Dynamic Civil 3D Offset Alignments and Widenings

June 24, 2020 Richard Morrow

In this Blog I wanted to show how Offset Alignments are dynamically linked to a “parent” alignment within Autodesk Civil 3D. This makes them perfect for defining linear geometry that would otherwise need to be redrawn as a design change. Widenings can use offset Alignments to accommodate things like turn lane transitions. No matter how offset Alignments are defined, they will always maintain a geometric relationship with their parent Alignment. This saves time from rebuilding the offsets on future design modifications.

Build Offset Alignments

Use the Offset Alignment command to build your Offset Alignments. Then define your offsets on the Create Offset Alignment dialog.


You have now created your Offset Alignments. They maintain a dynamic relationship with centerline Alignment.


Create Widenings

Use the Add Widening command to create the control line for the lane widening.


Set the Widening and Transition parameters. Remember that the distance is from your parent Alignment. You can use the grips or dialog to adjust your transition. Also, use the add + grip to add a widening to a widening. You can have a linear or curved transition.


You now have an Offset Alignment which you can use to control your lane widenings that is dynamic as you can see below.


Using Dynamic Offsets can save you a lot of time by automatically reacting to the parent Alignment when design changes occur.

About the Author

Richard Morrow

Civil Solutions Application Expert<br><br>Richard is responsible for Training and Services around Infrastructure. He has extensive experience in numerous Autodesk products, including Vault, Civil 3D, InfraWorks and BIM360. He joined IMAGINiT when it acquired Advanced Solutions. His past work experience includes working at Autodesk as a Technical Account Manager.

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