surface to sub-grade level with a total of 34 pits dug over the total road length of the project road 68 km. The vertical profile of the pavement in each trial pit was recorded and representative sub-grade sample taken for laboratory testing.

DCP Investigations DCP tests were conducted at intervals of 500m as stipulated in the ToR to measure the in-situ bearing strength (CBR) of the sub-grade. To avoid weak spots (thin layers) from being overlooked and to identify layer boundaries fairly accurately, readings were taken at 1-5 blow intervals, depending on the rate of penetration. Gravel and Hardstone Sources

-

Assessment of the suitability and extent of the material source.

-

Excavation of trial pits.

-

Logging of the layers encountered.

-

Retrieval of samples for laboratory testing.

-

Backfilling of the trial pits.


ES-6

At each site, trial pits were excavated and depths of overburden and gravel were logged. In some instances, material was sampled from rock outcrops, talus, or existing quarries, in which cases, test pit excavation was not required. The volumes of both overburden and gravel were also estimated. 

Gravel and Hardstone Sources

A total of 20 existing and potential gravel sources and 3 rock sources were identified and investigated along the five project roads as listed below: Laboratory Testing As a requirement under the Contract, the Consultant fabricated a mobile laboratory in a 40-foot container at its offices in Kampala. Upon completion of fabrication and fitting out the laboratory was transported and erected at the compound of UNRA’s regional offices in Jinja. 

Gravel Samples

Samples of sub-grade material recovered from trial pits and samples from the gravel sources were transported to the mobile laboratory in Jinja where they were subjected to the following tests:

-

Natural moisture content determination

-

Particle size analysis

-

Atterberg limits

-

Moisture content – Dry density relationship (BS 1377 test method)

-

CBR (4-day soak compacted at 90%, 95% and 98% MDD)

-

Swell tests

 Rock

Samples

To confirm the test results obtained on surface samples, during the detailed design stage the existing operational quarry along Musita-Lumino road was drilled at one location down to 15 m. Samples of cores were taken to the Ministry of Works’ central testing laboratory at Kireka where they were tested for:

- Specific Gravity - Ten Percent Fines Value (TFV) - dry - Ten Percent Fines Value (TFV) – wet - Water adsorption - Sodium Sulphate Soundness - Bitumen Affinity The investigations and the test results indicate that there is sufficient gravel and rock meeting the specifications available for the designed pavement structure. E9. Hydrology

The objectives of the services as per the terms of reference (TOR) issued to the Consultants are:


ES-7

 To undertake hydrological and hydraulic assessment for the project roads under Lot E  To prepare Hydrological Reports as per the Terms of Reference Specific Objectives are:

   

Collect and compile hydrological data for the project roads Carry out hydrological analysis for various drainage basins and channels traversed by the road, Computation of design discharges for the existing and proposed drainage structures along the roads Preparation of hydrological report for the project

The Road Drainage Design Manual (2005) guidelines require a designer to develop a clear understanding of the existing drainage conditions for a given assignment before determining the capacity of the existing cross and lateral drainage structures. Minor drainage structures e.g. side ditches are to be designed to carry a 10-year flood while major ones must be evaluated for the 25-100 year storm. The RDDM (Table 3.2) suggests suitable return periods for various structural categories. Whenever possible, it is required that adequate openings are provided to limit backwater effects and excessive bed scour. The TRRL East African Model has been widely applied and found to be more relevant in East Africa since a number of small catchments were extensively studied prior to establishing the required parameters for its application. The watersheds draining to project road have distinct characteristics largely due to their geographical location, climate and land use characteristics. The relatively common aspect is that the watersheds are intensively cultivated, human settled and predominantly rolling. The Musita-Lumino/Busia-Majanji roads are characterized by:

 Natural vegetation similar to tropical forest/ grassland.  Low-lying areas  Tropical climate with rainfall having two seasons i.e. from March to June and from September to November (Bimodal)



Agriculture (sugar canes, maize, cassava, sweet potatoes, millet and sorghum), Cattle rearing and mining like gold, uranium, iron core, lake sand and oil.

Design Discharges The tables below gives the design discharges of the project road under the project for the different return periods.


ES-8

Summary of design floods for different return period Road E1.1- Musita-Lumino 3 Design flood discharge (m /s) Chainage Catch. Catch. from Northing Easting area Ref. 2 (km ) Musita 10-yr 25-yr 50-yr 100-yr 283 5+060 546926 55901 1.34 6.28 7.02 7.69 8.75 284 5+440 547329 55567 1.18 5.56 6.22 6.80 7.74 286 7+276 548534 54543 8.62 40.47 45.27 49.56 56.36 287 11+250 551778 51971 0.74 3.66 4.09 4.48 5.09 289 11+660 554420 50807 1.24 3.83 4.28 4.69 5.33 290 15+870 556063 50594 4.78 14.72 16.46 18.02 20.50 292 16+833 558983 50334 1.54 7.86 8.79 9.62 10.94 293 18+800 559865 50573 0.42 1.28 1.44 1.57 1.79 294 19+700 561223 50599 0.21 0.64 0.72 0.78 0.89 295 21+100 562439 50433 0.40 1.24 1.39 1.52 1.73 296 24+000 564029 50880 2.03 6.26 7.00 7.66 8.72 297 25+810 565785 50809 0.29 0.88 0.99 1.08 1.23 298 28+640 568503 50122 0.73 2.24 2.50 2.74 3.11 299 29+465 569306 50281 1.18 5.53 6.18 6.77 7.69 300 30+910 570662 50663 0.71 2.17 2.43 2.66 3.03 31+970 571704 50447 0.44 1.29 1.46 1.59 1.99 34+360 574025 50099 14.32 44.12 49.35 54.03 61.44 301 574151 50076 302 37+960 577490 50202 3.75 11.56 12.93 14.16 16.10 40+240 579850 50501 24.97 88.43 98.91 108.29 123.15 303-306 582090 50406 582238 50370 307 45+990 585222 49136 9.09 42.58 47.63 52.14 59.3 308 50+260 588250 46187 11.47 49.98 55.9 61.2 69.6 309 54+130 591146 41090 13.18 42.82 47.89 52.43 59.63 310 54+870 591696 43504 10.54 32.48 36.33 39.77 45.23 311 58+590 594212 40880 12.42 30.38 33.98 37.2 42.31 312 63+270 597842 38019 1.13 7.01 7.84 8.59 9.76 313 73+330 607154 35225 3.26 17.82 19.93 21.82 24.81 314 76+660 610229 36199 0.97 3.00 3.36 3.67 4.18 Summary of design floods for different return period Road E1.2- Busia-Majanji 3 Design flood discharge (m /s) Chainage Catch. Catch. area from Northing Easting (km2) Ref. Busia 10-yr 25-yr 50-yr 100-yr 325 1+125 620283 51064 0.19 0.88 0.98 1.07 1.22 324 1+480 619949 50892 0.57 2.87 3.21 3.51 3.99 323 6+970 616014 47143 2.0 10.03 11.22 12.29 13.97 322 10+310 614350 44331 0.88 4.41 4.94 5.4 6.14 0.16 321 10+885 614081 43819 0.81 0.90 0.99 1.12 320 11+860 613606 42931 8.35 24.68 27.61 30.22 34.37 16+310 611423 38133 3.96 17.82 19.94 21.83 24.82 318 17+390 610871 36614 317 21+600 610325 34182 4.96 22.18 24.81 27.16 30.89 | FINAL Detailed Design Report_ Rev.1-AUG 2012 |

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316 315

23+180 25+500

610300 610374

32610 30420

0.80 1.38

3.12 5.36

3.49 5.99

3.82 6.56

3.12 7.46


Assessment of Existing Drainage Structures A visual assessment of the drainage structures was carried out by the Bridge/Drainage Engineer and the Hydrologist. Each minor and major drainage structure was inspected and relevant basic measurements were taken. Data on hydraulic performance and history of any overtopping and history of rehabilitation measures undertaken were collected from local residents and branch of the ministry of works. Moreover, observations were made relating to:         

Hydraulic performance Physical condition Possible causes of damage Materials used for construction and their performance Period of service Possible reasons for poor performance Possibility of maintenance or repair Performance in respect to traffic safety Replacement options

A detailed photographic inventory and assessment of all the existing drainage structures are prepared following the field inspection. Classification of Drainage Structures For the purpose of this project, all drainage structures are classified in two broad classes namely, minor and major drainage structures. Minor Structures Minor drainage structures are those pipes having single or multiple cell opening either made from concrete or corrugated metal sheet (Armco) and all the road side drainage facilities. Major Structures Structures included in Major Structure’s category are box culverts, slab culverts and reinforced concrete /composite/ steel / bridges. Slab culverts are those with top slab resting on abutments done separately, and box culverts are those having monolithic top slab, bottom slab and the vertical walls. Side Ditches Stone pitched side channels and flow checks are found along a certain sections of the project roads. Some are recently constructed and are in very good condition. But in general it is observed that due to lack of regular repair, water flows out of the channel damaged the road pavment and make it difficult for road users. Please refer to table 1 in Appendix 8.2 for details. Pipe Culverts According to the structures inventory data, there are over 300 existing pipe culverts along all the project routes. The majority of the existing pipe culverts are made from either reinforced concrete | FINAL Detailed Design Report_ Rev.1-AUG 2012 |

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with internal diameter ranging from 300mm to 1000mm or Armco sheet ranging from 600mm to 2000mm internal diameter. During assesmsnt of the drainage structures along the project route, thefollowing major deficiencies or problems were observed at pipe culverts:

      

Damaged or missing headwalls Siltation in pipes due to low invert level Poor workmanship at the head walls and at pipe joints. Insufficient length of pipes as compared to the width of the road Insufficient hydraulic capacity Lack of regular cleaning Missing or damaged aprons and energy dissipaters at inlets and outlets

Box Culverts More than six box/slab culverts are found along the entire project route. The following major deficiencies or problems were observed at box/slab culverts during the assessment:

    

Deteriorated slab concrete Cracked, damaged abutments and wing walls Insufficient hydraulic capacity Eroded bank and scoured bed. Damaged inlet and outlet aprons (either broken down or dislodged)

Bridges There are no existing bridges along Musita- Lumino and Busia - Majanji roads. Recommeded Structures The list of recommended drainage structures are listed in the Appendix to this report. They comprise: Pipe Culverts: Single 900 mm : Twin 900 mm : Single 1050 mm : Twin 1050 mm : Single 1200 mm : Twin 1200 mm :

53 No. 7 No. 7 No. 1 No. 4 No. 4 No.

Box Culverts: 2m x 2m single cell: 3m x 2m single cell: 4m x 2m single cell: 4m x 2m twin cell: 4m x 2.5m single cell: 4m x 2.5m twin cell:

6 No. 3 No. 4 No. 3 No. 3 No. 3 No.


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Design Standards In accordance with the requirements of the TOR, and as confirmed by UNRA, the designs were to be based on the Ugandan MoWH&C Road Design Manual of July 2005. In order to realize the most economic design solution this Manual was complimented by recognised design manuals from neighbouring counties including;



Kenya’s Road Design Manual – Part 1: Geometric Design Manual



Tanzania’s Draft Road Manual

 Code of Practice for Geometric Design (SATCC-1998) – Trunk Road Design Standards On the basis of the Ugandan Road Design Manual, the ideal functional classification for the project road is Class C or a Primary road. These are described as roads linking provincially important centers to each other or to a higher class roads (urban/rural centers). They provide linkage between districts, local centers of population and development areas with higher class road. Their major function is to provide both mobility and access A paved Class II road standard was adopted for design; the applicable geometric design standards for which are presented in Figure 4.2a and 4.2b of Section 4 of the Design Manual. Design Speed For a Bitumen Class II road traversing a flat terrain (max grades of 5.5%), a design speeds of 90 km/h was recommended. It should however be noted that many sections of the existing road are long and straight and higher speeds than these will be possible. Through the more populated centres along the route, a design speed of 50 kph has been set. This speed applies in sections and locations given in the Table 10.2 in the main report. The traffic speed in the above locations shall be regulated through the installation of road signage, speed bumps and rumble strips. Cross-Section After consultation with UNRA a cross section comprising 3.5 m lanes and 1.5 m shoulders was adopted for the project road. In towns/urban areas the shoulder width was increased to 2.0 m. Summary Of Adopted Design Parameters And Standards The following parameters and standards have been adopted in the designs: Design life:

20 years.

Cross-section:

7.0 m wide carriageway at 2.5% normal camber 1.50 m wide shoulders at 4.0 % normal crossfall (2.0 m in urban areas) 1.0 m wide side drain.


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Desig n Speed Parameters: Desig n Speed

90 Km/h

70 Km/h

Min. Horizontal Radius

320 m

185 m 7%

Max. Superelevation Max Gradient (Absolute)

5.5%

7.5%

0.4-0.6 max

Rate of Change of Superelevation Minimum Crest Curve Kmin (stopping sight distance)

71

31

Minimum Sag Curve Kmin

41

25

Stopping Sight Distance (SSD)

170 m

111 m

Passing sight Distance

750 m

550 m

Selection Of Alignment The following principles were adopted during selection of an appropriate alignment for the detailed design:



Conformity to the specified geometric design parameters.

The alignment was designed to conform to or surpass the geometric design parameters as recommended in the design manual.



Follow the general corridor of the existing road.

The general approach to the route alignment was to use the corridor of the existing road as much as possible. This was done to retain the present social function with minimum disruption to existing and long-term residents. Minor realignments were however introduced to improve the road geometry and remove potentially dangerous curves. This was also done at locations of new bridges.



Keep the works within the existing right of way.

In most sections, the alignment design was carried out to follow the existing road as much as possible to enable the use of existing pavement materials to form new a subgrade.



Improve junctions.


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In order to improve safety at the approach junctions, the project road has been realigned to approach the main highway at a right angle.



Re-align at trading centres.

There are a number of large trading centers along the project roads with heavy population and agricultural activities. The possibility of having a bypass at some of these centers was investigated. Preliminary realignments outside the centers were designed. These were then presented to the Resettlement and Land Acquisition specialist who also visited the project road to evaluate the impact of the bypasses against keeping the alignment through the centers, compensating where necessary and maintaining the current social function of the road.


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1 INTRODUCTION 1.1

Background The Uganda National Roads Authority (UNRA) became a legal entity in 2006 and began operations in July 2008 with the mission: “to develop and maintain a national road network that is responsive to the economic development needs of Uganda, to the safety of all road users, and to the environmental sustainability of the national road corridors.”

At local level UNRA’s objectives are: 4. To improve access to goods/passenger transport services and to reduce transport costs along the route; 5. To improve access to social and economic development opportunities along the route by providing high capacity infrastructure; 6. To ensure no roadside communities become worse off as a result of the road upgrading works

On This contract was executed on 1 st September 2009. Under the agreed terms and conditions of the contract the effective date of commencement of the services was set at 27th November 2009. In pursuance of the above objectives, UNRA has embarked on upgrading selected roads in several districts of Uganda. To this end UNRA accepted the proposal of SMEC International Pty in association with NEWPLAN Ltd. of Uganda to provide consultancy services for the upgrading of several roads, referred to as Lot E, in the Eastern districts and comprising the following roads: Road Reference No. E1.1/E1.2

Road Name(s) Musita-Lumino and Busia-Majanji roads (104 Km)

E2.1/E2.2/E2.3 Tirinyi-Pallisa-Kumi and Pallisa-Mbale roads (114 Km) E3

Mbale-Bubulo-Lwakhakha road (41 Km)

E4

Namagumba-Budadiri-Nalugugu road (41 Km)

E5

Kamuli-Bukungu road (64 Km)

| FINAL Detailed Design Report _ Rev.1-AUG.2012 |

1

1.2

Contr act Details This contract was executed on 1 st September 2009. Under the agreed terms and conditions of the contract the effective date of commencement of the services was set at 27th November 2009. CLIENT

Uganda National Roads Authority

CONSULTANT

SMEC International Pty Ltd. In association with NEWPLAN Ltd

CONTRACT PHASES

Phase 1: Feasibility Study and Detailed Engineering Design Phase 2: Tender Assistance Phase 3 : Project Management

CONTRACT TIME

Phase 1 & Phase 2: 10 months Phase 3 : 48 months

CONTRACT VALUES

Phase 1 : UGX 320,881,504 + USD 3,307,169 Phase 2 : UGX

7,630,560 + USD

122,557

Phase 3 : UGX 609,074,334 + USD 2,116,351 CONTRACT EXECUTION DATE

1st September 2009

CONTRACT COMPLETION DATE

Phase 1 + Phase 2 : 30 th September 2010

Phases 2 and 3 were subsequently omitted by the Client.

1.3

Terms of Reference The main objectives of these Consultancy Services are: (vi)

Feasibility Study, including consideration of alternative routes and pavement options, environmental and social impact study, road safety, land acquisition, preliminary design, economic and financial analysis;

(vii)

Detailed engineering design for the approved road option; including all necessary data collection, field surveys and analysis to cover all aspects of detailed design;

(viii)

Environmental and Social Impact Assessment (EIA) in accordance with Ugandan legislation and NEMA guidelines;

(ix)

Preparation of a full Resettlement Action Plan and associated surveys to identify and value property that will be affected by the road upgrading works and the establishment of the road reserve;

(x)

Preparation of bidding documents based on the approved detailed designs.

The Terms of Reference relating to the detailed design phase are included in Appendix 1.


2

1.4

Prelimi nary Design Repor t The Preliminary Design Report was submitted to UNRA in October 2010. The Report was submitted in two (2) volumes, namely: Volume 1A: Volume 1B: Volume 2.1: Volume 2.2: Volume 2.3: Volume 2.4: Volume 2.5:

Main Text Appendices Book of Drawings – Road 1 (Musita-Lumino/Busia-Majanji) Book of Drawings – Road 2 (Tirinyi-Pallisa-Kumi/PallisaKamonkoli) Book of Drawings – Road 3 (Bumbobi-Bubulo-BusumbuLwakhakha) Book of Drawings – Road 4 (Namagumba-Budadiri-Nalugugu) Book of Drawings – Road 5 (Kamuli-Bukungu)

The Consultant received the Client’s comments on the Preliminary Design Report variously in February and July 2011.

1.5 Packaging of the Project Roads Based on the preliminary construction cost estimates, the lengths and geographic locations of the project roads, the Consultant recommended, and agreed by the Client, that the project be divided into six (6) distinct packages for the purpose of bidding as follows: Package 1 :

1.6

Road E1 :

Musita-Lumino/Busia-Majanji roads

Package 2A : Road E2.1/E2.2 :

Tirinyi-Pallisa/Pallisa-Kumi roads

Package 2B : Road E2.3 :

Pallisa-Kamonkoli road


Bumbobi-Busumbu-Lwakhakha road


Namagumba-Budadiri-Nalugugu road


Kamuli-Bukungu road

This Repor t This report relates to the Detailed Design for Package 1 - Road E1.1/E1.2 : Musi ta-Lumi no/Bus ia-Majanji roads.


3

2

ENGINEERING STUDIES

2.1

Project Locatio n Lot E roads are located in the Eastern districts of Uganda and cover the five roads as indicated on the frontispiece.

2.1.1

Description of Project Road

The project road is discussed below. The lengths indicated are based on the final design chainages. Road Links Name

(i) Musita – Nankoma (ii) Nankoma - Buyinja (iii) Buyinja – Lumino (iv) Busia – Majanji TOTAL

Length (km)

36 26 15 26 103


4

MUSITA

BUSIA

-

LUMINO

MAJANJI

Figure 1 : Loc ation of Musi ta-Lumino/Busia-Majanji Roads

5

(a) Alignment The road traverses the Mayuge, Bugiri and Busia districts, starting at the Musita trading centre at its junction with the Jinja - Iganga road. The terrain is flat to gently rolling terrain Start at Musita Km and the horizontal and vertical alignments 0+000 are gentle with good visibility. The riding surface width is generally 5m – 5.5m. The Nankoma-Namayingo link has recently been subjected to periodic maintenance by UNRA involving regravelling

Alignment at Km 27

Alignment at Km 2

Alignment and surface at Km 30.8

(b) Road condition The road is a gravel road with generally good riding surface with a few exceptions where gullies have developed on the road surface. Km 5 – Gullies in the road surface

Stretch along BusiaMajanji road

(a) Alignment The road traverses the Mayuge, Bugiri and Busia districts, starting at the Musita trading centre at its junction with the Jinja - Iganga road. The terrain is flat to gently rolling terrain Start at Musita Km and the horizontal and vertical alignments 0+000 are gentle with good visibility. The riding surface width is generally 5m – 5.5m. The Nankoma-Namayingo link has recently been subjected to periodic maintenance by UNRA involving regravelling

Alignment at Km 27

Alignment at Km 2

Alignment and surface at Km 30.8

(b) Road condition The road is a gravel road with generally good riding surface with a few exceptions where gullies have developed on the road surface. Km 5 – Gullies in the road surface

Stretch along BusiaMajanji road

( c) Land use Basically subsistence agriculture with maize, potatoes, cassava and rice. Cash crop grown along the road is sugarcane. Rice is grown in the marshy areas. Km 4.5 – Sugarcane being transported

Km 5.5 – Rice paddy in swamp

(d) Drainage Minor drainage structures consist of concrete pipes. There are no major structures in this section. Pipe culverts are generally silted up due to invert Levels being below ground level. There are stretches where erosion in side Erosion in side drain drains is evident.

Lined Drain at Km 31.6

Typical Mitre Drain

| FINAL Detailed Design Report_Rev.1-AUG.2012 |

6

(e) Construction materials There is an existing rock quarry at Km 2.6 and an existing borrow pit at Km 14. In addition, potential rock sources exist at Km 2.9, Km 11.8 and Km 18.2. Existing Rock Quarry at Km.2.6

Rock Outcrop at 11.8

Rock Outcrop at Km 30.6

Rock Outcrop at Km 31.4

(f) Trading Centres

Km.

Km 13 – Mayuge Trading centre

The link passes several trading centres, namely Buluba at Km 2, Mayuge at Km 13 and Mpungwe at Km 20.7. Km. 2 – Buluba Trading Centre -

Namayingo Trading Centre

2.1.2

Lumino trading centre end of link Km 49.3

Topography

The topography of the project area is relatively flat with high ridges and isolated hills, adulating low lands and perch vents with a few higher residual features. The hills are linear and of a convex nature scope and almost flat valleys. Some of the hills include Irimbi, Bululu and Namakoko in Bugiri district. The lowest point of about 1,200m above sea level is in the south along the Lake Victoria and the highest 1500m above sea level is found in the north.


7

The project area has a long shoreline of Lake Victoria in the south with several islands. (Statistical 2.1.3

Geology

In terms of geology, the project area is made up Precambrian rocks with bare granitic rocks at several places heavily eroded. Deposits of eroded soil can be witnessed in some parts of the low lands on farmers’ gardens and these tend to increase towards the lowlands. 2.1.4

Soils

The soils covering most of the project area are mainly loamy and sand loams with spots of clay at the valley areas. These soils have fine texture with rather loose structure, which are easily eroded and leached. The soil types can be summarized as;

 Yellow-red sandy, clay loam soils varying from dark grey to dark. These occur on gently undulating –hilly topography.  Brown yellow clay loams with laterite horizon with a variety of dark brown to dark grayish brown. These occur on flat ridge tops or as of undulating topography.  Light –grey- white mottled loamy soils with laterite horizon ground, structuresless loamy sands. These are acidic-allocative and mainly found on lower and bottom slopes.  Clay soils are limited to the swamps in the valleys. (Busia District State of Environment Report, 2005 and Bugiri District Development Plan 2009/10-2011/2012).

2.2

Topographical and Aerial Survey

2.2.1

General

The project roads with a total length of approximately 364 km was covered by colour aerial photographs to scale 1:8,000 in March 2010. Ground control designed for aerial triangulation was carried out for subsequent line and orthophoto mapping. Two inter-visible permanent beacons with description and photo, consisting of an iron pin in concrete 30 x 30 x 40 cm or a hole drilled in rock were constructed at intervals of 3 km along the specified routes i.e. Roads 1, 2, 3, 4, and 5 to serve as control for the inter-visible interim beacons which were constructed in between these control beacons along the routes. The interim beacons consists of an iron pin set in concrete 20 x 20 x 30 cm or a hole in rock when suitable. 2.2.2

References and Datum

Instruments and Software  Three units Leica GPS Receivers System 300 SKI software version 2.3   One Wild NA2 Automatic Level  One Wild A0 Automatic Level  One Zeiss NI2 Automatic Level | FINAL Detailed Design Report_Rev.1-AUG.2012 |

8

 

Two units Geodimeter 400 Total stations One Garmin, Etrex, handheld GPS receiver

References Datum Projection Grid Units

: : : :

Arc 1960 (NEW) Transverse Mercator UTM, Zone 36 N Metric

Datum Points in Plan and Heigh t UP50 E = 569809.367 N = 51853.173 51X1 E = 485710.686 N = 152493.050 52X2 E = 509491.943 N = 126569.501 52X3 E = 510506.248 N = 113620.011 53X2 E = 598100.184 N = 146594.827 53X8 E = 607124.549 N = 112349.993 53X10 E = 592040.310 N = 131016.272 54X3 E = 635475.290 N = 131108.840 64X1 E = 640423.259 N = 86844.067 64X2 E = 624537.248 N = 109977.442 62GP1 E = 518178.070 N = 110401.090 74GP1 E = 614717.168 N = 35615.815 K2 E = 535978.005 N = 60268.398 K3 E = 532200.518 N = 56074.307

Z = 1148.182 Ground level Z = 1486.205 Ground level Z = 1502.050 Ground level Z = 1064.210 Brass bolt Z = 1179.330 Brass bolt

UP50 Pillar destroyed, but holes in rock after anchor iron found and restored to within 5 cm. 51X1 Pillar destroyed, but holes in rock after anchor iron found and restored to within 5 cm. 52X2 Pillar destroyed, but holes in rock after anchor iron found and restored to within 5 cm. 52X3 Pillar destroyed, but holes in rock after anchor iron found and restored to within 5 cm. 53X2 Pillar destroyed, but holes in rock after anchor iron found and restored to within 5 cm. 53X8 Pillar destroyed, but holes in rock after anchor iron found and restored to within 5 cm. 53X10 Pillar destroyed, but holes in rock after anchor iron found and restored to within 5 cm. 54X3 Pillar destroyed, but holes in rock after anchor iron found and restored to within 5 cm. 64X1 Pillar destroyed, but holes in rock after anchor iron found and restored to within 5 cm. 64X2 Pillar destroyed, but holes in rock after anchor iron found and restored to within 5 cm.


9

62GP1 Short ground pillar with brass bolt found intact. 74GP1 Short ground pillar with brass bolt found intact.

2.2.3

K2

Iron pin in concrete found intact.

K3

Iron pin in concrete found intact.

Ground Control And GPS Measurements

A total of 219 GPS Beacons were constructed as inter-visible pairs after every 3 km along the five road alignments divided as follows: Musita-Lumino Road : ML01 – ML44 Busia-Majanji Road : LM1- LM5 and LB1 – LB12

A description card + photo was prepared for each of these points. Inter-visible Beacons were also constructed between the GPS Beacons with a maximum length not exceeding 500 m between the Beacons. Static Differential GPS measurements in combination with double run spirit leveling was deployed to obtain coordinates to cm accuracy in plan and height for the photo control points as well as GPS Beacons used as control points for the densification of beacons in between. This was coordinated using a Total station and measured as traverses between the control points with closing errors not less than 1:10,000 in plan. Double run spirit leveling was carried out to obtain reliable heights also for these points. 2.2.4

Interim Beacons And Total Station Measurements Coordinates in

plan are based on the following Trig stations: MusitaLumino/Busia-Majanji Road : UP50, 74GP1, K2 and K3

Heights are based on the following Trig stations: Musita-Lumino/Busia-Majanji Road :

74GP1 (brass bolt)

Static Differential GPS observations was carried out with observation times between 20 to 30 minutes on every station to obtain Cartesian coordinates in the WGS 84 system with subsequent transformation into the UTM System Arc 1960 datum using SKI software based on the control points mentioned above. Heighting Double run Spirit Levelling was carried out for all permanent Beacons, with relevels done for cases where error was greater than 10mm/km between forward and backward levelling. 2.2.5

Aerial Survey

Flight Permission Permission to fly over the project roads was obtained from Uganda Civil Aviation Authority on: 8 February 2010 for a 3-month period up to 8 May 2010.


10

Flight Dates Aerial photography for Musita-Lumino/Busia-Majanji roads was undertaken on 11th March 2010 and completed on 13th March 2010 with flight altitude of 705m above mean ground level Equipment  Aircraft: Piper Navajo PA 31 reg. 5Y-MAP, white with blue stripes  Camera equipment: Wild RC-10  Flight planning equipment: IGI WIN MP  Navigation equipment: IGI CCNS NOVATEL DL-V3  Film used: Agfa AVIPHOT X 100PE1  Film processing and printing:FUGRO/BKS, Northern Ireland 2.2.6 Final Products

Final products delivered after aerial photography and post-processing included: 1. Colour aerial photography at 1:8,000 scale inclusive of a ground GPS station operated simultaneously as the aerial photography was undertaken. 2. Quick View digital orthophoto for a minimum of 1.5 km width. 3.

Digital photogrammetric line mapping for a 60 m wide corridor inclusive of mapping streams 500 m upstreams and 500 m downstreams for a 100 m width at 10 bridge sites.

Other deliverables included: a) Hard and soft copy of the Aerial Photographs b) Flight Plans c) Caliberation Certificates d) DTM and x, y , z ground points @ 5 m intervals e) Detailed Survey Report Both the horizontal and vertical accuracies achieved were within the tolerances agreed with the Client, namely, Horizontal : Vertical :

As per ToR +/- 70mm

2.3

Traffi c Surveys

2.3.1

Terms of Reference

The ToR called for: 

Assembling all traffic data on the project roads with a view to determine the present pattern of traffic growth by vehicle class.



Agreement with UNRA on the location of and the number of traffic count stations (an average at one per 20km, and at least 5km from major junctions) where counts of motorized and non motorized vehicles, pedestrians and animals best represent present road usage.


11



Conducting classified counts at each location for a continuous period of not less than five days 12-hour and two days (1 week day and 1 weekend) for 24-hour taking into account fluctuations caused by local factors e.g. market days.



Determining traffic predictions by class for each station, for assumed low, medium and high growth predictions.



Carrying out axle load survey over a minimum period of 3 days per road, which was to include information on origin and destination of all vehicles stopped.

Classified counts were carried out in the months of March, April and May 2010. 2.3.2

Existing Traffic

Table 1 shows the historic data obtained from UNRA. Table 1: Historical data obtained from UNRA

Road name

ADT excludi ng motorcy cles

ADT includin g motorcy cles

ADT NMT

Musita-Mayuge-NankomaNamayingo-Lumino (U)

78

552

2628

Busia – Majanji (U)

63

263

1540

Table 1 shows that the road has a high number of NMT and motorcycles traffic. 2.3.3

Traffic Counts

Manual classified counts were carried at seven stations for seven days, from 25 th to 31st March 2010. Night counts were carried for one weekday and one weekend day at each station. The locations are described in Table 2 below and shown in Appendix 2A. The scope of non-motorized traffic (NMT) included bicycles, pedestrians and carts. The results from the study are attached in Appendix 2B. It was assumed that no traffic would be diverted from the alternative routes since these routes are shorter than the project road.


12

Table 2: Traffic Count Stations Locations

Dates

1. 5km after Lumino

25th 2010

2. 5km before Busia 3. 5km before Namayingo 4. 5km before (NMT)

Namayingo

Type of surv ey

31st March,

26th – 27th March, 2010

5. 5km from Mayuge

Classified Count Classified Count (Night Count)

6. 5km from Musita 7. 5km before Lumino

12h counts were expanded to 24h using the ratios of 24h to 12h traffic for each vehicle type and separately for weekday and weekend traffic. The details are shown in Table 3. Table 3: Observed ratio of 12 to 24 hour traffic Station number

Station location

Week day

Week end

12 hour t raffic as a percentage of 24 hour traffic

12 hour t raffic as a percentage of 24 hour traffic

1

5km after Lumino

87.3%

80.6%

2

5km before Busia

90.0%

88.2%

3

71.0%

74.0%

4

5km before Namayingo 5km from Mayuge

76.1%

69.5%

5

5km from Musita

77.7%

76.4%

6

5km before Lumino

73.9%

79.7%

2.3.4

Base Traffic

Table 4 shows the observed ADT at each of the counts station. Table 4: Summary of observed ADT at Count Stations Station no

1 2 3 4 5 6

Count station

5km after Lumino 5km before Busia 5km before Namayi ngo 5km from Mayuge 5km from Musita 5km before Lumino

Direction A

Direction B

Both directions

Directional distribution Vehicles PCU

Vehicles

PCU

Vehicles

PCU

Vehicles

PCU

117

147

120

173

237

319

49:51

46:54

1,010

1,173

1,078

1,274

2,089

2,446

48:52

48:52

472

578

473

671

945

1,249

50:50

46:54

408

539

420

536

828

1,075

49:51

50:50

706

1,153

724

1,236

1,430

2,389

49:51

48:52

607

761

442

579

1,049

1,340

58:42

57:43


13

As noted from Table 4, traffic increases towards the towns and trading centers such Busia and Musita. The traffic surveys were conducted in the period February – May 2010. Therefore the observed ADT needed to be factored for the season to arrive at the Annual Average Daily Traffic (AADT). However due to the absence of such data, a seasonal factor of 1 was assumed. Using the assumed seasonal factor of 1 (one), the AADT was calculated using the equation below.  =  ×  

Where AADT – Average Annual Daily Traffic. ADT – Average Daily Traffic. Figure 2 below shows estimated base year traffic composition at each of the study locations.

2500 2000 1500

T D A A 1000

500 0

5km after Lumino

5km before 5km before 5km from Namayingo Mayuge Busia Sation name AADT (with Motorcycles)

5km from Musita

5km before Lumino

AADT (without motorcycles)

Figure 2: Base year traffic composition at each of the study locations .

The proportion of motorcycles to the other traffic is high as seen from Figure 2. Appendix 2C contains details of the estimated AADT at each of the locations along the project roads.


14

2.3.5

Traffic Growth

In order to estimate the AADT in the project period, the Consultant needed to determine the traffic growth rate over this period. This growth is represented by a growth in normal traffic, diverted traffic and generated traffic. 2.3.6

Growth in normal traffic

To derive growth in normal traffic, analysis of either historical traffic data over the years or traffic proxies can be used. Deriving traffic growth from traffic data involves analysis of the growth of the various traffic classes over a long period of say 10-20 years. This growth will give a trend in the growth of traffic over the years. This trend is then used to project the traffic growth in the project period. It was noted that analysis of historical data was not feasible as there was no adequate historical data. Traffic growth using traffic proxies involves the comparison of traffic growth with proxies such as fuel consumption, vehicle registration trends, GDP growth etc. Appendix 4D shows the trends in growth of the various traffic proxies as well as the derived traffic growth trends. 2.3.7

Diverted Traffic

It was assumed that no traffic would be diverted from the alternative road since the project road was longer in distance than the alternative road. 2.3.8

Generated traffic

Generated traffic is additional traffic which will occur in response to the provision or improvement of a road. This will in the short term arise from increased number of trips of existing vehicles or generation of new trips which were never present before the improvement of the road. In the long term the traffic generation will be due to increased economic activity along the project road after it has been improved / upgraded. Derivation of generated traffic is shown in Appendix 2D. These factors were used in the derivation of generated traffic at the various study locations. 2.3.9

Projected Traffic growth

It was assumed that road construction shall commence in the year 2011 and end in 2015. Projections were made for a design period of 15 years and 20 years. Therefore projections were made up to the year 2030 and 2035 using the corresponding growth factors. Results obtained are shown in Appendices 2E.


15

2.3.10 Origin/Destination Surveys

OD Survey Locations Table 5 shows the locations used for the survey. Table 5: Origin Destination Survey Locations Station no . 1 2 3

OD stations, Motor ized traffic

OD station, Non mot orized traffic

5Km from Musita (Bufulubi) 5km before Busia (Dabani) 5Km from Namayingo (Buyima)

At these locations, a 7 day - 12 hour Origin Destination Survey was conducted. Data Collection and Compilation The OD survey was carried out during the month of April 2010 using enumerators hired and trained from along the project road. Information gathered through road side interviews of vehicle drivers was analyzed to understand the origin-destination characteristics of traffic plying the project roads. Since these interviews were conducted on a sample of vehicles, the collected information was expended to reflect the total volume of traffic plying on the road on that particular day. To analyze the traffic interactions between the various sub-regions of the country and outside of it, the spatial delineation of the entire region is needed for convenience of analysis. For this study, it was felt that the district/sub county boundaries would be a convenient unit of spatial delineation as each district/sub county has documented information about its demographic and socio-economic indicators. Station 1: 5km from Musita (Bufulubi) a. Trip Frequency

Figure 3 shows the frequency of trips made through 5 km from Musita


16

100%

e d a m s p i r t f o t n e c r e P

90%

Several times a day

80%

Once per day

70%

Several times a week

60%

Once a week

50%

Several times a month

40% 30%

Once a month

20%

Several times a year

10%

Once a year

0%

Rarely

Vehicle type

Figure 3: Frequency of trips made through 5 km from Musita

As seen in Figure 3, Lorries capacity > 3.5 tons and motorcycles make several trips a day while the large buses make one trip per day through the study point. b. Trip purpose

Figure 4 shows the purpose of trips made through the study point. As noted in Figure 4, most of the trips are made for business while the least trips are made for Leisure/Social purposes.

s p i r t f o e g a t n e c r e P

100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0%

To/from Home To/From Work To/From School Business Shopping Government / Official Leisure / Social Tourism Other

Vehicle type

Figure 4: Purpose of trips made through 5km from Musita .


17

c. Vehicle occupancy

Observed passenger occupancy in various types of vehicles plying through the study location is shown in Figure 5. 80 s r 70 e g 60 n e s 50 s a p f 40 o r 30 e b m 20 u N 10

0

Vehicle type

Figure 5: Observed passenger occupancy per vehicle passing through the study location

It was noted that both the medium buses and the large buses provide motorized transport along the project road. Station 2: Dabani (5km before Busia) a.

Trip Frequency

Figure 6 shows the frequency of trips made to through the study point. 100% e 90% d 80% a m 70% s p 60% i r t e 50% g 40% a t n 30% e c r e 20% P 10% 0%

Several times a day Once per day Several times a week Once a week Several times a month Once a month Several times a year Once a year Rarely

Vehicle type

Figure 6: Trip frequency at 5km from Busia


18

As can be seen from the Figure 6, Lorries and motorcycles make several trips a day b. Trip purpose

Figure 7 shows purpose of trips made through the study location.

s p i r t e g a t n e c r e P

100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0%

To/from Home To/From Work To / From School Business Shopping Government / Official Leisure / Social Tourism

Vehcile type

Other

Figure 7: Purpose of trips made through the study location

From Figure 4.6, the greatest percentage of trips is made for Business followed by to/from work or home. The least trips are made for Tourism and Leisure/Social. c.

Occupancy of Vehicles

Figure 87 shows the observed passenger occupancy in various types of vehicles passing through the study point.


19

50 s r 40 e g n e s s a 30 p f o r e b 20 m u N

10

0

Vehicle type

Figure 8: Average Vehicle Occupancy for vehicles through study point

Vehicle occupancy at this station is lower than that at 5km from Musita. It can be concluded that

 Lorries and motorcycles make several trips a day while the large buses make one trip per day through the study point,  Most of the trips through the project road are made for business while the least trips are made for Leisure/Social purposes.  Small buses, medium buses and the large buses provide motorized transport along the project road. Station 3: 5km from Namayingo (Buyima) NMT a.

Trip Frequency

Figure 9 shows the frequency of trips made to through the study point. Trips by Non motorized traffic are mostly made several times a day and once a day.


20

100% 90% e d 80% a m 70% s 60% p i r t f 50% o t 40% n e 30% c r e P 20% 10% 0%

Several times a day Once a day Several times a week Once a week Several times a month Once a month Several times a year Once a year Bicycle

Pedestrian

Cart

Rarely

Vehicle type

Figure 9: Frequency of trips made through the study point .

b.

Trip purpose

Figure 10 below shows the purpose of vehicles moving along the project road.

e d a m s p i r t e g a t n e c r e P

100%

To/from Home

90%

To/From Work

80%

To/From School

70%

Business

60% 50%

Shopping

40%

Government / Official

30%

Leisure/Social

20%

Tourism

10%

Other

0%

Bicycle

Pedestrian

Carts

Vehicle type

Figure 10: Purpose of Non Motorized vehicles moving along the project road

From Figure 10, the greatest percentage of the Non motorized vehicle trips are made for the Business (45%) and to/from home trips (24%). There are no trips made for tourism. Other information derived from this survey included the following;

 Origin and Destination characteristics  Cargo type  Traffic generating zones  Passenger origin and destination | FINAL Detailed Design Report_Rev.1-AUG.2012 |

21

 Passenger trip frequency  Passenger trip purpose  Passenger employment Appendix 2F contains a summary of the results obtained from this study.

2.3.11 Axle Load Survey

Survey Methodology A three day traffic axle load survey and counts was carried at Nabigingo out along the project road between 6 th May and 22nd May 2010. Weighing was done for both directions simultaneously using a portable weighbridge to Transport Research Laboratories (TRRL) specifications. The vehicles weighed were: I.

Medium Buses

II.

Large Buses

III.

Medium Goods Vehicles

IV.

Heavy Goods Vehicles.

V.

Very Heavy Goods Vehicles

Data Collection and Compilation The axle load survey was carried out during the month of May 2010 using enumerators hired and trained from along the project road. These were assisted by trained axle load equipment operators. The logistics and supervision of the surveys were managed by a Traffic Engineer. The traffic of eligible vehicles along the project road is not high to warrant sampling. All vehicles eligible were thus weighed. Equivalence Factors The axle load so obtained was used to calculate Equivalence Factors (E.F.) using Liddle's formula as follows: E.F = (L s /8200)4.5 ……………………………………………..........1

In computing the average equivalence factors for each vehicle type, each two lane was considered separately. Tables 6 and 7 show the summary of axle load for each direction respectively.


22

Table 6: Axle load for Vehicles from Musita Vehicle category

Av erage gro ss weight

Av erage equi valen ce factor (80KN)

Total vehicles

LGV (1.2)

4.26

0.07

22

MGV(1.2)

4.10

0.00

1

Total

23

Table 7: Axle load for vehicles to Musita Vehicle category

Av erage gross weight

Av erage equivalence factor (80KN)

Total vehicles

LB 1.2

14.68

1.69

6

LT 1.2

5.38

0.11

18

MB 1.2

4.77

0.01

3

MT 1.2

18.65

9.61

1

Total

28

2.3.12 Overloading

Figures 11 and 12 show the level of overload for the vehicles weighed at this station.

Figure 11: Level of overload from Musita


23

Figure 12: Level of overload to Musita

Table 8 shows the level of overload for each of the axle load configuration along this road. It is deduced that the level of overload from Busia is higher than that to Busia.

Table 8: Level of overload along Musita – Nankoma – Lumino – Busia/Majanji Ax le configuration Ax le lo ad >5 tons

Ax le lo ad >8 tons

>10 tons

To Busia

6.8

0

0

MB (1.2) MT (1.2)

0

>8 tons

>10 tons

From Busia

LB (1.2) LT (1.2)

>5 tons

0

0

91.7

25

8.3

11.1

0

0

0

0

0

50

50

50

2.3.13 Cumulative Equivalent Standard Axles (CESA)

The Cumulative Equivalent Standard Axles were estimated based on the assumed growth rates as summarized in Table 9. Table 9: Adopted Traffic Growth rates for LB, LGV, MGV and HGV Growth Scenario

20102013

20142018

20192023

20242030

20242035

Pessimistic

4.7

6.8

4.4

2.9

2.9

Realistic

4.7

8.5

5.6

3.8

3.8

Optimistic

4.7

10

6.8

4.6

4.6

It was assumed that the construction works will commence in 2011 and last for 4 years.


24

Based on these growth factors the Cumulative Equivalent Axles were determined by road section using the formula below.  =

365�(1 + ) − 1� 

Tables 10 and 11 give the equivalent standard axles in the periods 2015-2030 and 2015-2035 respectively. Table 10: Equivalent Standard axles in the period 2015-2030. Count station

Equivalent Standard Axles period 2015-2030 (x 1 mill ion) Direction A

Direction B

Pessimistic

Realistic

Optimistic

Pessimistic

Realistic

Optimistic

5km after Lumino

0.44

0.49

0.56

0.00

0.00

0.00

5km before Busia

2.25

2.57

2.91

0.03

0.03

0.04

5km

1.86

2.13

2.41

0.01

0.02

0.02

5km from Mayuge

1.86

2.13

2.41

0.01

0.02

0.02

5km from Musita

10.10

11.57

13.11

0.01

0.01

0.01

5km before Lumino

1.71

1.96

2.22

0.03

0.03

0.04

before Namayingo

Table 11: Equivalent Standard axles in the period 2015-2035. Count station

Equivalent Standard Axles p eriod 2015-2035 Direction A

Direction B

Pessimistic

Realistic

Optimistic

Pessimistic

Realistic

Optimistic

5km after Lumino

0.62

0.73

0.84

0.00

0.00

0.00

5km before Busia

3.22

3.79

4.40

0.04

0.05

0.06

5km

2.66

3.13

3.64

0.02

0.02

0.03

5km from Mayuge

2.66

3.13

3.64

0.02

0.02

0.03

5km from Musita

14.43

16.98

19.73

0.02

0.02

0.02

5km before Lumino

2.46

2.89

3.35

0.04

0.05

0.05

before Namayingo

2.3.14 Summarized Road Usage

Estimated Number of Passengers using the Road This was estimated from the Average Annual Daily Traffic (AADT) and the average vehicle occupancy. Table 12 shows the number of passengers passing through the study locations using motorized transport per day. Table 12: Passengers passing through the study locations (using motorized transport) per day Study location

Passengers day

5km from Musita 5km before Busia

4,177 4,076


per

25

It is noted that there are more passengers moving the 5km from Musita that 5km from Busia. Estimated Cargo Tonnage using the Road This was estimated from the Average Annual Daily Traffic (AADT) as determined during the traffic survey and axle load weight less the tare weight as determined from the axle load survey. Figure 13 shows the cargo passing each study location along the project roads per day.

1,600

s 1,400 e n 1,200 n o t , 1,000 y a d 800 r e p 600 o g 400 r a C 200 0

5km from Musita

5km from Mayuge

5km before Namayingo

5km before Busia

Station name

5km after Lumino towards Majanji

5km before Lumino

Figure 13: Cargo passing through each study point along the project roads

2.3.15 Sensitivity Analysis

As part of the ToR, for the final pavement design, the Consultant was required to; 1.

Increase the design axle load by 5% or more if historical and present overload data does not indicate a progressive tightening of overload controls.

2.

Carry out a sensitivity analysis on the axle load and traffic ADT variation (+/-5%, +/-10% and +/-40%) and assess how this affects the pavement designs.

Appendix 2G shows results from the analysis.


26

2.4

Soils and Materials Investigations

2.4.1

General

The materials investigations were conducted in accordance with the Terms of Reference. It consisted of site reconnaissance, field exploration and analysis of the findings of the field exploration .

The Draft Final Soils and Materials Report has been produced as a separate Volume. The following is the summary. 2.4.2

Sub-grade Soil Investigation

The sub-grade soil investigation along the existing road alignment comprised subgrade soil sampling by means of trial pits, DCP testing and laboratory testing. Trial Pits Trial pits were excavated at two (1) kilometre interval on alternate side of the carriageway to depths of generally 1 m. The pits were dug to varying depths from the surface to sub-grade level with a total of 180 pits dug over the total road length of the five project roads of 365 km. The vertical profile of the pavement in each trial pit was recorded and representative sub-grade sample taken for laboratory testing. The trial pit logs are included in the Soils and Materials Report. DCP Investigations DCP tests were conducted at intervals of 500m as stipulated in the ToR to measure the in-situ bearing strength (CBR) of the sub-grade. Standard DCP apparatus with the following parameters was employed:

 570mm dropping height  8 kg falling weight  60˚ tipped cone having 20mm diameter To avoid weak spots (thin layers) from being overlooked and to identify layer boundaries fairly accurately, readings were taken at 1-5 blow intervals, depending on the rate of penetration. Swamp Investigations There are no major swamps along Musia-Lumino/Busia-Majanji roads. 2.4.3

Gravel and Hardstone Sources 

Field Exploration The field exploration for this project consisted of:

- Assessment of the suitability and extent of the material source. - Excavation of trial pits. - Logging of the layers encountered. | FINAL Detailed Design Report_Rev.1-AUG.2012 |

27

- Retrieval of samples for laboratory testing. - Backfilling of the trial pits. At each site, trial pits were excavated and depths of overburden and gravel were logged. In some instances, material was sampled from rock outcrops, talus, or existing quarries, in which cases, test pit excavation was not required. The volumes of both overburden and gravel were also estimated. Gravel and Hardstone Sources



A total of 20 existing or potential gravel sources and 3 rock sources were identified and investigated along Musita-Lumino/Busia-Majanji road as listed below: Table 13: Borrow Pits and Quarries

Road No.

Road/Link Name

No. of Borro w Pits

No. of Quarries

E1.1

Musita – Lumino

13

2

E1.2

Busia – Majanji

7

1

TOTAL

20

3

The location of the materials sources are included in Appendix 3. 2.4.4

Laboratory Testing

Mobile Laboratory As a requirement under the Contract, the Consultant fabricated a mobile laboratory in a 40-foot container at its offices in Kampala. Upon completion of fabrication and fitting out the laboratory was transported and erected at the compound of UNRA’s regional offices in Jinja. Testing 

Gravel Samples

Samples of sub-grade material recovered from trial pits and samples from the gravel sources were transported to the mobile laboratory in Jinja where they were subjected to the following tests: - Natural moisture content determination - Particle size analysis - Atterberg limits - Moisture content – Dry density relationship (BS 1377 test method) - CBR (4-day soak compacted at 90%, 95% and 98% MDD) - Swell tests | FINAL Detailed Design Report_Rev.1-AUG.2012 |

28



Rock Samples

During the detailed design stage one potential quarry from each of the five project roads was drilled down to 15 m. Along Musita-Lumino road, there is an existing commercial quarry at Km 2+600 at Lugolole. Besides a sample from a stockpile of existing crushed aggregate, a hole was drilled down to 15 m. Sample of the crushed aggregate and the rock core from the drilled hole were taken to the Ministry of Works’ central testing laboratory at Kireka where they were tested for: - Specific Gravity - Ten Percent Fines Value (TFV) - dry - Ten Percent Fines Value (TFV) – wet - Water adsorption - Sodium Sulphate Soundness - Bitumen affinity The test results are included in the Soils and Materials Report. Summaries of the results are given in Appendix 3.

2.5

Hydrolog ical Studies

2.5.1

Objectives

The objectives of the services as per the terms of reference (TOR) issued to the Consultants are: 2.5.2

General Objective

 To undertake hydrological and hydraulic assessment for the project roads under Lot E  To prepare Hydrological Reports as per the Terms of Reference 2.53

Specific Objectives

 Collect and compile hydrological data for the project roads  Carry out hydrological analysis for various drainage basins and channels traversed by the road,  Computation of design discharges for the existing and proposed drainage structures along the roads  Preparation of hydrological report for the project 2.5.4

Background

A detailed hydrological study of LoT E roads was carried out in accordance with the Road Drainage Design Manual (RDDM) - Vol. 2: Drainage Design procedures | FINAL Detailed Design Report_Rev.1-AUG.2012 |

29

and methodologies including other hydrological analysis methods. Among the available methods in the RDDM, the TRRL East African Flood Model and Flood Frequency Analysis Methods (Log-Pearson III Distribution) have been considered to be the most appropriate methods given the available data. 2.5.5

Hydrological Analysis – Criteria and Practices

The Road Drainage Design Manual (2005) guidelines require a designer to develop a clear understanding of the existing drainage conditions for a given assignment before determining the capacity of the existing cross and lateral drainage structures. Among the initial understandings is the production of a concept map illustrating the drainage system, catchment delineation and existing utilities during the investigation. The manual suggests a wide ranging number of methods that can be adopted to determine the design discharges for drainage design based on the circumstances encountered. It is required that the choice of return period to be selected for the design of drainage structures should be made by the designer in relation to cost of facility, risk associated with damages associated with large events etc. Minor drainage structures e.g. side ditches are to be designed to carry a 10-year flood while major ones must be evaluated for the 25-100 year storm. The RDDM (Table 3.2) suggests suitable return periods for various structural categories. Whenever possible, it is required that adequate openings are provided to limit backwater effects and excessive bed scour. The TRRL East African Model has been widely applied and found to be more relevant in East Africa since a number of small catchments were extensively studied prior to establishing the required parameters for its application. 2.5.6

Hydrological Analysis – Methodology

In undertaking the hydrological study and analysis, the following operations are undertaken: (a) Visual inspection and capacity assessment of all existing cross drainage structures (b) Review, collection and analysis of all existing data including rainfall and runoff records (c) Catchment area delineation (d) Catchment characteristics determination (e.g. quantification of key catchment parameters - catchment area, mainstream length and slope for all existing and proposed road crossings) (e) Analysis of rainfall and flow data (f) Selection of hydrologic procedure (e.g. determination of TRRL design parameters (soil cover, land use, etc.) in accordance with the provisions of the Road Drainage Design Manual (g) Return period adoption | FINAL Detailed Design Report_Rev.1-AUG.2012 |

30

(h) Peak flow or discharge estimation 2.5.7

Data Collection

The following data sets were collected during the fieldwork in Uganda and some had already been collected and compiled for the project. (a) Topographic Maps of scale: 1:50,000 and 1:250,000: [Source: GIS Database SMEC Office in Uganda] (b) Meteorological data: [Source: Ministry responsible for Meteorological data in Uganda] (c) Hydrological and Flood Flow Data: [Source: Ministry responsible for Water Resources] (d) Uganda Soil Map of scale 1:1,500,000: [Source: SMEC Office in Uganda] (e) Digital Elevation Model (DEM): [GIS Database - SMEC Office in Uganda] (f) Site visit inspection and assessment information 2.5.8

Topography, Catchment Area Delineation and Watershed Parameters

To investigate the information and data, the essential items like relief type, catchment parameter or the streams along the route, data pertaining to roughness and runoff coefficients, topographic maps, land use and land cover, soil and geomorphology maps, the field visit inspection and assessment were used. In the study of the watershed characteristics, extensive study has been done using topographic maps (1:50,000) for all the watercourse catchments draining across the roads. The catchment areas have been delineated from the topographic maps and Digital elevation model (DEM) for Uganda. The process includes the digitization of the stream networks from topographic map, and georeferencing to UTM coordinate system, datum Arc 1960, Spheroid 1880. The DEM for Uganda and the digitized river networks are then uploaded in the ArcHydro tool in ArcGIS 9.3 to delineate the watersheds. The GPS location for the various roads drainage crossings as determined during field visit are uploaded and superimposed on the delineated watersheds. Further onscreen digitization is done to clearly define the watersheds to respective road drainage points followed by determination of catchment parameters such as area, catchment length and slope, length of mainstream from the remotest point to the crossings, elevation differences and stream slope. The four Districts of Mayuge, Iganga, Bugiri and Busia have two main drainage systems of Lake Victoria and Lake Kyoga. The Lake Victoria drainage system consists of Lake Victoria, River Nalioba, Nasigombe-Nalwire- Hone and Sango-Sio. The Lake Kyoga drainage system is constituted by River Lumboka and River Malaba wetland system. Other wetland | FINAL Detailed Design Report_Rev.1-AUG.2012 |

31

systems can be traced in Mayuge District such as Lumbuye wetland system in Mpungwe Sub County and Kyankuzi wetland system in Baitabongwe Sub County. The small streams inform of swamps and marshes cutting across the project road feed into these wetland systems. The area can therefore be summed as having wetlands and several networks of swamps. There are both surface and underground water sources, wetlands and rivers forming part of the boundaries between villages, Sub Counties and/or Districts in form of valleys. (Busia District Local Government Three Year Development Plan 2008/9-2009/10). 2.5.8

Watershed Characteristics

General Characteristics The watersheds draining to project road have distinct characteristics largely due to their geographical location, climate and land use characteristics. The relatively common aspect is that the watersheds are intensively cultivated, human settled and predominantly rolling. The Musita-Lumino/Busia-Majanji roads are characterized by:

 Natural vegetation similar to tropical forest/ grassland.  Swampy areas  Tropical climate with rainfall having two seasons i.e. from March to June and from September to November (Bimodal)  Agriculture (sugar canes, maize, cassava, sweet potatoes, millet and sorghum), Cattle rearing and mining like gold, uranium, iron core, lake sand and oil. The delineated catchments are given in Appendix 4. Soil Type According to Uganda Soil Map, the soil type of the project area are characterized as Ferrallitic soils (sandy loam and sandy clay loams) especially in lowland areas, Ferrisols, Humid Ferrallitic and Halomorphic soils in areas surrounding Mt. Elgon. The soils covering most of the project area are mainly loamy and sand loams with spots of clay at the valley areas. These soils have fine texture with rather loose structure, which are easily eroded and leached. The soil types can be summarized as;

 Yellow-red sandy, clay loam soils varying from dark grey to dark. These occur on gently undulating –hilly topography.  Brown yellow clay loams with laterite horizon with a variety of dark brown to dark grayish brown. These occur on flat ridge tops or as of undulating topography.  Light –grey- white mottled loamy soils with laterite horizon ground, structuresless loamy sands. These are acidic-allocative and mainly found on lower and bottom slopes.  Clay soils are limited to the swamps in the valleys. (Busia District State of Environment Report, 2005 and Bugiri District Development Plan 2009/10-2011/2012). | FINAL Detailed Design Report_Rev.1-AUG.2012 |

32

Climate Uganda has a typically tropical climate with little variation in temperature throughout the year. Distinctive wet and dry seasons characterize the climate of Uganda. Uganda's equatorial climate provides plentiful sunshine, moderated by the relatively high altitude of most areas of the country. Mean annual temperatures range from about 16°C in the southwestern highlands to 25°C in the northwest; but in the northeast, temperatures exceed 30°C about 254 days per year. Daytime temperatures average about eight to ten degrees warmer than nighttime temperatures in the Lake Victoria region, and temperatures are generally about fourteen degrees lower in the southwest. Except in the northeastern corner of the country, rainfall is well distributed. The southern region has two rainy seasons, usually beginning in early April and again in October. Little rain falls in June and December. In the north, occasional rains occur between April and October, while the period from November to March is often very dry. Mean annual rainfall near Lake Victoria often exceeds 2,100 mm, and the mountainous regions of the southeast and southwest receive more than 1,500 mm of rainfall yearly. The lowest mean annual rainfall in the northeast measures about 500 mm. Temperature Available temperature data for the project area have been collected. Figure 7.1 provides the monthly Minimum, Maximum, and Average Temperature for the Jinja Meteorological Station.

35.0 30.0 ) C o 25.0 ( e r u t 20.0 a r e p 15.0 m e T r 10.0 i A

5.0 0.0

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Max.

29.1

30.1

29.1

28.1

27.6

27.3

27.4

27.9

28.4

28.7

28.3

28.3

Min.

17.0

17.4

18.0

17.9

17.7

17.1

16.4

16.4

16.8

17.2

16.9

16.6

Mean

23.1

23.7

23.6

23.0

22.6

22.2

21.9

22.2

22.6

22.9

22.6

22.5

Figure 14: Mean Monthly Maximum, Minimum and Average Temperature at Jinja Met. Station for the period (1999 – 2008)

Rainfall Available rainfall data for the study area have been collected from the Department of Water Resources in Uganda. Table 14 presents the mean monthly rainfalls at the Jinja and Ikulwe stations. | FINAL Detailed Design Report_Rev.1-AUG.2012 |

33

These rainfall stations were considered to have data of sufficient length that are important in deriving statistical information for the determination of the design rainfall at specific recurrence interval, covering a period of 39 and 22 years, respectively. Table 14: Mean monthly rainfall (mm) Months

Station

Jan

Feb

Mar

Apr

May

Jun

Jul

Jinja

75.9

70.2

144.4

190.7

143.6

64.1

64.6

Ikulwe

63.1

55.4

119.7

151.1

127.0

83.1

56.9

Aug

Sep

Oct

Nov

Dec

Total

97.6

108.9

123.0

153.8

85.5

1322.2

84.6

78.1

115.1

138.2

111.6

1184.0

Table 15 presents the maximum daily (24-hours) rainfall at the six stations. These rainfall stations were considered to have data of sufficient length that are important in deriving statistical information for the determination of the design rainfall at specific recurrence interval. The records for Jinja and Ikulwe cover 39 and 22 years respectively. Table 15: Maximum daily rainfall data (mm) Jinja Year Rainfall Year Rainfall 1960/61 1982/83 56.5 1961/62 1983/84 43.0 1962/63 1984/85 83.0 1963/64 1985/86 60.5 1964/65 1986/87 54.9 1965/66 1987/88 29.7 1966/67 1988/89 43.8 1967/68 1989/90 79.6 1968/69 1990/91 70.8 1969/70 87.4 1991/92 40.8 1970/71 89.8 1992/93 53.7 1971/72 101.3 1993/94 76.6 1972/73 69.9 1994/95 116.7 1973/74 46.4 1995/96 112.1 1974/75 60.5 1996/97 39.9 1975/76 111.0 1997/98 78.6 1976/77 72.9 1998/99 117.5 1977/78 60.4 1999/00 73.2 1978/79 67.0 2000/01 62.1 1979/80 78.0 2001/02 73.1 1980/81 68.5 2002/03 65.7 1981/82 57.6 2003/04 94.8 2004/05 99.7 2005/06 103.4 2006/07 85.1 2007/08 47.5 2008/09

Ikulwe Year 1960/61 1961/62 1962/63 1963/64 1964/65 1965/66 1966/67 1967/68 1968/69 1969/70 1970/71 1971/72 1972/73 1973/74 1974/75 1975/76 1976/77 1977/78 1978/79 1979/80 1980/81 1981/82

Rainfall 57.0 62.0 60.0 45.3 62.5 36.0

Year 1982/83 1983/84 1984/85 1985/86 1986/87 1987/88 1988/89 1989/90 1990/91 1991/92 1992/93 1993/94 1994/95 1995/96 1996/97 1997/98 1998/99 1999/00 2000/01 2001/02 2002/03 2003/04 2004/05 2005/06 2006/07 2007/08 2008/09

Rainfall 33.9 60.9 56.5 44.5 34.5 56.2 52.1 37.2 31.5 84.6 67.8 49.8 46.2 57.0 62.0 46.2

Table 16 presents the important statistics of the rainfall data from the two stations with the most reliable and long records. | FINAL Detailed Design Report_Rev.1-AUG.2012 |

34

Table16: The important rainfall statistics data Station Code Name Jinja Met. Station Ikulwe Farm Institute

89330430 89330390

Highest

Lowest

(mm) 117.5 84.6

(mm) 0.0 0.0

Mean (μ) (mm) 72.6 52.0

Stdev Coef. of () Variation (mm) (Cv) 22.7 0.3 13.0 0.3

Coef. of Skew (Cs) 0.970 0.767

300 250 ) 200 m m ( l l 150 a f n i a R

100 50 0 Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Months

Jinja

Ikulwe

Figure 15: Mean Monthly Rainfall of the stations with good rainfall records Stream flows Existence of gauged stream flow data of sufficient length (at least 10 years), permits estimates of the peak discharge in terms of its probability of frequency of occurrence by employing statistical methods. In the study area, such data are not readily available, except for Manafa River that has some gauged data spanning for 11 years (1999-2009). The yearly maximum daily flow data were extracted from the daily time series for each year and analysed to estimate the flood design discharges at a specific return period (e.g. 100 years). For un-gauged catchments, the rainfall data of the project surrounding area were used to compute design rainfall and used in the TRRL East African Food Model to estimate the design flood discharge at their corresponding delineated catchment crossing points. For catchments with no properly defined channels/streams, extrapolation of design flow was made using drainage area ratios provided the areas had similar characteristics and within the same metrological zone.


35

2.6

Swamp Investi gations The locations of swamps or marshy areas along the Musita-Lumino/Busia-Majanji roads were visited in order to provide a preliminary assessment of their likely impacts upon the design of these roads. Along Musita-Lumino road 14 no. low lying marshy areas were identified. There are no swamps along the route.

2.7

Drainage Investi gatio ns

2.7.1

Assessment of Existing Drainage Structures

A visual assessment of the drainage structures was carried out by the Bridge/Drainage Engineer and the Hydrologist. Each minor and major drainage structure was inspected and relevant basic measurements were taken. Data on hydraulic performance and history of any overtopping and history of rehabilitation measures undertaken were collected from local residents and branch of the ministry of works. Moreover, observations were made relating to:         

Hydraulic performance Physical condition Possible causes of damage Materials used for construction and their performance Period of service Possible reasons for poor performance Possibility of maintenance or repair Performance in respect to traffic safety Replacement options

A detailed photographic inventory and assessment of all the existing drainage structures are prepared following the field inspection. These schedules are included in Appendix 5A and 5B. 2.7.2

Classification of Drainage Structures

For the purpose of this project, all drainage structures are classified in two broad classes namely, minor and major drainage structures. Minor Structures Minor drainage structures are those pipes having single or multiple cell opening either made from concrete or corrugated metal sheet (Armco) and all the road side drainage facilities. Major Structures Structures included in Major Structure’s category are box culverts, slab culverts and reinforced concrete /composite/ steel / bridges.


36

Slab culverts are those with top slab resting on abutments done separately, and box culverts are those having monolithic top slab, bottom slab and the vertical walls. 2.7.3

Side Ditches

Stone pitched side channels and flow checks are found along a certain sections of the project roads. Some are recently constructed and are in very good condition. But in general it is observed that due to lack of regular repair, water flows out of the channel damaged the road pavement and make it difficult for road users. Please refer to Appendix 5A for details. 2.7.4

Pipe Culverts

According to the structures inventory data, we found out that there are over 300 existing pipe culverts along all the project routes. The majority of the existing pipe culverts are made from either reinforced concrete with internal diameter ranging from 300mm to 1000mm or Armco sheet ranging from 600mm to 2000mm internal diameter. Please refer to Appendix 5A and 5B for details. ` During assessment of the drainage structures along the project route, the following major deficiencies or problems were observed at pipe culverts:

       2.7.5

Damaged or missing headwalls Siltation in pipes due to low invert level Poor workmanship at the head walls and at pipe joints. Insufficient length of pipes as compared to the width of the road Insufficient hydraulic capacity Lack of regular cleaning Missing or damaged aprons and energy dissipaters at inlets and outlets

Box Culverts

More than six box/slab culverts are found along the entire project route. Please refer to Appendix 5A for details. The following major deficiencies or problems were observed at box/slab culverts during the assessment:

     2.7.6

Deteriorated slab concrete Cracked, damaged abutments and wing walls Insufficient hydraulic capacity Eroded bank and scoured bed. Damaged inlet and outlet aprons (either broken down or dislodged)

Bridges

All drainage structures where the top slab is exposed for direct contact to traffic wheel load regardless of their span are categorized as bridges. More than 10 bridges are identified for the entire project. The following table demonstrates the current condition of the existing bridges.


37

2.7.7

Existing Bridges

There are no existing bridges along Musita- Lumino road. 2.7.8

Summary

The following summary is made based on the assessment of drainage structures along the entire project roads. 

Drainage is a major issue along the project roads and it is the prime factor for the road damage. And almost in all cases existing drainage facilities are found inadequate.



A certain sections of the roads traverse through major flood plains and marshy areas. And in most cases these roads are over-topped during the regular rainy season.



Inadequate opening size of most pipe culverts provided, forced the placement of additional pipes by the side of the existing ones which has done little in alleviating the drainage problem but reducing the riding quality of the road.



Luck of enough cover over pipe culverts resulting either broken concrete pipes or tiered Armco pipes



Insufficient length of structures provided resulting in narrow road section



Poor overall workmanship and lack of regular maintenance



Long year of service



Inadequate structural capacity

2.8

Environm ental and Social Studies

2.8.1

General

An Environmental and Social Impact Assessment was carried out for the project roads and surrounding areas during 2010/2011, with a summary of the findings presented below. Detailed assessment of the impacts upon the project and the mitigation measures are given in the Final ESIA Report. 2.8.2

Geographic al Loc ation

The Musita-Lumino/Busia-Majanja roads are situated in the Eastern part of Uganda. They traverse four already established districts of Mayuge, Iganga, Bugiri and Busia Districts and the newly approved District of Namayingo which is to be carved out of Bugiri District.


38

2.8.3

Bioph ysical Environment

The topography of the project area is relatively flat with high ridges and isolated hills, adulating lowlands and perch vents with a few higher residual features. In terms of geology, the project area is made up of Precambrian rocks with bare granitic rocks at several places heavily eroded. The soils covering most of the project area are mainly loamy and sand loams with spots of clay at the valley areas. It has two main drainage systems of Lake Victoria and Lake Kyoga. According to Busia District State of Environment Report, 2005. The area has noted fluctuations in rainfall figures over the last seven years. In October-December 1997, Busia and the neighboring districts experienced heavy rains (El-Nino), with figures averaging ten times the normal and resulting in disastrous flooding. The mean annual maximum temperature in the project area is 28.7 0C and the mean annual minimum is 16.2 0C. The mean monthly maximum is 27 0C, while the mean minimum sometimes falls to 16 0C especially at dawn (early morning). The vegetation observed in the project area has undergone considerable changes and this can be attributed to continuous cultivation, burning or clearing for different purposes. The project road is not very rich in faunal diversity given the level of interference inflicted upon the natural vegetation; the would-be in habitats of this diversity. 2.8.4

Socio-economi c and Cultu ral Environment

According to the 2002 Population and Housing Census, the total population in the 16 Sub Counties through which the road traverses is 123,669 persons of which 59,271 are males and 64,398 are females and the average household size is 5 persons. The results indicate that the general literacy levels within the project area are very low as the majority of the households (49.6%) did not exceed primary level. The majority of the households (80.3%) along the road in all the four districts are married while 19.7% are not married. The major ethnic groups in the project area are Basoga (45.4%), Basamia (26.8%), Banyole (12.5%), Japadhola (4.4%), Iteso (3.1%), and Bagwere (2.5%). Other ethnic groups in the area include Baganda, Bagisu, Badama, Bakenye and Lugbara. As regards religion, the majority of the population in the four districts belongs to the Anglican/protestant and Moslem religions followed by Catholics. The most common land tenure system in the project area is customary. The land is comprised of farming land, settlements, manmade forests and swamps. In terms of size, the results indicate that the average land size owned by the households in the project area is 2 acres. The predominant economic activity is subsistence agriculture. The main crops grown include maize, rice, sugarcanes, bananas, cassava, sweet potatoes and | FINAL Detailed Design Report_Rev.1-AUG.2012 |

39

beans. The main cash crops are cassava, rice and sugarcanes. According to the household survey, the average monthly income for households in the project area is UGX 163,300 while the average annual income is UGX 1,908,000. Most (36%) of the households in the project area are temporary made of mud and wattle, 35.6% are semi permanent and 28.4% are permanent. Most of the permanent structures are found in trading centres. The main source of water is public boreholes 56.5%, followed by protected springs/wells (19.9%), 15.7% depend on unprotected springs/wells, 2.9% depend on privately owned boreholes. Other water sources include stand posts, valley tanks/earth dams and others buy from water vendors. 2.8.5

Predict ed Enviro nment and Social Impacts

There are several positive impacts that might accrue as a result of the upgraded the road and these include the following:          

Creation of job opportunities to the local unskilled persons as well as skilled persons in the community. Improved accessibility to markets. Easy and comfortable transportation. Improved transport and communication after construction of the road. Improved market for locally available resources needed for road construction e.g. stones, sand, gravel among others. Land value appreciation Increased retention of qualified personnel Increase beauty of the area. Increased trade between districts, regions and Kenya. Improved road drainage infrastructure and general discharge of storm water from the road/carriageway.

However a number of negative impacts were also identified as described below. Biophysical impacts will include increased noise, deterioration of air quality, aesthetics, vegetation clearing ,forest degradation in areas as in KyebandoMayuge,Mpumu and Lumino having planted forests of bamboo, pines and ornamental trees by the road side, impacts from quarrying and gravel mining activities. Social impacts identified include high social expectations, loss of structures which will include graves, about 1,561 structures which are temporary, semi permanent and permanent in nature. In addition, several institutions will also be affected through loss of land, structures and these include about 51 educational institutions, 13 health centres, and religious places among others. The acquisition of about 1,285 acres of land will lead to loss of land for many households and this will greatly affect their livelihood as the majority depends on agriculture as the main source of income. Note: The actual number of affected property will be established during the preparation of the Resettlement Action Plan. Other potential negative impacts include the influx of people especially during the construction. This will bring about an increase in the spread of sexually transmitted diseases like HIV/AIDS, syphilis, gonorrhea among others, increased stress on social services like education, water and health. Community or public infrastructure like water sources, electricity lines will be disrupted.


40

However, all the social impacts represent a potentially more serious effect of the project. All impacts of the project have however been found to be manageable provided mitigation measures which have been proposed are implemented. Table 17 below shows the predicted negative environmental and social impacts without mitigation. Table 17:Overall Impact Assessment Study

Value/vulnerability of the Environment Component

Magnitude of impacts

Overall impact Assessment (without mitigation measures)

Scale

Low/Med./High

Negative Positive High Medium Little/No Med. High

-♦Planning Phase

Social Expectations

-♦-

Land use

-♦-

-♦-

Large negative impact(---) -♦-

Medium negative (--)

Construction Phase

Employment

-♦-

-♦-

Medium positive (++)

Increased market

-♦-

-♦-


Soil erosion Installation of road furniture Aesthetic value Waste generation (soil &vegetation material and other solid waste) Potential cont. of water sources Drainage & wetlands Air quality Noise Impacts of quarry devt. Vegetation & forests Disruption of wildlife Influx of people Increased STDs & HIV/AIDS Displacement & loss of housing

-♦-♦-♦-♦-

-♦-

-♦-

Minimal/No impact (0)

-♦-


-♦-♦-

Small negative (-) Medium negative (--)

-♦-

Minimal or No impact (0)

-♦-

-♦-

-♦-

-♦-♦-

-♦-

Medium negative (--) Large negative (---) Large negative (---)

-♦-♦-

-♦-

-♦-

-♦-

Small negative (-) -♦-

-♦-

-♦-

-♦-


Minimal or No impact (0)

Minimal or No impact (0) Medium negative (--) Medium negative (--) Large negative (---)

41

Study

Value/vulnerability of the Environment Component

Magnitude of impacts

Overall impact Assessment (without mitigation measures)

Scale

Low/Med./High

Negative Positive High Medium Little/No Med. High

-♦Land acquisition Educational vulnerable groups Disruption of water supply Disruption of other infrastructure Agriculture Health and Safety other economic activities Impact on Gender

-♦-♦-♦-♦-

Large negative (---) Medium negative (--) Medium negative (--) Medium negative (--)

-♦ -♦-♦-

-♦-

-♦-♦-


-♦-♦-

-♦-

Large negative (---) Medium negative (--) Small negative (-)

-♦-

-♦-

-♦-

Cultural Heritage -♦Operational and Maintenance (O&M) Transport & com. Staff retention Land appreciation Access to HC Loss of livelihood Community conflicts Increased Accidents Air pollution from bitumen during resurfacing Poor silt disposal

-♦-


-♦-

Small negative

-♦-

-♦-♦-♦-

-♦-♦-♦-

-♦-

-♦-♦-♦-♦-

-♦-

Large positive (++) Small positive (+) Medium negative (++) Small positive (+) Minimal or No impact (0) Minimal or No impacts (0)

-♦-

Medium negative(--)

-♦-

-♦-


-♦-

-♦-

Medium negative(--)

Details of proposed mitigation measures are detailed in the Final ESIA Report.


42

3

DETAILED DESIGN

3.1

Geometri c Design

3.1.1

Introduction

In developing the design for the upgrading of Musita-Lumino and Busia-Majanji roads, the objectives as set out in the Terms of Reference were considered in detail. A number of alignment options were developed with due regard to the following considerations;  Design manual criteria  Balance between cut and fill  Minimise land take  Affordable and acceptable accommodation works for frontages  Minimise utility protection/relocation  Avoid geological, hydrological and environmental problems  Avoid extensive and expensive bridge works  Protect vulnerable road users  Provide in-build safety measures  Provide adequate road users facilities The resulting alignment options were further assessed by our resettlement and land acquisition team and discussed extensively with the Client before a final option was approved and considered for detailed design. 3.1.2

Design Standards

The geometric design of the project road was carried out as per the guidelines contained in the Ugandan MoWH&C Road Design Manual of July 2005. This was in accordance with the requirements of the TOR, and as confirmed by UNRA. The Manual was complimented by recognized design manuals from neighboring counties including;  Kenya’s Road Design Manual – Part 1: Geometric Design Manual  Tanzania’s Draft Road Manual  Code of Practice for Geometric Design (SATCC-1998) – Trunk Road Design Standards


43

Lot E roads have been packaged into the following contracts; 1. Package 1:

Road E1.1 Musita-Lumino and Road E1.2 Busia – Majanji

2. Package 2A: Road E2.1 Tirinyi – Pallisa and Road E2.2 Pallisa – Kumi 3. Package 2B: Road E2.3 Pallisa – Kamonkoli 4. Package – 3: Road E3 Bumbobi - Bubulo – Busumbu – Lwakhakha 5. Package – 4: Road E4 Namagumba – Budadiri – Nalugugu 6. Package – 5: Road E5 Kamuli - Bukungu Package 1 comprises two links, Musita – Lumino and Busia Majanji. The Musita – Lumino link starts from Musita trading center along the Jinja-Iganga highway. It continues on an eastwards direction passing through Mayuge, Nankona, Buyinja and ends at Lumino trading center. The Busia – Majanji link commences at Busia town continuing southwards through Dabani, Masafu Lumino and ending at Majanji on the shores of Lake Victoria. The project road is an alternative link between Jinja and Busia town and also serves as a link to a number of landing sites along Lake Victoria including Majanji, Lufudu, Omenya, Wakawaka and Kigandala. From Lumino, one can also access Lwanda border post which has been earmarked for upgrading by Uganda Revenue Authority (URA). On the basis of the Design Manual, the project road can be classified as Class C or a Primary road. These are described as roads linking provincially important centers to each other or to a higher class roads (urban/rural centers). They provide linkage between districts, local centers of population and development areas with higher class road. Their major function is to provide both mobility and access A paved Class II road standard was adopted for the geometric design of the project road; the applicable geometric design standards for which are presented in Figure 4.2a and 4.2b of Section 4 of the Design Manual and reproduced below as Table 18 and Table 19 for ease of reference.


44

Table 18:

Road Design Classes Maximum Design speed

Capacity [pcu x 1,000/day]

Road-way width[m]

Ia Paved

12 - 20

Ib Paved

Design Class

Kp h Level

Rolling

Mountainous

20.80-24.60

120

100

80

6 – 10

11.0

110

100

II Paved

4– 8

10.0

90

III Paved

2– 6

8.6

A Gr avel

4– 8

B Gravel

2– 6

C Gravel

Table 19 :

A

B

80

√

√

70

60

√

√

80

70

50

10.0

90

80

70

8.6

80

60

50

6.4

60

50

40

C

D

E

√

√

√

√

Road Design Classes (continued)

Design cl ass

Right of Way width [m]

Road way width [m]

Ia Paved Ib Paved II Paved III Paved A Gravel B Gravel C Gravel

60 60 50 50 40 30 30

20.80-24.60

3.1.3

Functional Classification

11.0 10.0 8.6 10.0 8.6 6.4

Carriage w ay No. of Lane Width lane width [m ] [m ] 14.6 3.65 4 7.0 3.5 2 6.0 3.0 2 5.6 2.8 2 6.0 3.0 2 5.6 2.8 2 4.0 4.0 1

Shoulder width [m ]

Median width [m ]

2 x 2.5 2 x 2.0 2 x 2.0 2 x 1.5 2 x 2.0 2 x 1.5 2 x 1.2

1.2 – 5.0 -

Design Speed

The road sections between Musita and Lumino and Busia – Majanji has been classified as flat, having gradients not exceeding 5.5%. A design speed of 90 kph has been recommended as per the Design Manual Table 6-15. It should however be noted that many sections of the existing road are long and straight and higher speeds than these will be possible. Through the more populated centres along the route, the design speed of 90 kph has been maintained for the selection of appropriate geometric elements, however the posted speed limit of 50 kph has been set for pedestrian safety. Table 20 is a schedule of centers where it has been proposed that the traffic speed be regulated through the installation of road signage, speed bumps and rumble strips. Other centres noted along the project road and for which the


45

design speed may only be regulated by installing appropriate traffic signs are listed in Table 20 below.

TABLE 20 -

SECTIONS WITH DESIGN SPEED OF 50 Km/h REGULATED BY BUMPS AND RUMBLE STRIPS

Road E 1.1 Musita-Lumin o FROM

Km

TO

0 + 000

Km

0 + 400

LOCATION

Musita Bypass

Km 12 + 800

Km 14 + 000

Mayuge Township

Km 35 + 100

Km 37 + 500

Nankoma Township

Km 46 + 900

Km 48 + 600

Muterere

Km 50 + 500

Km 52 + 100

Bukoli

Km 56 + 500

Km 57 + 600

Namavundu

Km 62 + 400

Km 63 + 500

Buyinja

Road E1.2 : Busia-Majanji FROM

TO

LOCATION

Km

0 + 000

Km

1 + 300

Busia Town

Km

5 + 800

Km

6 + 500

Dabani

Km

7 + 800

Km

9 + 300

Masafu

Km

19 + 100

Km 19 + 600

Lumino

Km

26 + 500

Km 26 + 732

Majanji

TABLE 21 –

SECTIONS WITH 50Km/h REGULATED SPEED USING ONLY TRAFFIC SIGNS

Road E1.1 : Musita-Lumi no FROM

TO

LOCATION

Km

1 + 700

Km

2 + 600

Lugolole

Km

6 + 000

Km

6 + 500

Bufulumbi


46

Km 16 + 300

Km 16 + 800

Maina

Km 20 + 200

Km 21 + 300

Mpunge

Km 26 + 100

Km 26 + 600

Bunalwenyi

Km 30 + 100

Km 30 + 700

Bwamula

Km 32 + 700

Km 33 + 600

Itakaibolu

Km 41 + 200

Km 42 + 000

Namabingo.

Km 66 + 700

Km 67 + 300

Lunyo

Km 72 + 200

Km 72 + 500

Bwaniha

Road E1.2 : Busia-Majanji FROM

TO

LOCATION

Km 13 + 700

Km 14 + 600

Mailo Eight

Km 15 + 700

Km 16 + 100

Mailo Seven

Given these design speeds, the horizontal alignment adopted has been chosen to suit the topography and minimize overall cost, whilst the vertical alignment is very much governed by drainage requirements and the need to raise embankments at low lying areas or wetlands.

3.1.4

Design Departures

The design speed and the recommended geometric elements were adopted as much as possible, however in sections where the terrain required expensive and uneconomical earthworks or the resulting cost of acquisition became too high, design departures were recommended. As stated above both Musita – Lumino and Busia – Majanji Majanji roads can be classified as flat with a recommended design speed of 90 km/h. However along the Musita – Lumino road at Km 0+250 a horizontal curve of 200m radius has been proposed as opposed to the minimum of 320m recommended for a 90 km/h. This has been done to provide a straight approach to the main junction with adequate sight distance. This has been mitigated by recommending 50 km/h speed limit signs.

| FINAL Detailed Design Report_Rev.1-AUG.2012 Report_Rev.1-AUG.2012 |

47

Between Km 44+700 and 45+900 a steep grade of 6.7% is encountered. It has therefore been necessary to reduce the design speed at this section to 70 km/h in order to save on expensive earthworks that may be required to maintain a 90 km/h design speed over the section.

3.1.5

Cross-Section

The Road Design manual proposes a cross section of 3m lanes and 2m shoulders totaling 10m for a Design Class II Paved road. This is presented in Table 4-2b of the manual. However, in consideration of safety, the anticipated traffic growth and further consultations with UNRA, it was agreed that a cross section comprising 3.5m lanes and 1.5m shoulders in the rural areas and 2m in Urban/Trading areas be adopted for the project road.. Additional Additional separated Service Lanes and Pedestrian walkways walkways have been proposed at locations given in Table 22 below: TABLE 22 – SECTIONS WITH PEDESTRIAN WALKWAYS

FROM

3.1.6

TO

LOCATION

Km 12 + 800

Km 14 + 000

Mayuge Township

Km 35 + 100

Km 37 + 500

Nankoma Township

Km 46 + 900

Km 48 + 600

Muterere

Km 50 + 500

Km 52 + 100

Bukoli

Km 56 + 500

Km 57 + 600

Namavundu

Embankment Design

In order to reduce earthworks and shoulder works to a minimum, the following embankment slopes have been proposed  for fill height hf < 1 m = 1:4 (vertical:horizontal)  for fill height hf > 1 m = 1:2  for cut height hc < 1 m = 1:2  for cut height hc > 1 m = 1:2


48

It should be noted, however, that such an approach does have safety ramifications. From a safety perspective side slopes of 1 in 6 for embankment are recommended to reduce the likelihood of vehicle overturning. In terms of stability, a slope of 1 in 2 is stable for the embankments heights proposed for the project. The steeper slopes tend to perform better in terms of erosion, as the quantity of water landing on the slope during rain is less. The water running off the road clearly travels faster down the slope and causes an erosion channel, probably more so than on a flatter slope. Where this occurs, chutes are to be provided to cater for the run-off. It has also been recommended that the pavement layer construction should be extended to cover the full width of the shoulders in order to meet the following principal objectives: (a) to enable heavy goods vehicles to pass each other safely making use of the full road width; (b) to make provision for the high level of of cycle and pedestrian pedestri an traffic along along the project road; and (c) to prevent damage to and erosion of the shoulder and carriageway carriageway edge. 3.1.7

Adopted Design Parameters and Standards

The following parameters and standards have been adopted in the designs:

Design Design life:

20 years.

Cross-section:

7.0 m wide carriageway at 2.5% normal camber (3% at flat sections) 2.0 m wide shoulders at 4.0 % normal crossfall 1.0 m wide side drain.

Desi Desi gn Speed Speed Parameters: Parameters: Design Speed Speed

90 Km/h

70 Km/h

Min. Horizontal Radius

320 m

185 m

Max. Superelevation Max Gradient (Absolute)


7% 5.5%

7.5%

49

Rate of Change of Superelevation

0.4-0.6 max

Minimum Crest Curve Kmin (stopping sight distance)

71

31

90 Km/h

70 Km/h

41

25

Stopping Sight Distance (SSD)

170 m

111 m

Passing sight Distance

750 m

550 m

Design Speed

Minimum Sag Curve Kmin

3.1.7

Summary of Adopted Design Speeds

Musita – Lumino:

Km 0+000 – 44+700: Flat terrain - Design speed = 90 km/h Km 44+700 – 45+900: Rolling terrain – Design speed = 70 km/h Km 45+900 – 77+140: Flat terrain – Design speed = 90 km/h Busia – Majanji:

Km 0+000 – 26+811: Flat terrain – Design speed = 90 km/h

3.1.8

Design Road Alignment

3.1.8.1 General

The geometric characteristics of the existing road alignment were obtained from ground data capture generated from aerial photography surveys. During this exercise, control points were established alongside the road. This data was ultimately tied onto the National grid system. Ground data capture was generated at 5 m square grids and covering a corridor of 35m either side of the existing centreline. This data was then imported into AutoCAD Civil 3D software to generate a digital ground model of the route corridor. A geometric record of the plan and profile of the existing road, both for the assessment and creation of a model to act as the basis for the alignment designs were then carried out.


50

3.1.8.2 Selection of Alignment

The following principles were adopted during selection of the appropriate alignment for the preliminary design: 

Conformity t o the s pecified geometric design parameters.

The alignment was designed to conform to or surpass the geometric design parameters as recommended in the design manual. 

Follow the general corridor of the existing road.

The general approach to the route alignment was to use the corridor of the existing road as much as possible. This was done to retain the present social function with minimum disruption to existing and long-term residents. Minor realignments were however introduced to improve the road geometry and remove potentially dangerous curves. This was also done at locations of new bridges. 

Keep the works w ithin th e existi ng rig ht of way.

In most sections, the alignment design was carried out to follow the existing road as much as possible to enable the use of existing pavement materials to form new a subgrade. 

Improve junctions.

In order to improve safety at the approach junctions, the project road has been realigned to approach the main highway at a right angles. 

Re-align at trading centres.

There are a number of large trading centers along some of the project roads with heavy population and agricultural activities. The possibility of having a bypass at some of these centers was investigated. Preliminary realignments outside the centers were designed. These were then presented to the Resettlement and Land Acquisition specialist who also visited the project road to evaluate the impact of the bypasses against keeping the alignment through the centers, compensating where necessary and maintaining the current social function of the road. A section-by-section description of the existing road features and proposed realignments follows.

3.1.9

Alignment Details

3.1.9.1 Road E1.1 : Musita-Lumino

(A)

Horizon tal Alignm ent


51

(1)

Realignment of the junction at Musita (Km 0 + 000 to Km 0+400)

The project road joins the Jinja – Iganga highway at a skew angle. The taxis stop at the junction to pick up passengers and despite the provision of deceleration and acceleration lanes, the junction still remains a safety hazard. In order to improve safety at the approach junction, the following solution has been proposed: 

The project road has been realigned to approach the main highway at a right angle with the junction some 200m from the existing junction;



Care was taken to locate the realignment where there would be minimal compensation and affected buildings;



A 6 m wide service road with 1 m shoulder has been proposed for Musita trading center, however to restrict motorist from joining the main road through this access road it has been proposed that it be blocked at the current junction by constructing a deep lined-side drain.



A right-turn lane has been provided to enable safe maneuver of heavy goods vehicles. Acceleration and deceleration lanes have also been provided and appropriate taxi-bays.

(2)

End of Musita Bypass to the start of Lumino Bypass (Km 0+400 to Km 76 + 400)

The existing alignment along this section of the road is generally has long straights with gentle curves. A roundabout has been proposed at Mayuge Km 13+166 to improve the traffic flow at the four intersecting roads. Mayuge A bypass was initially proposed between Km 12+800 to 15+100. A review of the proposed bypass by the Resettlement and Land Acquisition Specialist revealed that it impacted a health center at Km 12+800 together with several buildings, a mosque and a church at Km 13+400 and a heavily populated area with homesteads and cultivated land. It was agreed that the alignment be passed through the available 25m ROW through the center, set the Right of Way at 30m and at least compensate for the affected structures on one side. Nankoma A bypass was proposed from Km 34+750 to 37+200. It was found to impacted Nankoma Primary school, Nankona HC-IV including a new outpatient department as well as buildings and cultivated land. After confirming that the existing road corridor within the town was between 22 to 29m, it was agreed that the centreline be passed through the town and affected structures be compensated.


52

Namavundu The proposed bypass at this center was between Km 56+100 to 58+100. It was found to impact Kifuyo CoU Primary School as well as a church and many homesteads. The existing road corridor within the town was found to vary between 24 to 30m. It was therefore agreed that the alignment be passed through the town and after fixing the ROW at 30m, the affected structures be compensated. (3)

Lumino By-pass (Km 76 + 400 to Km 77 + 129)

The existing road through Lumino trading center is very narrow and inappropriate for the anticipated high volume of traffic and pedestrian safety. A bypass has been proposed to connect to the Busia – Majanji road at a right angle improving the visibility splay at the junction and road user safety. A roundabout has been recommended for this junction to provide a link connecting to the existing Lumino-Lwanda road. A service road comprising 6 m carriageway and 1 m shoulders have been proposed to serve the shops and the business community at Lumino. (4)

Lwanda Link Road

A link road connecting to the existing Lumino – Lwanda road from the end of the Musita – Lumino road has been proposed. This is in anticipation of the soon-to-be expanded Lwanda border post. (B)

Vert ical Alignm ent

The terrain along the Musita – Lumino road can be classified as follows; 

Km 0+000 – 44+700: Flat – Recommended design speed = 90 kph



Km 44+700 – 45+900: Rolling – Recommended design speed = 70 kph



Km 45+900 – 77+140: Rolling – Recommended design speed = 90 kph

The digital terrain model (DTM) generated from survey data was used to produce the existing ground profile along the centreline of the horizontal alignment. A vertical alignment was then designed to comply with the recommended design speeds and the vertical profile parameters as provided for in the Geometric Design Standard for Type II paved road. (C)

Gradients

Km 0+000 – 44+700


53

The terrain between Km 0+000 and 64+000 of the project road is generally flat with gradients between 0.0 and 5.2%, however the section from Km 44+780 and 45+880 has a steep drop with a gradient of 6.7%. This is still within the recommended maximum gradient for rolling terrain. Km 44+700 – 45+900 The section has a steep drop of 6.7% grade and can therefore be classified as rolling. This has necessitated a design departure as earlier discussed. Km 45+900 – 77+140 The road section between Km 45+900 and 73+700 is generally flat with gradients ranging between 0.5 and 5.0%. 3.1.9.2 Road E1.2 : Busia-Majanji

(A)

Horizon tal Alignm ent

No major realignment has been proposed for this road. The existing alignment has gentle curves which accommodated the design parameters. A roundabout has been proposed at the start of the project along the Busia – Iganga road to control the traffic flow from the border post, Tororo and Iganga. A second roundabout has been proposed for the junction at Lumino to control the traffic to Lumino center, Majanji and Lwanda. At Majanji the administration had earlier requested the design consultant to consider extending the project road upto the existing landing site which has recently been rehabilitated. On subsequent discussions with UNRA, it was agreed that the request be considered. The road section ends at Km 26+847. (B)

Vert ical Alignm ent

Km 0+000 – 26+847 As mentioned before, the terrain over this road section is generally flat with gradients ranging from 0.0 to 4.1%. Details of the horizontal and vertical alignment design for the entire project are presented in 3.1.10 Low Lying Area

The project route traverses substantial stretches of lowlying areas nd marshland. The upgraded road has been designed to have an embankment


54

height of at least 2.5 m in height to minimize the effects of water rising up beneath the sealed pavement through capillary action. The embankments supporting the existing gravel surfaced road are generally only one to one and a half metres in height. The wetlands and low lying areas were noted at the following sections of Musita – Lumino road:

From Km

To Km

Length (m)

DESCRIPTION

4 + 900

5 + 200

300

Marsh

6+650

7+350

700

Marsh

10+400

10+600

200

Marsh

15+800

15+950

150

Marsh

18+700

18+900

200

19+600

19+800

200

Marsh

21+050

21+150

100

Marsh

22+250

22+400

150

Marsh

23+700

24+200

500

Marsh

28+550

28+870

150

Marsh

34+100

34+600

500

Marsh

37+650

38+050

400

Marsh(Rice Paddies)

40+000

40+400

400

Marsh(Rice Paddies)

54+050

54+150

100

Marsh

54+800

54+950

150

Marsh

Swamp(seasonal)

SOIL TYPE

Silty/Sandy Clay Silty/Sandy Clay Silty/Sandy Clay Silty/Sandy Clay Silty/Sandy Clay Silty/Sandy Clay Silty/Sandy Clay Silty/Sandy Clay Silty/Sandy Clay Silty/Sandy Clay Silty/Sandy Clay Silty/Sandy Clay Silty/Sandy Clay Silty/Sandy Clay Silty/Sandy Clay

Along Busia – Majanji road, the following low lying areas were identified:


55

 Km 6+800 – 7+100 : 300m  Km 14+750 – 12+000 : 250m  Km 17+250 – 17+500 : 250m  Km 21+400 – 21+700 : 300m

3.1.11 Junctions and Accesses

Intersections have been proposed as per the Design manual guidelines as well as considering the traffic flows and the design speed. The following intersections/junctions have been proposed for Musita – Lumino link. In addition, several access junctions providing access to properties adjacent to the project road have also been proposed. CHAINAGE

SIDE

JUNCTION TYPE

DESCRIPTION

Km 0+000

START

Type-C

Start of the Project road

Km 0+140

LHS

Type-B

Access to Musita

Km 2+100

CROSS

Type-A

At Lugolole

Km 13+166

R/ABOUT

Type-D

At Mayuge

Km 20+925

CROSS

Type-A

At Mpuge

Km 26+210

CROSS

Type-A

At Bunalwenyi

Km 30+490

LHS

Type-A

At Bwamula

Km 35+800

LHS

Type-A

To Buwunga

Km 36+160

RHS

Type-A

At Nankoma

Km 47+470

CROSS

Type-A

At Muterere

Km 51+540

LHS

Type-A

At Bukoli

Km 63+300

LHS

Type-A

To Bulesa

Km 63+300

RHS

Type-A

To Lugala


56

Km 66+760

RHS

Type-A

At Lunyo

Km 76+670

LHS

Type-B

To Lumino

Km 77+129

R/ABOUT

Type-D

At Lumino

Along the Busia – Majanji road intersections have been proposed at the following locations:

CHAINAGE

SIDE

JUNCTION TYPE

DESCRIPTION

Km 0+000

START

Type-D (roundabout)

At Busia

Km 19+660

RHS/LHS

Type-D (roundabout)

To Musita/Lwanda

Km 26+732

RHS

Cross junction

To Landing site

3.1.12 Footpaths, Busbays and Road Furniture 3.1.12.1 General

Segregated 2m wide footpaths/cycle paths are proposed at trading centres with high level of non-motorized traffic (NMT) and pedestrian traffic. The footpaths/cycle paths will be separated from the main carriageway and shoulders by an open Invert Block Drain (IBD). Bus bays will be provided at all trading centres, near institutions (e.g. schools, colleges, health clinics, etc) and near all major junctions. Traffic calming measures including rumble strips, bumps and appropriate warning signs will be provided where considered necessary to enhance safety. 3.1.13 Service Roads

Due to ROW constraints and safety requirements, the horizontal alignment has been designed to bypass both Musita and Lumino trading centers. In order to access these centers 6m wide access roads with 1m shoulders have been proposed as follows:  Musita – 460m  Lumino – 588m


57

In addition, service roads have also been proposed at the following trading centers to minimise conflict between local traffic and through traffic. Table below lists the locations and centres where service roads are proposed.

Location

MAYUGE NANKOMA MUTERERE BUKOLI NAMAVUNDU

Position

From Km

LHS RHS LHS RHS LHS RHS LHS RHS LHS RHS

13+300 13+300 35+200 35+200 47+250 47+250 50+800 50+800 56+800 56+800

To Km

13+900 13+900 36+000 36+000 47+800 47+800 51+400 51+400 57+500 57+500 TOTAL

Length (m)

600 600 800 800 550 550 600 600 700 700 6,500

Along the Busia – Majanji section service roads have been proposed at Busia town and Majanji trading center. 3.1.14 Climbing Lanes 3.1.14.1 Introduction

The need for Climbing Lanes has been assessed using guidelines contained in the Kenya’s Road Design Manual Part 1: Geometric Design of Rural Roads. The Manual stipulates that Climbing lanes should be introduced where longitudinal gradients are long enough and steep enough to cause significant increase in speed difference between cars and heavy vehicles. In assessment of the need for a Climbing Lane the following guidelines are considered: i.

Climbing lanes are NOT required for roads with AADT < 2000 p.c.u. in Design year 10 and in all Class D(secondary) and E(minor) roads even if AADT exceeds 2000 p.c.u. in Design Year 10.

ii. Where passing opportunities are limited on the gradients, then Climbing lanes must be considered on all A(International trunk roads),B(National trunk roads) and C(primary roads) Class roads with AADT between 2000 and 6000 p.c.u. iii. Climbing Lanes is required on roads with AADT>6000 in Design Year 10.


58

3.1.14.2 Assumptions and Application

Where Climbing lanes are required, they shall be introduced as follows: 

 

   



In Class A roads, where the speed of a typical heavy vehicle falls by 15 kph from that speed which the same vehicle would maintain in a level or downhill section of the same road. In Classes B and C roads they are applied where speed drops by 20 kph. For design purpose, it may be assumed that the highest obtainable speed on a level or downhill section of road for a typical heavy vehicle will be 80% of the Design Speed or 80 kph whichever is the lower. Climbing lane shall be terminated when the speed of a typical heavy vehicle reaches the speed at which the Climbing lane was introduced. Where Climbing Lanes are required, the widths of the traffic lanes and adjacent shoulders shall be reduced. The introduction and termination of a Climbing lane shall be effected by tapers of 60m but this not considered as part of the Climbing Lane. The start and end of Climbing lane section is calculated based on the performance of a typical heavy vehicle of power to weight ratio 90 kg/h.p. on various gradients. For the Year 10 Design traffic in p.c.u., the highest forecast traffic flow for each road section was used and converted to p.c.u. using conversion factors listed in Chapter 3 page 3.9 and considering rolling terrain of the Kenya Design Manual Part 1. i. ii. iii. iv. v.

Passenger cars – 1.0 Light Goods vehicle – 1.5 Medium Goods Vehicle – 5.0 Heavy Goods vehicle – 8.0 Buses – 4.0

3.1.14.3 Assessment of Climbing Lane Need

Lot E roads have been assessed based on Class C road as specified in the Kenya Design Manual. ROAD E1.1: MUSITA – LUMINO

 

Road Class C Year 10 Traffic = (4x34+1.5x342+5x812+8x44) = 5061 p.c.u. in Year 20 (2030)  Need for CL evaluation = Yes  Assume Design Speed = 90 km/h


59

 

Typical heavy vehicle speed on level or downhill section = 80% of 90 km/h = 72 km/h CL to be introduced when heavy vehicle speed drops to = 72 – 20 = 52 km/h

LENGTH (m)

SLOPE (%)

DISTANCE TO START OF CL (m)

MINIMUM LENGTH OF CL (m)

4+900

1100

4

400

700

Provide 900m Climbing Lane-LHS?

10+800

11+240

440

5

300

140

Not Economical

16+000

16+400

400

4

400

NA

Not required

16+900

17+400

500

4

400

100

Not Economical

21+200

21+500

300

4

400

NA

Not required

27+700

28+100

400

4

400

NA

Not required

30+000

30+360

360

5

300

60

Not Economical

30+600

30+900

300

4

400

NA

Not required

30+900

31+300

400

5

300

100

Not Economical

31+000

31+300

300

5

300

NA

Not required

31+400

32+000

600

4

400

200

Not Economical

39+500

40+000

500

5

300

200

Not Economical

40+500

41+200

700

4

400

300

Not Economical

43+300

44+500

1200

4

400

800

Provid e 1000m Climbing LaneLHS

44+700

46+000

1300

7

200

1100

Provid e 1400m Climbing LaneRHS

46+100

46+600

500

4

400

100

Not Economical

55+100

55+600

500

4

400

100

Not Economical

58+800

59+200

400

4

400

NA

Not required

76+700

77+000

300

5

300

NA

Not required

FROM

TO

(Km)

(Km)

3+800


COMMENT

60

ROAD-1.2: BUSIA – MAJ ANJI

     

Road Class C Year 10 Traffic = (4x15+1.5x360+5x134+8x11) = 1358 pcu in Year 20 (2030) Need for CL evaluation = No Assume Design Speed = 90 km/h Typical heavy vehicle speed on level or downhill section = 80% of 90 km/h = 72 km/h CL to be introduced when heavy vehicle speed drops to = (72 – 20) = 52 km/h LENGTH (m)

SLOPE (%)

DISTANCE TO START OF CL (m)

MINIMUM LENGTH OF CL (m)

10+840

240

4

400

NA

Not required

17+340

540

4

400

140

Not Economical

FROM

TO

(Km)

(Km)

10+600 16+800

3.2

Pavement Desi gn

3.2.1

Introduction

COMMENT

The project roads are intended to be upgraded to bitumen standard with 7.0m carriageway and 2.0m wide shoulders both sides. The pavement design of the project roads is based on the Ministry of Works, Housing and Communications Road Design Manual Vol. 3: Pavement Design, Part I: Flexible Pavements (July 2005). 3.2.2

Design Period

The economical analysis of the project roads is based on a 20 year analysis period. Hence a 20 year pavement design period has been adopted. It does not mean that at the end of the design period the pavement will be completely worn out, but strengthening may be required so that it continues to carry traffic satisfactorily for a further period. However, some routine


61

maintenance is expected to be performed on regular basis throughout the design period to curtail major distress propagation.

3.2.3

Pavement Design Input Data

Climate All the project roads fall in the tropical rain zone and have most rains in March to June and August to November. They are therefore in the predominantly wet regions. Traffic Loading Class The traffic loading classes for the different roads were obtained from the traffic count studies. It is found that all the project roads fall between T1 and T4 Traffic Load Classes. Traffic Loading classes are as stipulated in the design manual: Design traffic loading (E80 x 106 <0.3 0.3-0.7 0.7-1.5 1.5-3.0 3.0-6.0 6.0-10 10-17 17-30

Traffic load class T1 T2 T3 T4 T5 T6 T7 T8

3.2.3 Subgrade

The subgrade soils were tested for soaked CBR determination. These CBR values were analysed and design CBR and soil subgrade classes were obtained. Subgrade Strength Classes are as stipulated in the design manual: Design CBR %

Subgrade Strength Class

2 3-4 5-7 8-14

S1 S2 S3 S4


62

15-29 30+

3.2.4

S5 S6

Soft spots and Marshy areas

Where such sections are encountered (outside swampy sections) a selected fill material or rock fill is assumed necessary to raise the subgrade design CBR to 8%. The selected fill material shall need to be a minimum depth of 450mm , and care should be taken to ensure that there are no weak materials underlying this layer which may lead to detrimental performance. 3.2.5

Pavement Materials

Pavement materials were obtained during field investigation. It was found that plenty of lateritic gravels are available along the project roads. These gravels are suitable for stabilization with cement or lime. Field investigation also revealed the availability of rock sources along the project roads, these rocks will be suitable for crushed stone base, and bituminous pavement works. 3.2.6

Pavement Design Catalogue

The pavement design catalogue to be adopted for the design shall be as obtained from Chart W2 (Granular base/Cemented subbase) and Chart W3 (Cemented base/Cemented subase). (Road Design Manual Vol. 3: Pavement Design, Part I: Flexible Pavements). The pavement layer thicknesses given in charts shall be adjusted to provide layer thickness which is convenient during construction, and also increase thicknesses of lower layers which are cheaper than the upper layers. However care has to be taken to ensure that the proposed layers are structurally superior to those of the charts. The pavement structures presented in these charts represent alternate construction approaches differing basically in base course and surfacing materials. These are expected to render equal quality to road user perception cost. 3.2.7

Pavement Structural Design

Two options for the pavement structure have been provided. Option no. 1:


63

The pavement structure is composed of Granular Base Course on Cemented Subbase Course. The surfacing given is asphalt concrete. This pavement is much durable with minimal maintenance. However, the construction cost for the asphalt concrete is much higher compared to that of surface dressing. Option 2: The pavement structure in this option is composed of Cemented base and Cemented subbase, the surfacing is Double surface dressing. This option was not considered further during the detailed stage as the Client indicated its preference for Option 1 that uses asphalt concrete for bituminous surfacing 3.2.8

Design Traffic Loading

Traffic studies show cumulative number of standard axles as follows: Estimated traffic growth rate (pessimistic) = 8.7x10 6 Estimated traffic growth rate (realistic) = 8.99x10 6 Estimated traffic growth rate (optimistic) = 9.37x10 6 Estimated traffic growth rate (realistic) of the pavement structure Traffic class obtained is: 3.2.9

= 8.99x10 6 is adopted for the design

T6

Design Subgrade CBR

Analysis of soaked CBR test results for the road alignment subgrade soil involves establishing the design CBR for the section as obtained from 90%-ile chart. The 90%-ile value for a section is the CBR value which 10% of the test results fall below. This is obtained by plotting a graph of CBR values (arranged in ascending order) against the test number and obtain the CBR value corresponding to d = 0.1 x (n-1) where d = is the value in the horizontal axis starting from sample 1 n = number of tests used in the design.


64

DESIGN CBR (Road no.1 Musita-Lumino)

70 65 60 55 50 45 ) 40 % ( R B C

35 30 25 20 15

n = 34 tests d = 0.1 x (n-1) = 3.3

10 5 0

1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3 3 3 3

TEST

Figure 16 : Musita-Lumino Subgrade Analysis From the above figure, the design CBR = 6% DESIGN CBR FOR (Road no. 1 Busia - Majanji )

70 60 50 ) % (

40

R B C

30

n = 9 tests d = 0.1 x (n-1) = 0.8

20 10 0 1

3

5

7

9

TEST

Figure 17 : Busia-Majanji Subgrade Analysis


65

From the above figure, the design subgrade CBR = 6% 3.2.10 Design Subgrade Subgrade Class

The design subgrade class is presented in summary below.

Musita -Lumino Chainage S/No

From

1

Road Length

Design CBR (%)

Subgrade Class

(Km)


74

6

6

S3

Road Length


Design CBR (%)

To

0+000- 74+000 Busi a – Majanji Majanji Chainage

S/No

1

From

To

(Km)

2+000- 26+000

24

6

Subgrade Class

6

S3

3.2.11 Proposed Pavement Pavement Structure Structure

From design chart Chart W2 (T6, S3), the following has been adopted.

Pavement layer

Type of material

Layer thickness

SURFACING

AC(Asphalt AC(Asphalt Concrete)

50 mm

BASE COURSE

GB(Granular Base)

150 mm

SUBBASE

CSB(Cemented Subbase)

175 mm

IMPROVED SUBGRADE

G15 (Natural Gravel CBR >15%)

125 mm


66

3.3

Drainage Drain age De Desi sign gn

3.3.1

Design Return Period

The frequency of the flood for the design of drainage structures depends on the risk to be taken, that defines the degree of risk that we run in designing a structure during the anticipated service life. Therefore, the estimation of the design floods considered the ERA Drainage Design Manual, 2002 (in Road Design Manual, Vol.2 Drainage Design, 2005) which is summarized in Table 23. Table 23: 23: Design Average Recurrence Intervals for Flood/Storm (yrs) by Geometric Design Criteria (Source: ERA Drainage Design Manual, 2002 in Road Design Manual, Vol.2 Drainage Design, 2005) Structure Type

Geometric Design Standard Paved III, Gravel A

Paved III, Gravel B

Gravel C

10/5

2

2

-

10

10

5

5

-

-

-

5

25

10

5

5

50

25

10

10

50

50

25

25

100

50

50

50

100

100

100

100

200

200

100

100

Paved Ia, Paved Ib, Paved II

Gutters and Inlets* Side Ditches Ford/Low-Water Bridge Culvert, pipe ( see Note) Span < 2m Culvert, 2m < span < 6m Short Span Bridges 6m < span < 15m Medium Span Bridges 15m < span < 50m Long Span Bridges spans > 50m Check/Review Flood

Note 1: Span in the above table is the total clear-opening length of a structure. For example, the span for a double 1.2-meter diameter pipe is 2.4 meters, and the design storm frequency is therefore “culvert, 2m
3.3.2

Frequency Distribution Models

In flood frequency analysis, the objective is to estimate a flood magnitude corresponding to any required return period of occurrence. The resulting relationship between magnitude and return period is referred as the Q-T relationship. Return period, T, may be defined as the time-interval (on the average) for which a particular flood having magnitude Q T (also known as quantile) is expected to be exceeded.


67

In this work, a compatible distribution model has been considered for hydrological analysis. The comparison between the goodness of fit assessments for different distributions indicate that the Gumbel Extreme Type I distribution is more reasonable and reliable to the hydrologic events and has been widely used for estimating the design rainfall at any given return period. Therefore, the rainfall frequency analysis has been carried out using Gumbel Type I frequency distribution. A general equation equation for frequency analysis of hydrologic hydrologic events is given as (Chow, 1964). The equation for the quantile estimate is given by: R T = ∝ + K T ⌠

[Equation 1]

where RT = daily rainfall amount for return period T µ = central tendency from fitted probability distribution distribution ⌠ = standard deviation from fitted probability distribution KT = reduced variate of the probability distribution depending on return period and sample size read from probability distribution tables For Generalized Extreme Value (GEV) distribution which best fitted the data for most stations, K T can be estimated from: 



 = � − (−= ) � 



[Equation 2]

The analysis has been carried out for return period of 10, 25, 50 & 100 years as per design standard of the project. Table 24 presents the estimated design rainfall at different return period.


68

Table 24: Estimates of design rainfall at different return periods Quantile for Return Period (T), QT [mm]

Station Name

Jinja

Station Code

89330430

Statis. Distrib.

T

10000

1000

100

20

10

5

2

1.5

1.33

1.3

1.11

1.05

1.02

p

0.01

0.1

1

5

10

20

50

67

75

80

90

95

98

GEV

157.2

142.9

125.6

110.1

101.8

82.3

72.6

62.9

57.3

53.5

43.5

35.2

25.9


3.3.3

69


The term design flood refers to the flood hydrograph or peak discharge value that is finally adopted as the basis for design after giving due consideration to the flood characteristics, frequency and damage potential, including economic and other related factors. By make use of the estimated design rainfall, watershed characteristics and physical data from field visit, the design floods for the different road drainage watersheds were calculated. The adopted models are discussed hereunder. 3.3.4

Runoff Models

Despite of the model used, accurate estimation of the design discharge depends on accurate assessment of the various parameters used in the model. Among the parameters include the flow data, rainfall data, catchments area and characteristics such as mainstream length and slope, curve number, coefficient roughness, time of concentration, length of the channel and slope and catchment land use and cover. In this study, the TRRL East African Flood Model (ungauged catchment) and Frequency analysis (gauged catchment) were used.

3.3.3


The term design flood refers to the flood hydrograph or peak discharge value that is finally adopted as the basis for design after giving due consideration to the flood characteristics, frequency and damage potential, including economic and other related factors. By make use of the estimated design rainfall, watershed characteristics and physical data from field visit, the design floods for the different road drainage watersheds were calculated. The adopted models are discussed hereunder. 3.3.4

Runoff Models

Despite of the model used, accurate estimation of the design discharge depends on accurate assessment of the various parameters used in the model. Among the parameters include the flow data, rainfall data, catchments area and characteristics such as mainstream length and slope, curve number, coefficient roughness, time of concentration, length of the channel and slope and catchment land use and cover. In this study, the TRRL East African Flood Model (ungauged catchment) and Frequency analysis (gauged catchment) were used. 3.3.5

Frequency analysis

There exist different types of frequency distributions in frequency analysis models. The most applicable type of models for peak flood analysis, Log Pearson Type III distribution programmed in Excel spreadsheet was used. Table 25: Estimate of design floods at different return period Flood Frequency Calculations using log-Pearson Analysis III

(period of record 1999-2009) Return Period (years)

2 5 10 25 50 100 200

Skew Coefficient K (-0.0403)

0.0068 0.8436 1.2772 1.7369 2.0322 2.2962 2.5381


Discharge Q (m3 /s) 46 64 76 91 102 113 125

70

3.3.6

The TRRL East African Flood Model

The TRRL East African Flood Model has been recommended as the most appropriate model for the estimation of design floods for the different un-gauged catchments in East Africa and has been widely used. In the TRRL model, the base time is assumed to be the time from 1 per cent of peak flow on the rising limb to 10 per cent of peak flow on the falling limb of the hydrograph. For East African catchments, it has been found to vary between 2.7 and 11.0 unlike the US hydrographs, where the ratio of base time to time to peak is approximately 3.0. Owing to wide range, the use of a single hydrograph base on time to peak was therefore considered not appropriate. A much more stable ratio was found to be the peak flow (Q) divided by the average flow measured over the base time (Q) (Peak Flow Factor). F=

Q

[Equation 3]

Q

The peak flow was estimated if the average flow during the base time of the hydrograph can be calculated.

The total volume of runoff is given by:

RO = ( P  Y )C A * A *10 Where:

3

(m3)

[Equation 4]

P = rainfall (mm) during time period equal to the base time Y = initial retention C A = contributing are coefficient A = catchment area (km 2)

If the hydrograph base time is measured to a point on the recession curve at which the flow is one tenth of the peak flow, then the volume under the hydrograph is approximately 7 per cent less than the total runoff. The average flow (Q) is therefore given by: Q=

0.93 * RO 3600 * T B

[Equation 5]

Where: TB = hydrograph base time (hrs.)


71

Estimates of Y and C A are required to calculate RO and lag time K to calculate TB. Initial Retention (Y)

In arid and semi arid zones an initial retention of 5 mm is considered, and zero elsewhere

Contributi ng Area Coefficient (C A)

Contributing area coefficient is a coefficient that reflects the effects of the catchment wetness and the land use. A grassed catchment at field capacity is taken as a standard value of contributing area coefficient. The design value of the contributing area coefficient was estimated from the following equation. C A

= C S * C W * C L

[Equation 6]

Where: CS = the standard value of contributing area coefficient for a grassed catchment at field capacity CW = the catchment wetness factor CL = the land use factor The three factors are given in Tables 5.2, 5.3, and 5.4 of the TRRL Laboratory Report 706 (Tables 26, 27 and 28 below).

Table 26: Standard Contributing Area Coefficient (wet zone catchment, short grass cover) (Source: TRRL Laboratory Report 706) Soil Type Catchment Slope

Very Flat < 1.0 % Moderate 1-4 % Rolling 4-10 % Hilly 10-20 % Mountainous > 20 %

Well Drained

0.09 0.10 0.11 0.12


Slightly Impeded Drainage

0.15 0.38 0.45 0.50

Impeded Drainage

0.30 0.40 0.50

72

Table 27: Catchment Wetness Factor (Source: TRRL Laboratory Report 706) Catch ment Wetness Facto r

Rainfall Zone

Perenni al Streams

Ephemera Streams

1.0 1.0 0.75 0.60

1.0 1.0 0.50 0.30

Wet Zone Semi Arid Zone Dry Zones (except West. Uganda) West Uganda

Table 28: Land Use Factor (Base assumes short grass cover) (Source: TRRL Laboratory Report 706) Land Use

Land Use Factor

Largely bare soil Intense cultivation (particularly in valleys) Grass cover Dense vegetation (particularly in valleys) Ephemeral steam, sand filled valley Swamp filled valley Forest

1.50 1.50 1.00 0.50 0.50 0.33 0.33

Catch ment l ag Time (K)

The appropriate values of lag time were estimated from Table 29. Care was take in assessing which category to place a given catchment, as generally only small areas on either side of the stream are contributing to the flood hydrograph.

Table 29: Catchment Lag Time (Source: Table 5.5 of TRRL Laboratory Report 706)

Catchment Type

Lag Time (K) in hrs

Arid Very steep small catchments (slope > 20 %) Semi arid scrub (large bare soil patches) Poor pasture Good pasture Cultivated land (down to river bank) Forest, overgrown valley bottom Papyrus swamp in valley bottom

0.1 0.1 0.3 0.5 1.5 3.0 8.0 20.0


73

Base Time

The rainfall time (T P) is the time during which the rainfall intensity remains at high level. This was approximated by the time during which 60 per cent of the total rainfall occurs. Using the general intensity duration frequency equation,

i=

a

[Equation 7]

(0.33 + t d )

c

The time to give 60 per cent of the total rainfall is given by solving equation 7. 0.6 =

t d  24.33 

c



 24   td + 0.33 

[Equation 8]

Values for the various rainfall zones of East Africa are given in Table 30. Table 30: Rainfall Time (T P) for East African 10 year Storm (Source: Table 5.6: TRRL Laboratory Report 706) Zone

Index 'c'

Rainfall time (TP) (hr)

Inland zone Coastal zone Kenya Aberdare Uluguru Zone

0.96 0.76 0.85

0.75 4.0 2.0

The flood wave attenuation (T A) was estimated from equation 9.

T A =

0.028 L 1

Q

4

S

1

[Equation 9]

2

Where: L = length of main stream (km) Q = average flow during base time (m 3/s)

S = average slope along main stream The base time was estimated as: T B = T P + 2.3K + T A


[Equation 10]

74

The iterative/ trial and error solution was carried out. Initially T A was assumed zero, and two iterations were considered adequate. Knowing Q and F, the peak was calculated using equation 3. The following pages illustrate the computation process using the TRRL East African Flood Model in one of the drainage catchment. The same approach programmed in excel spreadsheet was used in the computation of the design floods in other watersheds.


a)

Catchment characteristics:

75

a)

Catchment characteristics: Catchment area, A (km 2) 8.623 km2 Land slope, S = 0.045 Main stream average Slope, Sc = 0.032 Major stream flow length, L (m) 4016 m Land use: Gently sloping catchment, cultivated down to river channel banks (sugarcane, maize, cassava) and settlement

b)

Catchment Lag time (K):

3

Arid Very steep small catchments (>20%) Semi arid scrub (bare soil patches) = Poor Pasture = Good pasture = Cultivated land (down to river banks) Forest, overgrown valley bottom Papyrus swamp in valley bottom

0.1 0.1 0.3 0.5 1.5 3 8 20

c)

STD Contributing area coefficient Cs = Soil type (Slightly impended drainage) Catchment slope (Rolling 4-10%)

0.45

d)

Antecedent Rainfall zone NYANZA UG

e)

hr

TRRL Table 4 pp 18 TRRL Fig 15: soil zones

Potential ET

5.6

mm/day

2 day antecedent 7 day antecedent Soil Moisture recharge

21.1 48.4 60.9

mm mm Mm

Catchment wetness factor , Cw Rainfall Zones

Wet zones Semi arid zone Dry zones (exept West Uganda) West Uganda

1

TRRL 706_Table 7 pp 20

TRRL Table 3 pp 17 TRRL Fig. 14

TRRL 706_ Table 3-pp17 & Table 5-pp 19

Catchment wetness factor (C w) Perennial Ephemeral strea streams ms 1 1 1 1 0.75 0.5 0.6

0.3


76

Land use factor C L Largely bare soil Intense cultivation (Particularly in valleys) Grass cover Dense vegetation (particularly in valleys) Ephemeral stream, sand filled valley Swamp filled valley Forest

1.5

g)

Contributing area coefficient, CA = (Cs*Cw*CL)

0.675

h)

Initial Retention, Y If Semi arid or West Uganda

5

f)

Rainfall time, Tp for EA 10 year storms:

0.75

mm

TRRL 706 Page 11 (summary, (h)) and Fig.14

hrs

TRRL 706_Fig 16 & Table 8

0.75 0.96

Design rainfall during time interval (T B), P (mm): 10 year daily point rainfall =

k)

Eqn 8 , TRRL

0

Inland zone Tp = Index, "n" = j)

1.5 1.5 1 0.5 0.5 0.33 0.33

5

Elsewhere, Y = i)

TRRL Table 6 pp 19

108.16

mm

1st Iteration of Base time, T B (hr): (Tp + 2.3K + T A)

7.65

hr

Assuming 1st Iteration Rainfall during base time RT B =

0

T A =

RTB = (TB/24)*(24/(T B + 0.33))^n * R10/24

100.53

mm/d

Index, n for 10 yr design storm

0.96

hr

10 yr max average daily rainfall, R10/24

108.16

mm/d

TRRL Eq 12

Where:

Area Reduction Factor, ARF = 1- 0.04*T^(-1/3) *A^(0.5) Area, A 8.62 Time, T = T B = 7.65 ARF = 0.94 Average rainfall, (P) = ARF * RT B 94.53 l)

Volume of runoff, RO (m 3) = (CA * (P - Y) * A * 1000)


521125.67

TRRL 706_Fig 16 & Table 8

km2 hr mm/d m3

TRRL Eqn 6

77

m) Average flow

Qav =

=17.60 m3/sec

(0.93*RO/(3600*T B)

TB (2nd approximation iterative procedure) ITERATION OF Qav and T B Qav TB 17.5979 7.65 17.5959 7.6509 17.5959 7.6509

T A 0 0.0009 0.0009

New values after Iteration: 10 year daily point rainfall R10/24 = Rainfall during base time, RT B = (TB/24)*(24/(T B + 0.33))^n * R10/24 Area Reduction Factor, ARF = 1- 0.04*T^(-1/3) *A^(0.5) Area, A Time, T = T B = ARF = Average rainfall, (P) = ARF * RT B n)

Volume of runoff, RO (m 3) =

Therefore

Design Peak flow for T= 25, 50, 100 years Peak Discharge Factor

mm

17.60

m3/sec

40.47 2.3

m3/sec

K= F= F=

3

hr

Q 10 =

40.47

Q100:Q2

2.075

Q50:Q2

1.825

Q25:Q2 Q10:Q2 Q100:Q10 Q50:Q10 Q25:Q10

1.667 1.490 1.393 1.225 1.119


km 2 hr

521131.95 m 3

(CA * (P - Y) * A * 1000)

DESIGN PEAK FLOW, Q = (F* Qav) Where peak flood factor, F is given as: Computed For K < 0.5 hr, For K > 1.0 hr,

108.16 mm/d = 100.53 mm/d

8.62 7.65 0.94 94.53

Average flow, Qav = o)

TRRL Eq 13

TRRL Eqn 6

TRRL Eqn 5

2.8 2.3 m 3/sec

TRRL Laboratory Report 623 Appendix 1, Fig. 3

Q100 Q50 Q25

56.36 49.56 45.27

m 3/s m 3/s m 3/s

78

3.1.8

Design Discharges

Tables 31 and 32 present the design discharges of the project road under the project for the different return periods.

Table 31: Summary of design floods for different return period Road E1.1- Musita-Lumino Catch. Ref.

283 284 286 287 289 290 292 293 294 295 296 297 298 299 300

301 302

Chainage from Musita 5+060 5+440 7+276 11+250 11+660 15+870 16+833 18+800 19+700 21+100 24+000 25+810 28+640 29+465 30+910 31+970 34+360

303-306

37+960 40+240

307 308 309 310 311 312 313 314

45+990 50+260 54+130 54+870 58+590 63+270 73+330 76+660

Northing

546926 547329 548534 551778 554420 556063 558983 559865 561223 562439 564029 565785 568503 569306 570662 571704 574025 574151 577490 579850 582090 582238 585222 588250 591146 591696 594212 597842 607154 610229

Easting

55901 55567 54543 51971 50807 50594 50334 50573 50599 50433 50880 50809 50122 50281 50663 50447 50099 50076 50202 50501 50406 50370 49136 46187 41090 43504 40880 38019 35225 36199


Design flood discharge (m3 /s)

Catch. area 2 (km ) 1.34 1.18 8.62 0.74 1.24 4.78 1.54 0.42 0.21 0.40 2.03 0.29 0.73 1.18 0.71 0.44 14.32

10-yr 6.28 5.56 40.47 3.66 3.83 14.72 7.86 1.28 0.64 1.24 6.26 0.88 2.24 5.53 2.17 1.29 44.12

25-yr 7.02 6.22 45.27 4.09 4.28 16.46 8.79 1.44 0.72 1.39 7.00 0.99 2.50 6.18 2.43 1.46 49.35

50-yr 7.69 6.80 49.56 4.48 4.69 18.02 9.62 1.57 0.78 1.52 7.66 1.08 2.74 6.77 2.66 1.59 54.03

100-yr 8.75 7.74 56.36 5.09 5.33 20.50 10.94 1.79 0.89 1.73 8.72 1.23 3.11 7.69 3.03 1.99 61.44

3.75 24.97

11.56 88.43

12.93 98.91

14.16 108.29

16.10 123.15

9.09 11.47 13.18 10.54 12.42 1.13 3.26 0.97

42.58 49.98 42.82 32.48 30.38 7.01 17.82 3.00

47.63 55.9 47.89 36.33 33.98 7.84 19.93 3.36

52.14 61.2 52.43 39.77 37.2 8.59 21.82 3.67

59.3 69.6 59.63 45.23 42.31 9.76 24.81 4.18

79

Table 32: Summary of design floods for different return period Road E1.2- Busia-Majanji Catch. Ref.

325 324 323 322 321 320 318 317 316 315

Chainage from Busia 1+125 1+480 6+970 10+310 10+885 11+860 16+310 17+390 21+600 23+180 25+500

Northing

Easting

620283 619949 616014 614350 614081 613606 611423 610871 610325 610300 610374

51064 50892 47143 44331 43819 42931 38133 36614 34182 32610 30420

Catch. area 2 (km )

Design flood discharge (m3 /s)

0.19 0.57 2.0 0.88 0.16 8.35 3.96

10-yr 0.88 2.87 10.03 4.41 0.81 24.68 17.82

25-yr 0.98 3.21 11.22 4.94 0.90 27.61 19.94

50-yr 1.07 3.51 12.29 5.4 0.99 30.22 21.83

100-yr 1.22 3.99 13.97 6.14 1.12 34.37 24.82

4.96 0.80 1.38

22.18 3.12 5.36

24.81 3.49 5.99

27.16 3.82 6.56

30.89 3.12 7.46

3.4 Structure Selection 3.4.1 Desig n Philos oph y Provision of efficient and adequate drainage system is extremely important for the life of the road in terms of reducing maintenance cost and preventing adverse environmental impacts. Inadequate drainage design will contribute highly to the deterioration of the pavement structure. Areas to which attention should be given could be categorized as surface and subsurface drainage along the road and cross drainage. The design of side ditches, culvert capacities and bridge waterway openings are governed by the criteria specified in the UNRA manual. The surface drainage system, which will take care of rain water from the pavement surface, adjacent cut slopes and the ground cross fall will be treated by proper cambering of the roadway and by the introduction of side ditches. Minor drainage structures are specified as standard structures and are recommended based on hydraulic efficiency, terrain condition, type of foundation material, the safety of the surrounding dwellers and road traffickers. Except for the bridges, standard drawings are adopted unless there is a call for site specific design. The type and size of drainage structure specified for a particular location is often determined based on site specific conditions. But a generalized structures


80

selection effort is made to initially identify the benefits of a certain types of structure based on the general prevailing local condition, like availability of local material at the project vicinity, skilled labour, capacity of the construction industry and cost efficiency. Bridge is recommended where it is more economical than a culvert, perhaps due to the need to bury a culvert under a high level of fill. They are also employed to satisfy land use requirements, to mitigate possible environmental harm with a culvert, to avoid floodway or irrigation canal encroachments, and to accommodate large debris. Culverts are used where bridges are not hydraulically required, where debris is tolerable, and where they are more economical than a bridge. Culverts can be concrete box culverts, concrete slab, reinforced concrete pipe culverts, or corrugated metal culverts or plastic. Concrete box/slab culverts are constructed with a square or rectangular opening, and with wing walls at both ends. They are usually specified for larger flows, where the area of the opening is larger than a practical pre-cast circular concrete pipes. There may also be the case where the cost estimate of concrete box/slab culverts constructed on site are less expensive than manufactured and/or imported pipe culverts.

3.4.2 Bridges The choice of a bridge type is a matter of 

Safety



Environmental factors



Economics

 Availability of local construction materials in enough quantity and quality  Availability of semi skilled and skilled labour in enough number to be deployed for the project work 

The current capacity of the construction industry



The possibility and ease of construction



The possibility, ease and frequency of regular maintenance

3.4.2.1 Bridge Material

The following table highlights the comparison of various bridge construction materials that the consultant has taken into account in reaching a decision on the


81

Reinfor ced Concrete Availability of material

Composite /steel& concr ete/

 Sand /available at the project route/


 Aggregate /can be crashed from

 Aggregate /can be crashed from

quarry within the project site/

Steel  Steel profiles all /imported/

quarry within the project site/

 Cement /locally produced at Tororo/


 Reinforcement bars/ imported/

 Reinforcement bars/ imported/  Steel profiles/imported/

 Low cost Advantage

 Structural advantage to reduce dead

 Flexibility in design

 Fast to assemble  No

load

shuttering

and

false

 Common practice

 False work not required

 Heavy self weight

 Relatively higher cost

 Higher cost

 Needs regular maintenance effort

 Needs regular maintenance

Disadvantage  Takes quite some time to build  Requires false work to be erected in

work

effort  Some times required special

the river course unless precast used

welding task First

Priority & reason

second

third

 can easily be done by the available skilled labor in the market  Concrete inputs are very easily available within the project route which can result in higher cost reduction  Labour

intensive

hence

creates

money temporary jobs

Abu tm ent/Win g wall s Reinfor ced Concrete Availability of material

Masonry


 Stone /available at the project route/

 Aggregate /can be crashed from quarry within the project


site/


 Cement /locally produced at Tororo/  Reinforcement bars/ imported/


82

Advantages

 Freedom of having taller heights

 Lower cost

 Reduced self weight

 economical for height less than 10m

 Good to distribute load to weak foundation material

 masonry work is a common practice can be done

 No risk of quality, concrete is mixed at batching plants.

easily  do not require shuttering work

 Relative higher cost Disadvantage

Priority

&

 Supervision difficulty in controlling the quality of

 Requires shuttering & scaffolding work

mortar used

First

Second

 Better quality, long live despite the relative higher cost

 Relative lower costs due to quality masonry

reason

stone is available within the project route

selection of the type of material for the construction of all bridges in the project. Incorporating the general factors for the choice of a bridge type above and taking into consideration the following points: 1. evaluating the result of existing structures assessment 2. results of the detail geotechnical foundation investigation 3. discussions and approval made by the client /UNRA/ reinforced concrete for both super structure and abutments/wing walls is selected for all new bridges of the entire project roads. 3.4.2.3 Bridge Structural System

Though the selection of the bridge system is mostly site specific, simply supported structural bridge system with 12 meter length and its multiple, is selected as a standard bridge for the entire project roads. The following important points were considered in selecting the bridge system. 1. Standardizing is the TOR requirement 2. Standardizing minimizes cost by allowing repeated us of forms, reduced effort in bar bending and easy to master the details for the construction task force 3. Discussions made with UNRA bridge team


83

3.4.2.5 Bridge Construction System

In view of the topographic formation of the project routes and river crossings, the design consultant opts to adopt precast superstructure standard system of construction for all the new bridges for the entire project roads. The following important additional points are also taken into consideration in selecting the standard precast system. 1. The existence of new bridges in swamps crossings, demands fast way of construction to finalize the construction of the bridges during the dry period where the water flow is low 2. Risk of settlement and difficulty in using props to support formworks on the soft bed material unless replaced. 3. The availability of hauling and lifting equipments, capacity of the construction industry is assessed, discussed and agreed with UNRA bridge team.

3.4.3 Slab/Box Culverts As defined earlier, slab culverts are those with top slab resting on gravity type abutments (usually masonry) each done separately, and box culverts are those having monolithic top slab, bottom slab and the vertical walls. Slab culverts are usually recommended in road sections having good foundation or bed material with minimum risk of settlement and scouring at abutment foundation. Box culverts are proposed on areas where the foundation material is found weak and to avoid any possibility of foundation failure. After putting in to consideration the following points: 

 

Considerable number culverts are required in areas where the project roads intercept the swamps and their detail geothechnical investigation revealed that the foundation material at shallow depth is weak. Having difficulty to control the quality of mortar to be used in the formation of masonry abutments in case of slab culverts The better quality and rigidity of the box culverts is demanded and approved by the client.

Box culverts are selected for the entire project roads.


84

To allow a repeated use of formwork and minimize cost and time, standard span box sizes are adopted for the entire project roads. Their detailing is shown on the standard box culverts in the book of drawings.

3.4.4 Pipe Culverts The minimum size of pipe culvert proprosed to be used as cross-drainage on entire project roads is 900mm in conformity with the UNRA drainage design manual. Because of economy, easy of production at site and durability standard concrete pipe is selected to be used for the entire project roads. Their detail is shown in the standard pipe culverts drawings Concrete headwall is selected to be used for the pipe culverts in the entire road project roads despite its relative higher cost after considering the following facts.  

Better quality at relative higher cost than brick or masonry Demanded and agreed by the client/UNRA/

The concrete head wall is designed in three different models to suite the smooth inflow of water into the pipes. The selection is made site specific to avoid potential scour at the inlet and outlet. Their detail is shown on the standard pipe culverts in the book of drawings. The table below highlights the comparison made between the various material alternatives proposed for pipe culverts.

85


Pipe options Concrete

Plastic

Head wall opti ons Arm co

Masonry

Brick

Concrete

Pipe options Concrete  Sand /available at the project route/

Material Availability

Head wall opti ons

Plastic Imported

Arm co Imported

 Aggregate /can be crashed from quarry within the project site/  Cement /locally produced at Tororo/  Reinforcement bars/ imported/  Low cost

Advantage

 Can be produced at site  durable

Masonry  Stone /available at the project route/  Sand /available at the project route/  Cement /locally produced at Tororo/

 easy handling

 easy handling

and transport

and transport

Brick  Brick /everywhere available at the project route/  Sand /available at the project route/  Cement /locally produced at Tororo/

 low cost

 moderate cost

 manageable to build several culverts along the route

 manageable to build several culverts along the route

Concrete  Sand /available at the project route/  Aggregate /can be crashed from quarry within the project site/  Cement /locally produced at Tororo/  Reinforcement bars/ imported/  better quality  extended life  easy to control material quality

Disadvantage

 handling

 higher cost  could be attacked by chemicals

First

priority & reason

Second

 higher cost  could be attacked by chemicals  possibility of corrosion  mostly stolen Third

 lower cost due to availability of local materials within the project vicinity

 difficult to control quality of mortar

 requires plastering

 relative higher cost

 lower durability

 reqiures shattering

 difficult to control quality of mortar First

Second

Third

 relative lower cost

 higher durability  avoids at large hard currency requirement


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3.4.5 Paved Side Ditches Grouted stone pitching side ditches/ road gutters/, if well done and maintained regularly, can serve the purpose they are intended for as the design consultant looked around at the existing roads and on the main trunk roads. Grouted stone pitching trapezoidal open channel side ditches are selected as standard paved side ditches for road gradient exceeding 3% in the entire project roads outside of town or trading centres. Very low relative cost as compared to a precast or cast-insitu concrete paved ditch is the prime factor for the selection of grouted stone pitching side ditches as standard. However, paved side ditches in towns and trading centres need to be covered to allow access for pedestrians and traffic at selected locations. To secure safe and long lasting covered paved ditches the design consultant selected rectangular reinforced concrete paved side ditches with cover at selected positions as standard for all the towns and trading centres in the entire project roads. The selection was also discussed and agreed with client’s engineer team. Please refer to book of drawings for the Standard Paved Side Ditches and Standard Paved Side Ditches for Urban and Trading Centres for details.

3.5

Hydraulic Desig n

3.4.5 Paved Side Ditches Grouted stone pitching side ditches/ road gutters/, if well done and maintained regularly, can serve the purpose they are intended for as the design consultant looked around at the existing roads and on the main trunk roads. Grouted stone pitching trapezoidal open channel side ditches are selected as standard paved side ditches for road gradient exceeding 3% in the entire project roads outside of town or trading centres. Very low relative cost as compared to a precast or cast-insitu concrete paved ditch is the prime factor for the selection of grouted stone pitching side ditches as standard. However, paved side ditches in towns and trading centres need to be covered to allow access for pedestrians and traffic at selected locations. To secure safe and long lasting covered paved ditches the design consultant selected rectangular reinforced concrete paved side ditches with cover at selected positions as standard for all the towns and trading centres in the entire project roads. The selection was also discussed and agreed with client’s engineer team. Please refer to book of drawings for the Standard Paved Side Ditches and Standard Paved Side Ditches for Urban and Trading Centres for details.

3.5

Hydraulic Desig n

3.5.1 Minor Drainage Struct ures 3.5.1.1 Paved Side Ditches

The size of side drains is determined from the Manning’s open channel equation, Q=

(1/n)*A*(R2/3)*S1/2

Q= A= R= s= n=

discharge in m3/s area of flow in m2 hydraulic radius bed slope roughness coefficient

Where,

And the depth of flow is kept 0.4m according to UNRA Drainage Manual to protect possible saturation and erosion of road pavement. The channels from the road surface are estimated using the rational formula: Q=0.278*C*I*A Where, Q= C= I= A=

Discharge in m3/s Run – off coefficient Intensity of rainfall in mm/hr for 10min storm with ten years return period Area contributing to channel flow in Km 2

Flow from connecting channels to these side drains is determined according to the specific situation.


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3.5.1.2 Pipe Culverts

The hydraulic capacity of existing pipe culverts has been obtained from the tables in the UNRA Drainage Manual against their opening sizes, bed roughness of 0.015 and bed slop of 1% and allowing only 50% efficiency; please find these tables in Appendix 9.19 of the same manual. The discharge capacity of each and every pipe is compared with calculated channel design discharge with 25 years recurrent period. We found that in most of the cases the existing pipe culverts have inadequate hydraulic capacity to accommodate the anticipated design discharge. A table incorporating the opening sizes, type and hydraulic capacity of existing pipe culverts, the corresponding design discharge, the new structure opening size and its hydraulic capacity is prepared for detail clarification and presentation. Except for the relief and local pipes all the new pipe culverts are checked against head water depth ratio (Hw/D) greater than 1.2 to avoid scour damage to the inlet side of the road embankment and also to avoid excessive flooding upstream allowing 250mm free board below the road final level on the same table using HY8 computer software. Please refer to the table in Appendix-6.

3.5.2 Major Drainage Structures 3.5.2.1 Box Culverts

Where the design discharge is found over the capacity of the maxmum size of double pipe culverts, the box culvert is selected. The preliminary size of all box culverts is verified using HY-8 computer software after having the final road levels and bed slop. Both inlet and outlet control flows shall be checked by applying the final invert level and available upstream flow head after allowing 250mm free board below the road final level. Based on the result obtained from the computer program and soil particle size of the flow bed channel, bed protection work shall be recommended to avoid or minimize bed erosion. Please refer Appendix 6. The project box culverts schedule showing the following details of each and every box is prepare:

     

the invert level, culverts slope flow direction skew angle if any culverts length and head wall quantities additional protection work if there is any

| FINAL Detailed Design Report_Rev.1-AUG 2012 |

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3.5.2.2 Bridges

Bridges are selected in defined river flows where there are existing bridges, the design flow couldn’t be accommodated by box culverts and at least to maintain the opening size of the existing bridge and told by the local community repeated over flooding even though not supported by the hydrology analysis. And in swamps where, the design discharge is over the capacity of box culverts in series, to allow passage of expected debris and to assure free movement of the aquatic life, bridges are also recommended. The capacity of the existing bridges and the preliminary opening size of the new bridge required to accommodate the design discharge for each particular bridge location is determined from the Manning’s Equation for open channel flow and allowing free board of 1.5m according to UNRA Manual. Q=

(1/n) .A. R2/3 . S1/2

However, the preliminary bridge opening size is verified using WSPRO or HEC-2 software to insure the provided opening is safe against upstream flooding and excessive flow velocity. Please refer to the bridge hydraulic calculations and results in Appendix-4. Scour at bridge location is very important for the safety of bridge. We studied the local scour problems at those bridges where the bed material is other than rock bed. The local scour at pier is a function of bed material size, flow characteristics, fluid properties and the geometry of the pier. The scour depth at pier as given by the CSU (Colorado State University) equation is; 0.65

 a Ys = 2Y1K 1K 2 K 3    Y1 

Fr

0.43

Where; Ys = scour depth Y1 = flow depth directly upstream of the pier, [ft] K1 = Correction factor for pier nose shape K2 = Correction factor for angle of attack of flow K3 = Correction factor for bed condition a = Pier width, [ft] V1 = mean velocity of flow directly upstream of the pier, [ft/sec] 1/2 Fr 1 = Froude number = V1/ (gy1) For the constants and detail of the formula please refer to UNRA’s drainage manual section 10.8.3.

Where the demand for scouring protection, river training and bank protection work exists their design is explained on the same sheet of the bridge hydraulic design.


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3.6

Struct ural Design

3.6.1 Minor Drainage Struct ures 3.6.1.1

Paved Side Ditches

Paved side ditches are constructed as v-shaped channel following the natural stable soil slope except at towns and trading centres where rectangular channels used. The rectangular channels are designed to resist lateral earth pressure and traffic live loading at places where covering slab required. The concrete covers are also designed to withstand the traffic live loading safely. Please refer to Appendix 6-Structural Design Calculations. 3.6.1.2

Pipe Culverts

Structural design of concrete pipes usually done at standard level so that they can withstand the design live loading and the surrounding soil pressure safely. And these designs are confirmed by laboratory testing according to standard specification. Standard concrete pipes sizes, detailed and specified according to AASHTO standard specification M-170 or M-242 are adopted for this project. Basically a minimum soil cover of 600mm is adopted to reduce the effect of concentrated live load unless otherwise an additional slab is put on the top of the pipe. Class-C bedding is adopted for all concrete culvert pipes bedding for the entire project unless otherwise Class-A or Class-B bedding is approved by the engineer according to specific need.

3.6.2 Major Drainage Structures 3.6.2.1 Box Culverts

Box culvert structures are designed as rigid frame structural system. The following loadings are considered in the design. 1. 2. 3. 4.

Earth pressure from surrounding backfill material Weight of soil above Design live loading Weight of water if exists.

Design calculation is carried out for all box culverts which are selected as standard for the project all according to UNRA Manual and BS5400 Standard. SAP 2000 software is used for the structural frame analysis. Please refer to Appendix 6Structural Design Calculations. 3.6.2.2 Bridges

List of New Bridges No new bridges are required on Musita-Lumino/Busia-Majnaji roads. | FINAL Detailed Design Report_Rev.1-AUG 2012 |

90

Material Quality a) Concrete Quality

Concrete quality of Grade 30 (with characteristic strength 30MPa of 150mm cube at 28 days according to BS 5400 section 5.1.4 table-5) is adopted for all the bridge super and substructures in the entire project. b) Reinfor cement Quality

Reinforcement steel quality of Grade 460 (with minimum characteristic strength of 460MPa according to BS Cl 5.1.4 table-6) is adopted for all the bridge super and substructures in the entire project. Design Method The bridge reinforced concrete members are design to the ultimate limit state design and checked for crack width control and servicibility limit state all according BS5400 Part-4 for concrete structures. Bridge Loading All the structural design loadings of the new bridges are considered according to UNRA Bridge Design Manual together with BS5400 Part-2 for loading. a) Live Loadin g

The bridge structure and its elements are designed to resist the more severe effects of either: Design HA loading (see UNRA 6.4.1) or Design HA loading combined with design HB loading (see UNRA 6.4.2). Where, b) HA loadings HA loadings are a formula loading representing normal traffic. It consists of a uniformly distributed load/ UDL/ and knife edge load / KEL /combined, or of a single

wheel load, including 25% impact. The UDL shall be taken as 30kN per linear meter of notional lane for loaded lengths up to 30m, and for loaded lengths in excess of 30m it shall be derived from the equation.

( )

W = 151 1 L

0.475

but not less than 9

Where, L is the loaded length (in m) and W is the load per meter of lane (in KN) The KEL per notional lane shall be taken as 120kN.

c) Single Nominal Wheel

One 100kN wheel placed on the carriageway and uniformly distributed over a circular contact area assuming an effective pressure of 1.1N/mm 2 (i.e 340 mm | FINAL Detailed Design Report_Rev.1-AUG 2012 |

91

diameters) shall be considered. Alternatively, a square contact area may be assumed, using the same effective pressure (i.e. 300mm side). d) HB loadings

Those derived from the nature of exceptional industrial loads (e.g. electrical transformers, generators, pressure vessels, machine presses, etc.) One unit shall be taken as equal to 10 KN per axle (i.e. 2.5 KN per wheel). The overall length of the H B vehicle shall be taken as 10, 15, 20, 25 or 30 m for inner axle spacing of 6, 11, 16, 21 or 26 m respectively, and the effects of the most severe of these cases shall be adopted. The overall width shall be taken as 3.5 m. The minimum number of units to be used shall be 25 units for all public highway bridges. After having discussion and approval by UNRA 37.5 units of HB loading are used for the design all the bridges in the entire project.

Fig 16: Dimensions of HB vehicles e) Longit udinal Loading

The longitudinal load resulting from traction or braking of vehicles and shall be taken the more severe of 1) The nominal load for HA shall be 8 kN/m of loaded length plus 200 kN, subject to a maximum of 700 kN, applied to an area one notional lane wide x the loaded length or 2) The nominal load for HB shall be 25 % of the total nominal HB load adopted, applied as equally distributed between the eight wheels of two axles of the vehicle, 1.8 m apart and applied at the road surface in one notional lane only . f)

Accidental Load Due to Skidding

A single nominal point load of 250KN is considered in one notional lane only, acting in any direction parallel to the surface of the highway .


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g) Wind Load

All the project bridges are categorized into terrain category 1 with velocity pressure of 0.81KN/m2 structure height of 5m. However, wind load is not considered in our design since all the bridges in the entire project are small at low level and wind loading doesn’t govern. h) Live Load Surcharge

Live load surcharge for properly consolidated backfill material: (a) (b) (c) i)

for HA loading : 10kN/m 2; for HB loading 37.5 units : 16.25kN/m 2

Earthq uake Loading

The project bridges are located in Zone 2 with acceleration coefficient (A) = 0.07 and iImportant classification(IC) of class I. Seismic performance category (SPC) = 2 and soil profile type II with site coefficient(S) = 1.2. Detailed seismic analysis is not required for a single span bridge or for bridges classified as SPC 1 & 2 (Cl.9.4.2 UNRA). But the connection of the superstructure to the substructure shall be designed to resist a horizontal seismic force equal to 0.20 times the dead load reaction force in the restrained directions . Bearing seats supporting the expansion ends of girders shall be designed to provide a minimum support length N (in mm) measured normal to the face of an abutment or pier, not less than that specified below: N = 203 + 1.67L + 6.66H (mm) where L = length, in meters of the bridge deck to the adjacent expansion joint, or to the end of the bridge deck. H = average height, in meters of columns supporting the bridge deck to the next expansion joint for abutments H = column or pier height in meters for columns and/or piers

3.6.2.3 Substr uct ure

Reinforced concrete type substructures designed to safely transfer all loads from the superstructure to the underlying soil strata within its bearing capacity without excessive setlement. a) Pier

Twin wall type reinforced concrete pier with common footing pad and independent hammer head beam seat is designed to safely transfer superstructure loads to the foundation material for all the bridges in the entire. In the design all fractional values are taken to the full numbers which allow us to have a few sizes for construction simplicity and economy. Simi-circular shape edge is provided for a better hydraulic performance and durability. | FINAL Detailed Design Report_Rev.1-AUG 2012 |

93

The following loads are considered in the design processes. 1. 2. 3. 4.

Earthquake forces from the superstructure and the pier itself Longitudinal forces from the superstructure Self weight and dead load from superstructure Live load reaction

Please refer to Appendix 6-Structural Design Calculations. Figure 17 : Longitudinal Elevation

b) Abutment

Cantilever reinforced concrete abutment with 45 degrees flared wing walls is designed to safely transfer all loads from the superstructure and the back fill soil to the foundation material. The following loads are considered in the design processes of abutments: 1. 2. 3. 4. 5.

Self weight and dead load reaction from superstructure Live load reaction from superstructure Traffic surcharge load Lateral earth pressure Longitudinal forces from the superstructure

Please refer to Appendix 6-Structural Design Calculations. Figure 18 : Elevation


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3.6.2.4 Superst ruc tur e

Voided slab type superstructure is used for the standard bridge superstructure for the entire project. The voided slab is split into mid and end pre-cast units to facilitate the pre-cast production and having reduced lifting weight. Figure 19 : Precast Units

Raised walkway with removable cover utility channel is provided on bothsides of the carriage way. Figure 20 : Precast Units

The lifting weight of the end unit is around 10 tons and 11 tons for the mid unit. Carriage way width of 7.5meters with sidewalks way of 2.0meters width each side is agreed with UNRA bridge engineers and provided for all the bridges in the entire project. The total bridge width is therefore 11.5 meters. Accordingly two end units and eight units of mid units are put side by side to formulate the total bridge width.


95

Figure 21 : Bridge Cross-section

The pre-cast voided slab units are modeled and designed as single beam each shearing the live load as the same way it is assumed distributed in sold slab. It is assumed that the 10cm thick cast-insitu slab will fully helps in distributing the wheel loads. Please refer to Appendix 6-Structural Design Calculations.

3.6.2.5 Bearings

No special type of bearing except PTFE/similar pads at each precast voided slab beam at one of the two ends is provided to insure horizontal load transfer at one end only. At the other end fixity can be achieved using steel dowels or any other suitable system which be worked with the precast units. 3.6.2.6 Expansio n Jo int s

No expansion joint detail is required for short span bridges like 12m span bridges. 3.6.2.7 Railings

Prefabricated steel tube sections which can be assembled at site and bolted to the precast end unit are selected for the bridge railing. This can help to facilitate the early completion of the bridge work. The steel railing is simple looking and can easily be maintained after traffic damage. All the railing components are designed to resist the specified design load according to the manual. Please refer to Appendix 6-Structural Design Calculations. 3.6.2.8 Deck Drainage

Deck drainages at every end quarter point of the span on both sides are provided. 200mm by 75mm rectangular galvanized steel hollow section is selected to allow enough opening without clogging by silt for the perfect flow of water which is a common major problem at most bridge sites.


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3.7

Quanti ty and Cost Estimation

3.7.1

Determination of Quantities

Determination of the quantities for the various aspects of the design has been made for each of the five project roads. Civil 3D road design programme has been used to produce the various road component quantities up to wearing course level. The cross-section costed is that detailed in the Book of Drawings, incorporating a 7.0 m wide carriageway with 1.5 m shoulders. For all other items, quantities have been calculated based on preliminary design requirements as determined from the site investigations.

3.7.2

Unit Rates

Considering the nature and extent of the Works to be undertaken for this project, it is deemed that only highly experienced and well-equipped contractors could successfully undertake and complete the works in a competent and satisfactory manner. All costing, therefore, are based on this assumption. The unit rates are based on the presumption of a non-restricted tender in which contractors from countries with low foreign personnel costs and overheads, who are - or have been - active in Uganda or elsewhere in the region, can be expected to submit very competitive bids, with rates appreciably below conventionally derived unit rates. For the major construction items the unit rates have been derived from first principles and compared with the rates in force on an ongoing project of a similar nature being undertaken by the Client. The breakdown of unit rates was presented in a separate volume during the Preliminary Design stage and remains unchanged.

3.7.3

Provisions

Preliminary and General Items have been estimated at 10% of the Works Items, whilst Dayworks have been estimated at 2% of the Works Items. A 10% allowance has been made for physical contingencies and a 5% allowance for financial contingencies during the period of construction. The estimate is in Uganda Shillings and no separate provision is made for escalation between the present and commencement of construction. The cost of design has been omitted, whilst a 5% provision has been made for construction supervision. The estimated costs for land take, environmental mitigation and removal and relocation of services have also been taken into account.


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Final Detailed Design Report - Musita _ Majanji Road

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