Enabling Transitions between Duct Bank Sections with Subassembly Composer

In a previous post, we discussed building a basic duct bank subassembly. That subassembly was restricted to one width and one depth. For simplicity, in this post we will leave out the conduit locations and focus only on the concrete encasement and configure input parameters to control its length and depth.

Suppose we have a duct bank that changes its shape from a 1×2 to a 2×1 concrete encasement.

If we would employ two different subassemblies for this scenario, we will end up with this:

And if we try to create a gap between regions, we will end up with this:

We need to use one assembly so we can stick with one region throughout the length of the duct bank, one assembly that can change the width and depth of the concrete encasement.

Using the instructions from the previous post, we can create the necessary links for the concrete encasement, stopping at S1 since we are not configuring conduits in this exercise.

Since we need to be able to change the width and depth at any time, we will create two input parameters:  Width and Depth. Input parameters allow you to specify dimensional variables when placing a subassembly.

On the Input/Output Parameters tab in the lower left panel in Subassembly Composer, click Create Parameter twice to create a parameter for Width and one for Depth. Configure them as shown below:

Next, we need to edit the links L1 through L4 to use the Width and Depth input parameters.

1. In the Flowchart, click on P2&L1.
   
   This is the segment which locates where the top right corner of the duct bank relative to the alignment:  Width/2

2. Configure the Delta X value of P2&L1 to be Width/2.
   
3. In the Flowchart, click on P3&L2.
   
   This is the segment which locates where the bottom right corner of the duct bank is relative to P2:  -Depth
4. Configure the Delta Y value of P3&L2 to be -Depth.
   
5. In the Flowchart, click on P4&L3.
   
   This is the segment which locates where the bottom left corner of the duct bank is relative to P3:  -Width

6. Configure the Delta X value of P4&L3 to be -Width.
   
7. In the Flowchart, click on P5&L4.
   
   This is the segment which locates where the top left corner of the duct bank is relative to P4:  Depth

8. Configure the Delta Y value of P5&L4 to be Depth.
   
9. On the Packet Settings tab in the lower left panel in Subassembly Composer, type in a Subassembly Name ensuring that there are no spaces in the name:
   

Next, we will import the subassembly into AutoCAD Civil 3D, add it to an assembly base line, and configure it to a corridor representing the duct bank.

10. To import a custom subassembly into AutoCAD Civil 3D created in Subassembly Composer, on the Insert tab on the ribbon, locate the Import panel and click Import Subassemblies.
    
11. Browse to the PKT file we just created and click OK.
    
12. Create a new assembly and add the custom subassembly we just imported. Notice the Input Parameters we just created.
    
13. Create a corridor using the assembly we just created. Remember that you must have an alignment and a design profile representing the duct bank we are about to create.
14. Select the corridor and on the contextual ribbon, click Split Region.
    
15. Click on or enter the station value where the duct bank will fully transition.
16. Select the corridor and on the contextual ribbon, click Edit Section.
17. In the Section Editor ribbon on the Station Selection panel, set the station current where the transition will occur.
18. In the Section Editor ribbon on the Corridor Edit Tools panel, click Parameter Editor.
19. In the Corridor Parameters palette, change the Depth and Width parameters to 1 and 2 respectively.
    
20. On the Section Editor ribbon on the Corridor Edit Tools panel, click Apply to a Station Range.
    
21. In the Apply to a Range of Stations dialog, configure an end station value where the new section dimension will end.
    
22. Click Close on the Section Editor ribbon.
    
23. Notice how the corridor changes shape from the previous section to the transition section we just created.
    

Transitioning corridors into various shapes enables us to adapt to real world scenarios when a typical design must change along its alignment. Introducing new assemblies into corridors is not always necessary nor will it give us the desired result. Being able to develop transitional regions will help us translate the intent of the design.

 – Cyndy Davenport