Superelevation Part 2: Assembly and Subassemblies

December 6, 2023 Leo Lavayen

Building off the previous post, Superelevation Part 1, this post will focus the attention on the typical section design:  Assembly and Subassembly.  The key here is to make sure design values set from calculating Superelevation are assigned.

The Assembly:
From the Assembly Properties dialog box > Construction tab > set the Assembly Type from the drop-down selection:
The Assembly Type selected must match the type Roadway Type selected when in the Calculating Superelevation wizard:

The Subassemlby:
The important part here is to use Subassemblies that have been coded to leverage Superelevation calculated values.  As a bad example, the Basic Lane subassembly, found the Basic tab.  It has NO out of the box fields encoded to work with a superelevation:

 A better example, in design choice would be the Lane Superelevation AOR subassembly, found in the Lanes tab.  Design slope will default to the 2% slope, and apply Superelevation grade values.  Take special notice of the “Use Superelevation” drop down in the AutoCAD Properties palette below:

 The same values can be access from the Civil 3D using the more specific Assembly or Subassembly  properties dialog boxes: 

The most common mistake users get into is setting the incorrect Superelevation values.  Depending on the complexity, set the correct “Left vs Right” side or “Inside vs Outside” values are referenced:

With all the check list items in their place, the Corridor will process the Superelevation Design values, and display them in the Sections:
1.    Alignment design speed set.
2.    Superelevation calculated for the alignment.
3.    Assembly type must be selected.
4.    Subassembly values need to be set.

Notice below section at  STA 690 (left) is in the middle of a Curve, showing the calculated superelevation grades of 4.00%.  And how section at STA. 780 (right) is outside of the Curve and it shows the default 2.00% grade.


This give us the correct slopes on the Pavement sections.  Please see the next post for how to leverage more design details:
    Part 3:  Spilling the Gutters
•    Part 4:  Rolling off the Shoulders

For more blogs such as this, please visit our IMAGINiT Civil Solutions Blog Page.

About the Author

Leo Lavayen

Civil Applications Expert<br><br>As an Applications Expert, Leo is responsible for supporting, training and implementation of software for survey and civil engineering professionals. He has more than 19 years of experience helping large and small, public and private clients in the eastern United States.

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