Create Subassemblies That Think Outside the Box With Subassembly Composer for AutoCAD® Civil 3D®

Create Subassemblies That Think Outside the Box With Subassembly ® ® Composer for AutoCAD Civil 3D Kati L. Mercier, P.E. – P.E. –Nathan Nathan L. Jacobson & Associates, Inc.

CI4252

Intended for existing AutoCAD Civil 3D users, this class explores the potential of Subassembly Composer for AutoCAD Civil 3D 2011 and 2012, available in the Subscription Center. Subassembly Composer provides users with an easy-to-use interface to visually create complex subassemblies without the need for advanced programming knowledge. With forethought and ingenuity, users can create custom subassemblies to meet their specific needs that can be used again and again once they are imported into Civil 3D. Learn what it takes with these in-depth, step-by-step instructions that will give you the skills to go back to the office and wow your coworkers with your own custom subassemblies specific to your standards. With the subassemblies already available in the Civil 3D tool palette and the subassemblies you create with the tool box in the Subassembly Composer, your corridors will have endless possibilities. Attendees should be familiar with the subassemblies available in Civil 3D and how to utilize them in assembly and corridor creation.

Learning Objectives At the end of this this class, you will will be able to: 







Define appropriate input and target parameters that allow for end user customization once they are imported into Civil 3D Create a complex flowchart built with subassembly subassembly logic tools available in the tool box Identify Visual Basic expressions and other settings that are available for use when creating subassembly geometry or constructing conditionals Evaluate a flowchart and preview a subassembly to confirm that all scenarios have been analyzed

About the Speaker Speaker Kati Mercier, earned her B.S. in civil engineering from Virginia Virginia Tech in 2004 . Since then she has worked as a project engineer at Nathan L. Jacobson & Associates, Inc., a consulting civil and environmental engineering firm in Chester, Connecticut. The firm specializes in providing engineering consultation, review, and design to local municipalities and private clients. Kati has earned her Professional Engineering license in the states of Connecticut and New York. Recently she has played a significant role in transitioning the firm from Land Desktop to Civil 3D. Kati is an AutoCAD Civil 3D 2011 Certified Professional and a contributor to the civil4d.com blog. She is also an active participant in the Autodesk Subassembly Composer for AutoCAD Civil 3D 2011 discussion group. [email protected] www.twitter.com/KDinCTPE

Create Subassemblies That Think Outside the Box With Subassembly Composer for AutoCAD® Civil 3D®

Autodesk Subassembly Composer for AutoCAD Civil 3D The „Subassembly Composer® for AutoCAD Civil 3D® ‟ (hereafter referred to as Subassembly Composer) program is used to create subassemblies to supplement the stock subassemblies that come with Civil 3D. Before composing any subassembly, one of the first documents you should examine is the “AutoCAD Civil 3D Subassembly Reference document” (scan QR code at right or go to http://images.autodesk.com/adsk/files/c3dstocksubassemblyhelp.pdf ). If you can‟t find a stock subassembly that will solve your problem, this document will be a beneficial aid in using terminology and naming conventions that are already standard to Civil 3D users. You may think that when you make your own subassembly that these conventions are not important. But you may wish to share the assembly with coworkers and colleagues in the future, or you may return to it after a while and it will be easier to understand if you use already established naming conventions. The Subassembly Composer consists of five individual window panels: the [Tool Box], the [Flowchart], the [Preview], the [Properties], and the [Settings and Parameters]. Each of these window panels may be moved around independently using the docking controls (icon shown at right) to serve the user‟s needs. At any time the default position can be regained by going to the View menu and selecting “Restore Default Layout.”

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The [Tool Box] The [Tool Box] is the storage location for elements available for constructing the subassembly. This panel will provide all of the elements used to build your flowchart. There are five sections: Geometry, Advanced Geometry, Auxiliary, Workflow, and Miscellaneous. To use any of these elements you simply click on the desired element and drag and drop it over into the [Flowchart]. The [Flowchart] The [Flowchart] is workspace used to build and organize the subassembly logic and elements. A flowchart could be a simple straight line of logic or it can be a complex tree of branching branching decisions either way always beginning at the Start element. If there is a problem with your subassembly a small red circle with an exclamation point will be displayed in the upper right hand corner of this panel. The [Preview] The [Preview] allows you to view your current geometry. There are two preview modes: 



Roadway Mode which shows the subassembly built using any target surfaces, target elevations, and/or target offsets; and Layout Mode which shows the subassembly built using only the inp ut parameters (no targets).

At the bottom of this panel are two checkboxes for Codes which are shown in brackets [] and Comments which are shown in parentheses (). If any Codes or Comments were entered in the properties for the points, links, or shapes then this information will be listed next to the applicable geometry. The [Properties] The [Properties] is the input location of the parameters that define each geometry element. The [Settings and Parameters] The [Settings and Parameters] consists of five tabs that define the subassembly: Packet Settings, Input/Output Parameters, Target Parameters, Superelevation, and Event Viewer.

The Typical Workflow The typical workflow for creating a subassembly is broken into six steps. This is the process we will be using for all of our examples. For the purposes of this handout we will refer to the user of Civil 3D who is using the subassembly as the “End User” and the user of the Subassembly Composer who is making the subassembly as the “User”. The six steps are: 1. 2. 3. 4. 5. 6.

Sketch the subassembly or ”the problem” Define the [Input/Output [Input/Outpu t Parameters] for the End End User Define the [Target Parameters] for the End End User Build the subassembly using the [Tool Box] Evaluate your subassembly and modify as necessary Import into AutoCAD® Civil 3D® 3 of 43


Example 1: Varying Shoulder 1. Sketch the subassembly or ”the problem”: In a typical shoulder and daylight scenario, we could have a constant shoulder and the daylight location on the target surface is calculated. In this first example, however, we instead have a known daylight target location (Offset) and the shoulder width is variable based on the shoulder slope and daylight slope. This scenario allows the End User to provide a large shoulder for future development within a pre-established right of way. There may be some instances where the End User wants to maintain a minimum shoulder width due to excessive cuts/fills. In which case, the offset target will not be used and an easement would be required. Using current Civil 3D functionality this could be obtained by finding the intersection generated from two surfaces (one temporary surface using a grading object with a feature line at P1 and generating the shoulder slope extended beyond the intersection, and one temporary surface using a grading object from a feature line at the desired daylight location with the target surface elevations and generating the daylight slope beyond the intersection). To find the intersection you would generate a volume tin between these two temporary surfaces and using the 0 elevation volum e contour as the target for the finished surface‟s shoulder location and then manually adjust for the minimum shoulder. This procedure is cumbersome and requires reanalyzing the shoulder target at every change in design. Instead, we can create a single dynamic corridor model using Subassembly Composer that will save us a great deal of time. We will first define the [Packet Settings], which includes the Subassembly Name, Description, Help File, and Image. This information will be shown on the Tool Palette once imported into Civil 3D. The Help File and Image are optional however to add them simply click on the […] button to the right of the entry field to browse to the location.

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2. Define the [Input/Output Parameters] for the End User: For each variable that we want the End User in Civil 3D to have ability to change we must define an input parameter. The first line in the Input/Output Parameters tab will always be filled in for you with “Side.” If you wish to disable this parameter for the End User, set the Default Value as “None.” In this example we will draw the curb as if it is on the right side and if the End User switches the Side to Left then the subassembly will mirror itself as defined. The first four columns (Name, Type, Direction, and Default Value) must be filled in. The last two columns (DisplayName and Description) are optional. If no DisplayName is provided, the Name will be displayed for the End User in Civil 3D. There are a total of eight Input/Output Parameter Types provided in the program (you can make more types using Enumeration which we will discuss later). In this example we will be using Double numbers, which allow for decimal precision, alternatively you could limit the End User to inputting Integer numbers, which allows only whole number values. We will also be using Slope (Horizontal:Vertical), Grade (%), and String (text). For this example we will not be defining any Output Parameters. To add a parameter, click the words “Create parameter”. If you inadvertently add too many parameters, select the one you would like to delete and press the Delete key on your keyboard.

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3. Define the [Target Parameters] for the End User: There are three types of Targets that can be used: Offset, Elevation, and Surface. In this example we have two required targets that the End User must use. The first is the target offset for the daylight, and the second is the target surface. The offset target can be an alignment, polyline, feature line, or survey figure. Just like with the Input/Output Parameters, to add a parameter click the words “Create parameter”. If you inadvertently add too many parameters, select the one you would like to delete and press the Delete key on your keyboard.

4. Build the subassembly using the [Tool Box]: The full Flowchart is available at the end of the building procedure on page 14 for your reference. The building procedure has been provided in two columns, at left is the step by step procedure and at right is a commentary. a.

Drag and drop a Sequence element from the Workflow section of the [Tool Box] to the [Flowchart]. It will automatically connect to the Start element.

You will notice that all elements have multiple connection nodes, at any time you can click on a connection arrow and drag it to an alternate connection node.

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b.

Rename the Sequence by clicking once on the name of the element and changing it to PositiveVariables. The double click into the Sequence to add elements.

In this example there are two Input Parameters which the End User must enter as positive values. In order to avoid any logic errors we are first going to find the absolute value of these two inputted parameters and use those in the remainder of the calculations.

c.

Drag and drop a Define Variable element (DaylightSlope) from the Miscellaneous section of the [Tool Box] to the PositiveVariables sequence and set the properties as shown:

A variable is similar to an input parameter, however it is defined by you instead of the Civil 3D End User. Math.abs() is one of many math Visual Basic (VB) expressions that can be used in calculations. Additional math VB expressions can be found in the Appendix of this handout. The Cut/Fill Daylight Slope should be positive since in this subassembly the same slope will be used for cut and fill therefore the logic will define the + or – and not by the End User.

d.

Drag and drop a Define Variable element (MinShoulder ) from the Miscellaneous section of the [Tool Box] to the PositiveVariables sequence and set the properties as shown:

The Minimum Shoulder Width should be positive since the side is being defined by the Side parameter.

e.

Exit out of the Sequence click the Flowchart in the nest links at the top of the [Flowchart] panel.

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f.

Drag and drop a Decision element from the Workflow section of the [Tool Box] to the flowchart below the PositiveVariables Sequence. It will automatically connect to the Sequence element.

Since the two target parameters are required, we will provide an error message to the Panorama in Civil 3D alerting the End User if they try to run the corridor without these targets provided. To do this we will query whether the both targets have valid input.

g.

Define the Condition for the Decision as follows:

In order to test two elements at the same time we are using the ()AND() expression. In each set of parenthesis we are going to use a Subassembly Composer Application Program Interface (API) function called “IsValid” which is available for all of the Target classes. Additional API expressions are available in the Appendix of this handout. Note that if you click on the triangle flag in the upper right hand corner of the Decision element the Condition expression will remain visible.

h.

Drag and drop a Report Message element from the Miscellaneous section of the [Tool Box] to the right (false) side of the Decision element and define as follows:

If you hover over the Decision element you will see that the True is on the left and the False is on the right. An easy way to remember what side is true or false for a decision element is to think „Right side means it‟s wrong‟. We will want to give the End User an error if one or both of the targets are not valid. There are three types of Error Levels: Error, Informational, and Warning

If it connects to or from the wrong connection node, simply click on the connection arrow and press the Delete key on your keyboard, then hover over the Decision element and click on the False connection node and drag it to connect to the Report Error.

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i.

j.

Drag and drop a Point element (P1) from the Geometry section of the [Tool Box] to the left (true) side of the Decision element and let it keep its defaults of being located at the Origin and being named P1.

The origin is the geometry point that your subassembly will attach to when generating an assembly in Civil 3D.

Drag and drop an Auxiliary Point element (AP1) from the Auxiliary Geometry section of the [Tool Box] to below P1 and define as follows:

An auxiliary point or an auxiliary link are used for subassembly generation but are not displayed in Civil 3D. They are useful for intermediate geometry such as this case. In this example we will be placing the first auxiliary point at the minimum shoulder location and have added a Comment reflecting that. These Comments can be viewable in the [Preview] panel.

There are nine Geometry Types.

different

Point

Note that you can expand or collapse any of the Property elements by clicking on the triangle to the left (ex. Link). For any of the images provided in this handout that have a property collapsed, you can assume that the default values were utilized.

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k.

Drag and drop an Auxiliary Point element (AP2) to below AP1 and define as follows:

The second auxiliary point is located on the target surface at the target offset. We do not want to put a normal point at this location yet because we do not know if this point will be used or if it will be overridden with the minimum shoulder test. Note that the Delta X is purely for layout purposes and will not be used since this element is in a branch that has already tested that the TargetOffset is valid.

l.

Drag and drop a Decision element to below AP2 and define as follows:

This decision element tests to find if the slope between AP1 and AP2 (defined by the Point Class SlopeTo API Function AP1.SlopeTo (“AP2”) ) is steeper than the daylight slope provided by the End User. If it is not steeper, we will calculate the shoulder location using the target location. If it is steeper than the DaylightSlope variable, that means that the minimum shoulder value should be used and a new daylight location must be calculated. In order to provide a visual cue to the viewer of the flowchart, you can edit the True and False labels to act as a reminder of what the true and false mean. In this example, the false will calculate the hinge point and the true will use the minimum shoulder as the hinge point.

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m. Drag and drop a Point element (P2) to the left (true) side of the Minimum Shoulder Decision element and define as follows:

n.

Drag and drop a Point element (P3) to below P2 (Min Shoulder) and define as follows:

Note that the Slope expression reads as follows: IF(P2.distancetosurface(TargetSurface)>0, DaylightSlope, DaylightSlope)

We will first define the logic using the minimum shoulder. Since we already have an auxiliary point at the minimum shoulder hinge location, there is no need to recalculate the location, so we will simply match the location of AP1.

Since the DaylightSlope variable is positive, we will adjust the slope to be positive or negative using an IF statement. This statement tests to see if the vertical distance from point P2 to the target surface is greater than zero, if true then it is in fill and the negative slope should be used, if false then it is in cut and the positive slope should be used. If an expression becomes too long to be fully visible, simply click the […] button to the right of the expression to open the Expression Editor window to see the full expression.

-

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o.

Drag and drop a Point element (renamed to also be P3) to the right side of the Minimum Shoulder Decision element and define as follows:

This point is located at the target daylight. Since we already have an auxiliary point AP2 at that location, the point location does not need to be recalculated. The Subassembly Composer will not allow you to duplicate a point number in a branch of logic but you are allowed to duplicate a point number if they are in separate branches of logic. In order to maintain consistency we will continue to use P3 for the daylight point and P2 for the hinge point.

p.

Drag and drop an Intersection Point element (renamed to also be P2) from the Advanced Geometry section of the [Tool Box] to below P3 (Target Daylight) and define as follows:

An intersection point allows you to find the location where two slopes intersect which is perfect for this example. We want the first slope to be the shoulder grade and we want to second slope to be the daylight grade (either positive or negative as appropriate for if the situation is cut or fill respectively). For Slope 2 we have used an IF statement to test if the slope from AP1 to AP2 is greater than the shoulder grade. If true a positive daylight slope will be used and if false a negative daylight slope will be used.

Note that the Slope 2 expression reads in full as follows: IF(AP1.Slopeto("AP2")>ShoulderGrade, DaylightSlope, -DaylightSlope)

Slope 2 (the daylight slope) is extended meaning that it extends out of both sides of Point 2 and not just in one direction. Experiment with the extending and reversing slopes to find the combination that works best for your situation.

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q.

Drag and drop a Sequence element to below the current logic. It should automatically connect to either of the end elements, P3 (Daylight Override) or P2 (Calc Shoulder). Add an additional connection arrow so that the branched logic both uses the same sequence. Rename the Sequence as Links and double click into the Sequence to add elements.

Each element can only have one exiting connection arrow (with the exception of Decisions and Switches) but it can have multiple incoming connection arrows to combine logic.

r.

Drag and drop a Link element (L1) from the Geometry section of the [Tool Box] into the Links Sequence and define as follows:

Since we maintained consistency of point P2 being the hinge point, we can use the same link to define the shoulder for all scenarios. In this example we allowed the End User to define the Link Codes through an Input Parameter string, if we were hard entering the Link Codes here we would need to include the quotation marks (ex . “Top”, “Datum”)

s.

Drag and drop a Link element (L2) to below L1 in the Links Sequence and define as follows:

Like link L1, by maintaining consistent point numbers, we can use the same link to define the daylight link for all scenarios.

The PKT file will be available for download from the AU2011 CI4252 class website after the associated lecture is given.

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5. Evaluate your subassembly and modify as necessary: Before finalizing a subassembly it is important to pay attention to some key components in the [Preview] panel. In this example, the first thing that we want to do is select the checkbox for Codes. This will allow the codes which are assigned to the points, links, and shapes to display. For each example you want to check to make sure that the links have the desired link codes, that any points have the desired point codes, and that the shapes have the desired shape codes.

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The next thing to check for any subassembly with targets is that the subassembly is functional for all potential target values. You can easily assess the targets by either changing the preview value in the [Target Parameters] tab or by dragging the various targets in the [Preview] panel. Make certain you are previewing the geometry in Roadway Mode. In this example we will first make certain that the Target Offset is overridden when the minimum shoulder decision is triggered. Note that I have turned on the Comments to confirm which points are being used from the different branches of logic.

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We will also test different values of the TargetSurface. I have shown two examples below. I recommend for all subassemblies trying a large positive value, a large negative value, and then on either +/- side of every point, since these tend to be the areas where decision ranges are most likely to have errors.

6. Import into AutoCAD® Civil 3D®: Once you are ready to import your subassembly into the Civil 3D Tool Palette. Save your PKT file and open up Civil 3D. To import the subassembly go to the Insert tab in Civil 3D, expand the Import panel, and select Import Subassemblies. The Import Subassemblies window as shown on the following page will open. Browse to your PKT file and add it to a Tool Palette (in this example, I‟ve made a custom tool palette for all of my AU subassemblies).

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Here is the road assembly created using the stock Civil 3D subassemblies for the road (LaneSuperelevationAOR), curb (UrbanCurbGutterGeneral), and our custom VaryingShoulder subassembly:

In this picture of the corridor using this subassembly you can see on the northerly side of the road how the minimum shoulder was maintained and the target offset line (shown as a dashed red line) is overridden while on the southerly side of the road the target offset was maintained and the shoulder width varies.

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Example 2: Precast Concrete Curb 1. Sketch the subassembly or “the problem”: This is a construction detail for concrete curbing that our office frequently uses and while we can generate a proposed top surface that is similar, it does not include the radius at the top gutter edge. Therefore this is a good candidate for a Subassembly Composer generated subassembly. Like the previous example we will first define the [Packet Settings].

2. Define the [Input/Output Parameters] for the End User: The Subassembly Composer is unitless; however, once you import a file into Civil 3D it will use the default units (feet or meters) that Civil 3D is using when the subassembly is imported. In this example I will assume that it will be used in Civil 3D Imperial; however, you will notice I am going to ask the End User for the length and depth dimensions in inches instead of feet; pay attention when we are building the geometry because each of these values will be divided by 12 to build the subassembly in feet as required by the default units. As a reminder to myself, I like to suffix any variables that I am asking the End User to provide in inches with “IN” to remind myself to convert back into feet in the flowcha rt.

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3. Define the [Target Parameters] for the End User: For this example there are no Target Parameters which makes this step of the process simple. 4. Build the subassembly using the [Tool Box]: Before building the logic for your subassembly, it is sometimes helpful to draw in the points on your original sketch and number them sequentially (just like a “Connect The Dots” drawing) and similarly label each link between a pair of points. You will want a point at every change in direction of a link. As you can see by the finished sequence at right, we can‟t always define the points sequentially in the logic but it will make much more sense if your point numbers are continuous around a shape.

Similar to the last example, the building procedure has been provided in two columns, at left is the step by step procedure and at right is a commentary.

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a.

Drag and drop a Sequence element to below the Start element. Double click into the Sequence to add elements.

Because this is “straight line logic” (no decisions, always the same geometry) we are going to build the entire subassembly logic inside of a Sequence.

b.

Drag and drop a Point element (P1) into the Sequence and define as follows:

As previously stated, the Subassembly Reference is a good place to get help in deciding point codes. Unlike the last example, because the code is being defined by the End User and is not a string input parameter, we must place the quotes around the word to convert it into a string.

c.

Drag and drop an Auxiliary Point element (AP1) to below P1 in the Sequence and define as follows including the creation of Auxiliary Link element (AL1):

Point AP1 will be placed at the point of intersection for the front radius curve. In order to draw the radius we will need to remember that since all of the Input Parameters are in inches, we are dividing the dimensions by 12 to convert the subassembly into feet. With each point or auxiliary point there is the option to add a link or auxiliary link from the “From Point” to the point or auxiliary point being generated. In this case we will soon be defining the front radius link between two links so we will take this opportunity to define the first of these two auxiliary links needed later.

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d.

e.

Drag and drop an Auxiliary Point element (AP2) to below AP1&AL1 in the Sequence and define as follows including the creation of Auxiliary Link element (AL2):

Similar to AP1, this will be the point of vertical intersection for the back radius curve.

Drag and drop a Fillet Arc element (renamed L2) from the Advanced Geometry section of the [Tool Box] to below AP2&AL2 in the Sequence and define as follows including the creation of Point elements (renamed P2 and P3):

Now that we have an auxiliary link for each tangent of the front radius we can define the fillet arc link between the two auxiliary links and at the same time generate the points at the points of tangency

In addition, we will once again create an auxiliary link to be used in defining both the front and back radius links.

The tessellation of an arc is the number of segments that are generated to create the arc.

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f.

Drag and drop a Link element (renamed L1) to below L2&P2&P3 in the Sequence and define as follows:

This generates a link at the face of curb.

g.

Drag and drop a Point element (renamed P6) to below L1 in the Sequence and define as follows:

This point is located at the back bottom of curb. We are not generating a link at this time from AP2 to P6 because we do not need/want the link to extend above the radius instead we want to generate an auxiliary link. You cannot create an auxiliary link at the same time as a point, or a link at the same time as an auxiliary point.

h.

Drag and drop an Auxiliary Link element (AL3) to below P6 in the Sequence and define as follows:

This will create the auxiliary link referenced in the previous step. AL2 and AL3 will be used to generate the back radius link.

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i.

Drag and drop a Fillet Arc element (renamed L4) to below AL3 in the Sequence and define as follows including the creation of Point elements (renamed P4 and P5):

This step will generate the fillet arc link for the back of the curb just like the fillet arc link L2 was generated for the front of the curb. In this example I have chosen to define this back arc with the “Top” link code and anticipate connecting a shoulder surface to point P5.

j.

Drag and drop a Link element (renamed L3) to below L4&P4&P5 in the Sequence and define as follows:

We will continue to add the points and links as originally sketched.

k.

Drag and drop a Link element (L5) to below L3 in the Sequence and define as follows:

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l.

Drag and drop a Point element (renamed P7) to below L5 in the Sequence and define as follows including the creation of Link element ( L6):

m. Drag and drop a Link element (L7) to below P7&L6 in the Sequence and define as follows:

n.

Drag and drop a Shape element (S1) from the Geometry section of the [Tool Box] to below P7&L6 in the Sequence and define as follows:

When adding a shape element you must have a closed set of links. To pick the shape, do not take time to figure out the name of each link and try to Add Link and type in the links, instead click the green selection icon to the right of the entry field and click on the shape in the [Preview] panel, just like you would when defining a hatch in AutoCAD. If you want to change to a different shape simply select the green selection icon again and reselect the new shape, the list of links will update for you.

The PKT file will be available for download from the AU2011 CI4252 class website after the associated lecture is given.

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5. Evaluate your subassembly and modify as necessary: Like the previous example you will want to check that Codes are properly assigned. 6. Import into AutoCAD® Civil 3D®: Like the previous example you will import the subassembly into a Civil 3D Tool Palette using the Import Subassemblies command. Here is the road assembly created using the stock Civil 3D subassemblies for the road (LaneSuperelevationAOR), our custom precast concrete curb subassembly, shoulder (LinkWidthAndSlope), and daylight (LinkSlopeToSurface):

Here you can see the tessellation points created by the fillet arc as shown in the assembly:

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Example 3: Link Max Slope 1. Sketch the subassembly or “the problem”: A person reviewing my plans recently came to me and informed me that there was a horrible error with my plans. They were scaling perpendicular to the daylight contours and noticed that the horizontal distance across a 3‟ vertical change was 5.85‟ which was steeper than the acceptable 2:1 (it was in fact 1.95:1). I kindly pointed out that the slope is drawn based on the road cross section which scaled as 6.00‟, as expected. After much discussion there was just no agreeing to be had and so I did a quick and dirty fix and set the cross slope to 2.1:1 instead of 2.0:1 and everything was conservatively larger than the acceptable 2:1. This problem arose because the slope of the baseline profile and the perpendicular cross slope combine to make the slope as measured perpendicular to the contours. When I learned that the Subassembly Composer could perform calculations using an API Function for the baseline grade I knew that the problem could finally be dynamically solved. In order to calculate the link slope based on the profile slope and the maximum allowable slope we are going to turn to the rules of geometry. We will draw a triangle with leg AC parallel with the profile baseline and leg AB perpendicular to the profile baseline. We will define points B and C along the same contour. We will ultimately want to find the value of the slope along leg AD (S AD) in terms of S AD (the maximum allowable slope) and S AC (the profile baseline slope) which are both known values. Since the elevation along line BDC is all the same therefore the elevation change from A to D is the same as the elevation change from A to C, therefore

 L S    L S  . AD

AD

AC

AC

Since S AD

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and S AC are known values and we can assume that L AC is known based on the elevations assumed for A, B, and C, we can solve for L AD:

L AD



 L S  . The triangle AD-DC-CA S  AC

AC

AD

is

a

right

 L 

2

AD

LCD



triangle

( LCD )

2

which 

  L 2  ( L ) 2 . AC

AD

L  AC

can 2

be

defined

by

the

Pythagorean

Theorem:

. Since now L AC and L AD are known, we can solve for L CD:

The triangle ABC and triangle DAC are similar triangles with the

same angles therefore their sides are ratios of one another which can be defined as L AB L AC L AB

 

L AD LCD

. Since now L AC, L AD, and L CD are known, we can solve for L AB:

 L  L  AD

AC

LCD

. As originally stated, the elevation along line BDC is all the same,

therefore the elevation change from A to B is the same as the elevation change from A to C, therefore  L AB S AB    L AC S AC  . Since L AB, L AC, and S AC are all known values, we can

 L S  . Filling in the solved equation for L AB and simplifying, we get  L  S  L   . Filling in the solved equation for L CD and simplifying, we get that  L 

solve for S AB:



S AB

AC

AC

AB

that

S AB

AC

CD

AD

S AB

S   L 2  ( L   L  AC

AC

AD

)

2

. Filling in the solved equation for L AD and simplifying, we get

AD

the final solution of S AB using the known S AC and S AD:

S AB

 S

AD

 S  1    S

  

AC AD

2

Note that we

are keeping S AC such that the sign (+/-) of this slope is maintained if needed, if we do not want to maintain the sign then we will use the absolute value of S AC. So what does this really mean? It means that if the profile grade is 0% then the calculated link slope will equal the maximum allowable grade, but as the profile grade increase (or decreases) then the link grade will decrease to maintain the maximum allowable grade. This is displayed in the following table. Calculated Link Grade (%) Maximum 20.0% Allowable 25.0% Grade (%) 33.3% 50.0%

0.0% 20.0% 25.0% 33.3% 50.0%

5.0% 19.4% 24.5% 33.0% 49.7%

Profile Grade (%) 10.0% 17.3% 22.9% 31.8% 49.0%

12.0% 16.0% 21.9% 31.1% 48.5%

15.0% 13.2% 20.0% 29.8% 47.7%

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There are five link stock Civil 3D subassemblies that have an input parameter for slope. In this example we will modify the LinkSlopeToSurface stock subassembly. Currently none of the stock subassemblies can be directly opened in Subassembly Composer and modified. Instead we will modify it by looking at the help file and using similar parameters, targets, and terminology. Like the previous example we will first define the [Packet Settings].

2. Define the [Input/Output Parameters] for the End User: We will match our Input Parameters to those used by the LinkSlopeToSurface stock subassembly with the exception of Slope which instead of the link slope we will instead ask the End User for the maximum allowable slope of the surface.

You will note that the AddLinkIn input parameter has a unique type that has been named CutsFills, this is called Enumeration and is defined by the Subassembly Composer User. To define an enumeration, go to the View menu and select Define Enumeration. Create an Enumeration Group named CutsFills and create three enumeration items as follows:

Once the CutsFills Enumeration Group is created it will show up as an option in the Input Parameter Type dropdown menu. We will not be using any of the output parameters for this example. 28 of 43


3. Define the [Target Parameters] for the End User: For the target parameters we will also match those used by the LinkSlopeToSurface stock subassembly.

4. Build the subassembly using the [Tool Box]: a.

Drag and drop a Define Variable element (ProfileSlope ) to the [Flowchart] and define as follows:

This variable takes the instantaneous slope of the baseline being used by the corridor and finds the absolute value. Baseline.grade is an API Function in the Baseline Class. Other baseline API Functions include station, elevation, region start, region end, and turn direction. The ability to query the baseline is not currently available in any of the stock subassemblies.

b.

Drag and drop a Decision element to below the ProfileSlope and define as follows:

This decision will test whether the profile slope already exceeds the input parameter that the End User defined as the maximum allowable slope of the surface.

c.

Drag and drop a Report Message element to the left (true) side of the Decision and define as follows:

If the profile slope exceeds the maximum allowable slope for that cross section this error message will be displayed in Civil 3D‟s panorama.

Note that the Message expression reads as follows: Slope of baseline exceeds Maximum Allowable Slope

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d.

Drag and drop a Define Variable element (LinkSlope ) to the right side of the Decision and define as follows:

This variable defines the link slope based on the equation we previously calculated.

S AB

 S

AD

 S  1    S

Math.abs(MaxSlope)*math.sqrt(1math.pow(ProfileSlope/MaxSlope,2))

e.

Drag and drop a Point element ( P1) to below the LinkSlope and define as follows:

f.

Drag and drop a Decision element to below P1 and define as follows:

2

AC

AD

Note that the expression reads as follows:

  

By adding this element to any subassembly you can use maximum slope instead of the slope perpendicular to the baseline. If we had not previously defined the ProfileSlope variable we could alternatively use the baseline.grade API Function in this VB expression in place of ProfileSlope.

This decision will define whether we are in cut or fill since we will want to perform different logic for cut and fill based on the CutsFills input parameter.

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g.

Drag and drop a Decision element to the left (true/Fill) side of the Cut/Fill Decision and define as follows:

If in fill then we want to confirm whether the End User has defined the AddLinkIn input parameter as either CutAndFill or Fill Only. (If false we will perform no logic.)

h.

Drag and drop a Point element (P2) to the left side of the Fill‟s AddLink Decision and define as follows:

The point will be generated from P1 using the negative value of the LinkSlope variable since we are in fill.

i.

Drag and drop a Decision element below P2 (Fill) and define as follows:

This decision confirms whether the End User has defined the OmitLink input parameter as Yes. (If true we will perform no logic.)

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j.

Drag and drop a Link element (L1) to the right (false) side of the Fill‟s AddLink‟s OmitLink Decision and define as follows:

If the End User has not set the OmitLink input parameter to Yes then we will generate the link from point P1 to P2 and use the codes that the End User has provided through the LinkCode input parameter in addition to a “Daylight_Fill” link code.

k.

Drag and drop a Decision element to the right (false/Cut) side of the Cut/Fill Decision and define as follows:

Note that steps k. through n. are a repeat of steps g. through j. for the cut scenario instead of fill. If in cut then we want to confirm whether the End User has defined the AddLinkIn input parameter as either CutAndFill or Cut Only. (If false we will perform no logic.)

l.

Drag and drop a Point element (renamed to also be P2) to the left (true) side of the Cut‟s AddLink Decision and define as follows:

The point will be generated from P1 using the positive value of the LinkSlope variable since we are in cut.

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m. Drag and drop a Decision element below P2 (Fill) and define as follows:

This decision confirms whether the End User has defined the OmitLink input parameter as Yes. (If true we will perform no logic.)

Drag and drop a Link element (L1) to the right (false) side of the Cut‟s AddLink‟s OmitLink Decision and define as follows:

Just like in fill, if the End User has not set the OmitLink input parameter to Yes then we will generate the link from point P1 to P2 and use the codes that the End User has provided through the LinkCode input parameter in addition to a “Daylight_Cut” link code.

n.

The PKT file will be available for download from the AU2011 CI4252 class website after the associated lecture is given. The finished flowchart should look similar to the following:

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5. Evaluate your subassembly and modify as necessary: Like the previous example you will want to check that Codes are properly assigned and that it behaves as expected for various values of the Input Parameters and Target Parameters. 6. Import into AutoCAD® Civil 3D®: Like the previous example you will import the subassembly into a Civil 3D Tool Palette. And the sketch that the person complained had contours closer than 2:1, now looks like this:

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Example 4: Backwards Engineering There is going to be a point in the future that you are going to come across a PKT file that you made months ago or a PKT file that someone else made. Most likely you are opening up this mysterious PKT file because you have found a mistake in how it behave in Civil 3D or you want to edit it for different Civil 3D capabilities. So instead of building the subassembly you are going to have to understand how the subassembly was built. In this last example, instead of going through the six step workflow we are going to look at a subassembly that I previously created and understand how to make sense of the logic.

Parabolic Rounding With Daylight Fillet This example provides parabolic rounding at the Point of Vertical Intersection (PVI) between the shoulder and daylight links as well as fillet rounding between the daylight link and target surface. In addition, the End User is provided the option to either define the shoulder width dimension from the origin to the PVI (P1 to P2, as currently designed) or from the origin to the Beginning of Vertical Curvature or BVC (P1 to AP3). The flowchart is provided on page 38 and the PKT file is available for download from the AU2011 CI4252 class website after the associated lecture is given. The Input Parameters are as follows:

The ShoulderDefine type has two options: BVC and PVI and allows the End User to select what point their Shoulder Width measures to. The Target Parameters are as follows:

The DisplayName acts not only as clear and concise language to the Civil 3D End User but it also acts as a comment for the Input Parameter. The Name and the DisplayName are often similar with spaces added in for the DisplayName. However, you will note that in this example the DisplayName is helpful in learning that Grade1 refers to the shoulder grade and Grade2 refers to the daylight grade. 35 of 43


It is always important to turn on the Comments to see if there is any additional information that the original User provided. Here is the Preview Panel with the Comments turned on:

You will notice that sometimes the text becomes hard to read when there are lots of points or links. Zooming in will help. In addition if you click on any element in the [Preview] panel the [Properties] panel will update accordingly. The image at right shows the Comments turned on and the Codes turned off. The Comments will always be shown in parentheses () and the Codes will always be shown in brackets []. When evaluating a subassembly in the [Preview] panel it is sometimes helpful to temporarily create a couple of test target parameters to act like grid lines as shown below. The targets will not be associated with any logic. By dragging these temporary target gridlines to various locations, the value of the offsets and elevations of various points will be displayed in the [Target Parameters] panel. Just don‟t forget to delete these temporary targets before saving and importing into Civil 3D.

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To analyze a flowchart it is best to start at the top and analyze down one branch at a time. By deleting some connection arrows, you can view only the logic that is connected to the Start element. By disconnecting and connecting several elements you can slowly begin to see how the geometry is built. Remember that you may need to change some of the Input or Target Parameters to make one of the branches of logic applicable. This can be done by dragging targets, changing the Preview value of the Target Parameters, or changing the Default value of the Input Parameters When imported into Civil 3D and attached to an assembly, the subassembly will be displayed as follows:

By increasing the value of the Input Parameters for Parabola Horizontal Length and Daylight Rounding Length you can get a different look as shown in the two images below.

The entire flowchart is shown on the following page. I challenge you to look through it and see what makes it work.

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Endless Possibilities In conjunction with the stock subassemblies already available in the Civil 3D tool palette and the subassemblies you create with the tool box in the Subassembly Composer, your corridors will have endless possibilities. The best way to learn a program is by using it, so go ahead and download the Subassembly Composer for Civil 3D 2011 & 2012 to your computer if you haven‟t already. Start by composing a simple subassembly using Subassembly Composer. Before you know it your mind will be opened to a whole different way of approaching corridors in your design.

For Further Assistance 1.

Autodesk ® WikiHelp for Autodesk Subassembly Composer: http://wikihelp.autodesk.com/AutoCAD_Civil_3D/enu/2012/Help/Auto desk_Subassembly_Composer

2.

Autodesk ® Discussion Groups for AutoCAD Civil 3D: http://forums.autodesk.com/t5/AutoCAD-Civil-3D/bd-p/66

3.

AutoCAD Civil 3D Subassembly Reference: http://images.autodesk.com/adsk/files/c3dstocksubassemblyhelp.pdf

4.

Twitter hashtag: #SACCivil3D

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APPENDIX VB Expressions: Math Emphasized values can be changed to reference the applicable value.

Sample VB Expression math.round(2.568 ,2 )

Output 2.57

math.floor(2.568 )

2

math.ceiling(2.568 )

3

math.max(2.568 ,0.813) math.min(2.568 ,0.813) math.abs(-2.568 ) math.pi math.e math.sin(math.pi )

2.568 0.813 2.568 3.14159... 2.71828... 0

math.cos(math.pi )

-1

math.tan(math.pi )

0

math.asin(1)

1.57079...

math.acos(1)

0

math.atan(1)

0.78539...

math.log(math.e)

1

math.log10(10 ) math.exp(1) math.pow(2 ,3) math.sqrt(81)

1 2.71828... 8 9

Description Returns a value rounded to the nearest specified decimal places (ex. -2 = hundreds, -1 = tens, 0 = whole number, 1 = tenths, 2 = hundredths, etc. ) Returns the largest integer that is less than or equal to the specified value (i.e. rounds down) Returns the smallest integer that is greater than or equal to the specified value (i.e. rounds up) Returns the larger of a series of two specified values Returns the smaller of a series of two specified values Returns the absolute value Returns the value of the constant pi Returns the value of the constant e Returns the sine of a specified angle measured in radians Returns the cosine of a specified angle measured in radians Returns the tangent of a specified angle measured in radians Returns the angle measured in radians whose sine is the specified value Returns the angle measured in radians whose cosine is the specified value Returns the angle measured in radians whose tangent is the specified value Returns the natural (base e) logarithm of a specified value Returns the base 10 logarithm of a specified value Returns e raised to the specified power Returns a value raised to the specified power Returns the square root of a specified value

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VB Expressions: Logic Emphasized values can be changed to reference the applicable value. IF(P1.Y>P2.Y ,2 ,3)

P1.Y >P2.Y P1.Y >=P2.Y P1.Y P2.Y (P1.Y>P2.Y )AND(P2.X>P3.X ) (P1.Y>P2.Y )OR(P2.X>P3.X )

(P1.Y>P2.Y )XOR(P2.X>P3.X )

Used in a VB Expression, returns a value depending on whether the condition (P1.Y>P2.Y ) is true (value of 2 ) or false (value of 3) A condition that returns true if P1.Y is greater than P2.Y A condition that returns true if P1.Y is greater than or equal to P2.Y A condition that returns true if P1.Y is less than P2.Y A condition that returns true if P1.Y is less than or equal to P2.Y A condition that returns true if P1.Y is equal to P2.Y A condition that returns true if P1.Y is not equal to P2.Y A condition that returns true if both the condition (P1.Y>P2.Y ) AND the condition ( P2.x>P3.X ) are true A condition that returns true as long as either the condition (P1.Y>P2.Y ) OR the condition (P2.x>P3.X ) is true A condition that returns true if only one of the two conditions (P1.Y>P2.Y ), (P2.x>P3.X ) is true (if both are true or both are false, then false is returned)

VB Expressions: Subassembly Composer Application Programming Interface (API) Functions Emphasized values can be changed to reference the applicable element. Points and Auxiliary Points Class P1.X P1.Y P1.Offset P1.Elevation P1.DistanceTo(“P2 ”) P1.SlopeTo(“P2 ”)

Horizontal distance from point P1 to Origin Vertical distance from point P1 to Origin Horizontal distance from point P1 to assembly baseline Elevation of point P1 relative to 0 Distance from point P1 to point P2 ( Always positive) Slope from point P1 to point P2 (Upward = positive, Downward = Negative) P1.IsValid Point P1 assigned and valid to use (True/False) P1.DistanceToSurface( SurfaceTarget ) Vertical distance from point P1 to SurfaceTarget ( point above = positive, point below = negative )

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Links and Auxiliary Links Class L1.Slope

L1.Length L1.Xlength L1.Ylength L1.StartPoint L1.EndPoint L1.MaxY L1.MinY L1.MaxInterceptY(slope) L1.MinInterceptY(slope) L1.LinearRegressionSlope L1.LinearRegressionInterceptY L1.IsValid L1.HasIntersection(“ L2 ”) L1.HasIntersection(“ L2 ”, true, true)

Offset Target Class OffsetTarget .IsValid OffsetTarget .Offset

Elevation Target Class ElevationTarget .IsValid

ElevationTarget .Elevation

Surface Target Class SurfaceTarget .IsValid

Slope of link L1 Length of link L1 ( Always positive) Horizontal distance between start to end of link L1 ( Always positive) Vertical distance between start to end of link L1 ( Always positive) A point located at the start of link L1 (Can be used in API Functions for P1 Class) A point located at the end of link L1 (Can be used in API Functions for P1 Class) Maximum Y elevation from a link‟s points Get the minimum Y elevation from a link‟s points Apply the highest intercept of a given link‟s points to the start of another link Apply the lowest intercept of a given link‟s points to the start of another link Slope calculated as a linear regression on the points in a link to find the best fit slope between all of them The Y value of the linear regression link Link L1 is assigned and valid to use ( True/False) L1 and L2 have an intersection, second input is a Boolean defining whether to extend L1 with default of false, third input is a boolean defining whether to extend L2 with default of false ( True/False)

OffsetTarget is assigned and valid to use ( True/False) Horizontal distance from OffsetTarget to assembly baseline

ElevationTarget is assigned and valid to use (True/False) Vertical distance from ElevationTarget to assembly baseline

SurfaceTarget is assigned and valid to use (True/False) 42 of 43

Create Subassemblies That Think Outside the Box With Subassembly Composer for AutoCAD® Civil 3D®

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