Not able to extrude topographic lines

I’m trying to extrude these topographic lines, but it’s not working. I used boolean curve but lost the topographic lines. Does anyone know how to resolve this problem.

site map.3dm (15.0 MB)

Hi Dan -

From the image and the file, I’m not sure what you are trying to do.
That said…

If that is the CurveBoolean command, depending on the settings, the input curves will be deleted.
-wim

I’m trying to convert the roads on the terrain into surfaces, but I can’t because they’re not planar surfaces.

Hi Dan -

You have a lot of extra curves and overlapping curves that are on the “3D Roads” layer, but if you clean that up, you can split the mesh with the curves, and then extrude the road meshes.
-wim