Is there a way to automatically create a Breakline from Exisitng Surfaces?

[nmessina]

Our company, was contracted to create a DTM of a residential neighborhood using our Lieca HDS C10 Laser Scanner.  Utilizing the Leica software I was provided LandXML file that contained a 2ft by 2ft Mesh surface along with breaklines for the edge of roadway, driveways and sidewalks, which was imported into Civil 3D 2012.   

Our client now wishes for us to provide them with a breakline for the crown of the roadway.  My first thoughts on calculating such breakline was to set the Contours at an interval of 0.05' to identify the crown of the road, then drawn the break line along the crown based on contours. 

Is there a way to automatically create a Breakline from Exisitng Surfaces? 

[JonRusk]

You could draw a polyline. Then create a feature line from object (on home tab). Check 'assign elevations' then on the next pop-up select your surface and make sure 'insert intermediate grade points' is checked.

[_Hathaway]

If you client wants a breakline at the crown simply create a polyline through the appropriate centerline points and then create feature line from objects as the reply above indicates.

If you don't have actual cl crown shots (points) you're creating an inaccurate breakline in my opinion.

[nmessina]

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@JonRusk wrote:

You could draw a polyline. Then create a feature line from object (on home tab). Check 'assign elevations' then on the next pop-up select your surface and make sure 'insert intermediate grade points' is checked.

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So far, I have created a polyline at the approximate breakline crown based on the contours.  Then from there I added verticies every 20 foot along the polyline.  I then created cross sections every 20 foot along the alignment. From there I am able to project and calculate and the crown location and elevation, see attached.  My plan was to adjust the crown location by adjusting the alignment vertices based on the offest distance to the apparent crown, then adjust the elevation of the profile based on the calculated elevation.

[david.zavislan]

Use the Catchment Area command to generate 3D Polyline boundaries.  The boundaries should delineate the crowns of the road.  Edit and trim the 3D polylines to isolate the crown breaklines.

[AllenJessup]

While you're doing well figuring a way to create the breakline in Civil 3D. Wouldn't it be better to create the breakline in the Scanner software and then bring it in to C3D. I don't have any experience with scanners but you were able to create edge of road breaklines there. So hopefully you could do it with the crown.

Allen

[Joe-Bouza]

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@_Hathaway wrote:

If you client wants a breakline at the crown simply create a polyline through the appropriate centerline points and then create feature line from objects as the reply above indicates.

If you don't have actual cl crown shots (points) you're creating an inaccurate breakline in my opinion.

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I'm thinking if he wanted it maybe he should have paid for it. I think that goes hand and hand with the accuracy issue you bring up, Mike