Bowties be Gone

Apparently Matt’s on a hot streak, two in a row for our Canadian contributor! JW

I’m willing to bet if you’ve had a little more than zero experience with corridors you know what Bowties are.  maybe not in name, but in practise.  Bowties are what happens when your corridor has a bend in it that is too tight for the width of the section.  Here’s an image.  The circle shows overlapping links.


This is a perfectly understandable phenomena; each corridor section is its own standalone entity without thought to preceding or successive sections.  Same thing happened in Land Desktop, it’s just that there was no Corridor in LDT so it wasn’t blatantly obvious.  Additionally, this overlap condition is not problematic unless you’re creating a surface.  This is Civil 3D after all and it’s all about making surfaces; far more than Land Desktop, at least in my experience. Make the jump to find an alternate solution.

You may have heard about a workaround.  In the Bowtie area, use an assembly without a daylight.  Use a feature line and a grading object to do the daylight for you.  That’s fine, but then how do you complete your surface and its boundary easily?

  1. Split the region a couple of times and place the assembly with no daylight in that new region.
  2. Make your corridor surface and make sure to set the boundary so this area is not included.  Use the Corridor extents as outer boundary option.
  3. Extract a feature line and maintain the dynamic link to the corridor.
  4. Grade the feature line to surface in this area only.   Make sure your grading group is set to create the surface automatically.
  5. Create a new surface and paste both the corridor and grading surfaces into it.  You’re done!  Any change to the corridor will reflect in the grading, its surface, and the pasted surface.

Let me know how this works for you.

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