Deleting Feature Line Breaklines from a Surface with a Multiple Breakline Definition

Okay it’s a tough title to digest but don’t worry, this will simply be a short quick tip post.

If you’re like me, you sometimes take the easy way out when adding feature line breaklines to a surface definition and select a bunch of feature lines with one crossing window. The trouble begins when you need to remove just one or two of those feature lines from the surface but you don’t want to remove and redefine all of the breaklines.  Perhaps you also want to retain the feature line in your drawing and for some reason you would like to avoid using wblocks or the Windows Clipboard since this is not an Autodesk Best Practice for Civil 3D objects. This is no dilemma. Read more after the jump if you want to know a simple workaround to remove some of the feature lines from a multiple breakline surface definition while retaining them in your drawing.

Well here is the simple, quick workaround.  Select the feature lines you want to remove.  Copy the feature lines to a new site maintaining the original positions.  You now have two or more identical overlapping feature lines on different sites. Select both of them with a crossing window.  If you hold the SHIFT button and deselect the  feature lines on top, you are left with only the original feature lines selected (The last object created is always on top.)  Erase the feature lines and they are removed from the surface definition. You have the copy ready for editing and don’t forget to move the feature line back to the original site if needed.


  1. Neil Wilson says:

    The inability to graphically select and remove breaklines from surface definitions is a royal PITA, and the inability to change the tesselation parameters of featurelines after they have been added to a surface often requires having to go through that painful process.

    This workaround is certainly a worthwhile alternative to removing all breaklines and re-applying. Thanks for addressing this.

    Herein lies a great opportunity for a custom tool!

  2. John Mayo, PE says:

    Neil, did you post that wish to either the Augi or Autodesk Wishlists?

    And thanks!

    • Neil Willson says:


      Yes I have posted a wish to the Autocad C3D wish forum. I don’t use AUGI enough to post there. What I gather from the C3D user forums is that several others have complained about this, and I know Peter Funk has seen it in a particular discussion. Hopefully those who have a say in product development won’t consider it insignificant and will address it soon.

      I am finding that as technology enhances dynamic relationships it often brings data management issues which offset the gains in productivity.

  3. I’m still a big advocate of having all your featurelines on one layer, along with any 3D polylines or 2D polylines that you want to use as breaklines. Then, simply select that layer – using Quick Select – and add it as one Breaklines Set. Want to modify: simply make the adjustments on that layer and delete & re-add the entire Breakline Set. Modify \ create and repeat.

    • Neil Willson says:


      What is the reason for specifying tesselation parameters for feature lines? Is it not because in some cases we want tighter tesselation intervals and not others (i.e. on small curb return radii)? If we have applied varying parameters to featurelines when adding them to a surface, we lose all those settings when we remove everything and re-add them all at once.

  4. Mark Spatz says:

    I would not apply varying parameters. We don’t add that complexity into our designs and just use the same setting for all the featurelines we add to the surface. It works fine…

    Supplimental Distance –> 5′

    Mid-Ordinant –> 0.1′ (or 0.01′ – I can’t remember right now…)

  5. Neil Willson says:

    Well in our projects we typically model parking lots where 5′ curb radii are common. Those curbs need much tighter tesselation parameters vs. the 100′ plus radii on the streets. Thus we need a mix of settings. Otherwise performance is degraded if the same parameters are used throughout the project. All I’m saying is there is a need for improvement in the paradigm.

    I would like to see the tesselation parameters as a property of featurelines. That way they could be individually tweaked parametrically as needed without having to remove and re-add them to the surface.

    However that would not negate the need to be able to graphically select breaklines/featurelines in a surface as there would be other ocassions where that would come into play.

  6. Mark Spatz says:

    I don’t disagree, but until then would two layers work.

  7. Neil Willson says:

    Yes there are workarounds such as have been suggested in this thread. As I mentioned earlier, I feel the current paradigm is inefficient. A few simple enhancements would reduce data management overhead and improve productivity.

    It should not be necessary to remove featurelines from a surface just to change the tesselation parameters, and when there is a need to remove breaklines, there should be a way to select them graphically.