Corridor Basics – 1

In AutoCAD Civil3D, I think new individuals are a bit intimidated by certain C3D objects. One of those objects is the oft complex corridor objects. When working with corridors, it is important to grasp the breakdown of the corridor model.

I thought I would take a brief look at what a corridor is and all the pieces that make up a corridor. First, what is a corridor?

A corridor is simply a 3D model of a linear path.

What makes it a 3D model are three important elements – a linear path (horizontal and vertical) and what 3D shape to apply along said path. THAT IS IT!!

The linear path for a corridor is defined by an alignment and profile. What 3D shape to apply along said path is defined by an Assembly object.

An Assembly object is made up of subassembly objects.

A subassembly object is made up of three items:

  • Markers
    • These are the points that connect links sectionally (did I just create a word?) and also connect to create 3D Feature Lines longitudinally along the linear path.
  • Links
    • These are lines that connect markers in a sectional view
  • Shapes
    • When links close to create a polygon, you have a shape

All three items can be or are named. This is important for many reasons. One reason is it gives you the ability to control the display of your markers, links, and shapes from the Code Set Style associated with the subassembly (which in most cases derives its code set style form the assembly).


  1. Tom Snyder says:

    I don’t do road/transportation, but I’m trying to understand for future growth and opportunities. Please bare with me on what may be some silly questions.

    You had me all the way to “3 items can be or are named”. What kind of naming convention does it take or already have, such as stationing maybe? And what is a Code Set Style?

    If assembles are made-up of subassemblies, then the subassemblies are the layers of earth, base, and road type things (pic above). And the assemble (first pic above)is the subassembly that’s linked to the surrounding surface area that runs perpendicular within the corridor linear layout? Is this even close to describing basic relationships of these features?

    Thanks for the basic knowledge.

  2. Kimberly Angus says:

    Basically summed it up pretty well. Take time to venture thru your tool palette (Ctrl+3).

    The best thing you can do is run thru the tutorials and catch a few web casts on the subject. If you don’t already have a Mastering Civil 3D book, get one. Civil 3D 2010 has greatly improved intersections. (Thanks Guys!)

    To answer your question on the “named or can be named” – drop in an assembly, right click and open assembly (or subassembly) properties, click on the Codes tab… when you create your own, you have the option to name them…