Greg,
I wrote this quite a while ago but I think it will still work.
• After the topo mesh is complete with all the ridges at there correct
elevations, rename it "topo proposed" in the ID field
and draw the outline of the roadway with the polyline tool in the correct
position on the mesh.
• Edit the contours so they are correct for a road. This could involve
considerable editing to make the the transverse cross-section of the road
level and the grade of the roadway even and at the correct slope.
• Select the mesh and the polyline and drag a copy a known distance away
from the original. This new mesh is going to be the roadway mesh with
every thing else removed.
• With the mesh tool selected, click on the edge of the mesh, the pet
palette comes up, select the MINUS button and trace a closed polygon
around all areas of the mesh that are not part of the roadway.
Where the roadway ends at the edge of the mesh continue the selection
line outside the mesh around to the point where the roadway meets the
edge of the mesh again,when the selection line comes back to where it
started that portion of the mesh that is within the selection polygon will
be removed.
• When all that remains of the mesh is the roadway select the mesh and
assign it an appropriate material and pen color and rename it "road
proposed" to distinguish it from the "topo proposed" mesh.
• Drag the roadway poly line back to it's original position on the
"topo proposed" mesh. Using the same MINUS button method trace
completely around the roadway, when the selection line comes back to
it's starting point the roadway area is removed. Delete the polyline and
drag the "road proposed" mesh into position in the "topo proposed"
mesh.
Peter Devlin
