Modeling Medians using AutoCAD Civil 3D Corridors

Despite their frequent placement in roadway designs, modeling medians in AutoCAD Civil 3D is anything but a clear-cut process. Asking a half-dozen Civil 3D users how they approach the task will likely yield just as many answers. An excellent collection of Median subassemblies has shipped with the software for years. Despite this, I’ve found few who put them to use on projects.

I think one reason for this is because how to apply the out-of-the-box Median Subassemblies isn’t the most obvious workflow in the world. Furthermore, knowing how the Subassemblies work is often just half the battle. Building your Corridor model in a way the Subassemblies can be applied can be just as complicated as knowing how they work.

Although the Median Subassemblies work the same in AutoCAD Civil 3D 2018 as they do in previous releases, the 2018 version offers some key features to simplify the process of modeling medians. Before 2018, designers had to manually establish an alignment and profile for each side of a median. That process could be tricky since the profile for medians is typically linked to the cross slope of the road it divides.

This is where features added to Civil 3D 2018 dramatically simplify the median modeling process. Starting with Civil 3D 2018, we are now able to create Offset Alignments that also have a dynamically associated Offset Profile. That means the profile elevation data assigned to your Offset Alignments is dynamically linked to your centerline profile. A change to the centerline profile elevations will also update the offset profile elevations. In other words, Offset Profiles work like the dynamic relationships between just about every other Civil 3D object; points and surfaces, surfaces and profiles, and the list goes on.

Check out the video above to see this process in action, and let us know your ideas for applying this modeling concept to your projects in the comments below.