How to create a line 1m down from crest of slope

[Kimiko]

My project is on one side of a railway embankment, I have created a triangle surface using available data.
There is a line which marks the crest of slope.
I need to mark 1m vertically down from that line, but I'm not sure about the process to do so.

I have never draped a line before, but it sounds like the tool I need. However, the direction I want to drape is not on the Z plane.

Is this even possible?

I imagined a work flow would be...
Move crest line away in front of slope.
Lower crest line down Z axis by 1m
Drape (push) line back against slope to indicate a "contour" representing 1m vertical difference from crest.

Is this even possible?
Am I thinking of the correct process?

Any help would be appreciated.
Many thanks

[Lars]

Try this.

• Move (or copy) your embankment edge (3D polyline down 1 m, using AutoCAD's move command. From(0,0,0) to (0,0,-1)). This edge will be used as a reference line
• Use CadTools "Surface, Create Longitudinal Features"
• Load your surface, set Foreslope to -50, set Distance to zero, set backslope to zero, set Ditch Width to zero. Since your reference line should be lower than the surface you don't need to change the Fill slope value.

You should disable "Tick Marks" (Slope direction markings)

This will make CadTools follow your 3D polyline and create a perpendicular line on the embankment surface. Like using a horisontal laser beam.
Beware of "Side of reference line" setting. The accuracy of the resulting line depends on the reference line and the intervall setting (And your surface)

/Lars