How to draw a 3d pline at a designed grade on a surface

[Anonymous]

Hi to everyone,

Is there a way to draw a 3d pline at a designed grade on a surface, using a feature line or something else?

I have found at http://www.dotsoft.com/mapworks.htm the tool named "GRADE POLY", but I would like to check if Civil 3d has something like that.

Thanks for any reply!

[Joe-Bouza]

Draw the feature line and set the grade with the elevation editor tool

[Anonymous]

The problem is that I want the feature line to be on the surface and with a specific grade starting from a 

specific point.

[Jeff_M · Accepted solution]

Dotsoft's tool is the only one I'm aware of. Nothing like this is built in to C3D.

[gknobbe]

you can use the draw feature line and this will give you all the options that you want, pick point, slope, grade, elevation, elevation from surface

from the command line

Specify start point:
Specify elevation or [Surface] <0.00>: 1200

Specify the next point or [Arc]:
Specify grade or [SLope/Elevation/Difference/SUrface/Transition] <0.00>: -2

Specify the next point or [Arc/Length/Undo]:

[wfberry]

Knobby:

Pick a point on a mountain side and give it a 3% slope and it draws an alignment down the the mountain on the surface.

Apparently this is what the OP wants.

Bill

[Joe-Bouza]

I dont see that as a problem; place the feature line on the surface extract the elevation and set the grade

[Anonymous]

wfberry you are right.

This is what I want to do and I beliave that only Dotsoft's tool can do it (see attached image).

Thanks all for your interest!

Pantelis Kouskoutis

[TerryDotson]

"I don't see that as a problem; place the feature line on the surface extract the elevation and set the grade"

The problem is that the coordinates of the next vertex are not known.  Consider the picture below.

The user knows the starting point (bottom of the map) and the acceptable slope (in this case -10% downhill).  From the starting point there are two solutions, one to the left and one to the right (as shown).  The routine follows the surface and generates the results which would lay on the surface as if you walked downhill and laid string along the path.  The routine stops when it can't continue on the designated slope.

I have attached the contours as a drawing so you can try your technique.

[Joe-Bouza]

OP said<Is there a way to draw a 3d pline at a designed grade on a surface, using a feature line or something else?>

Thats a great routine Terry! Do you have one help decipher what the OP is asking?  Evidently I'm the only one that didn't get it? How'd you all understand that the question was to generate a switch back path,  from the question?

[neilyj666]

I was also confused as to the OP's request - but the Grade Poly routine looks good

[Jeff_M]

Joe, the key for me was "designed grade ON a surface"...and, I recalled seeing similar questions in the past, one of which (I believe) was the motivation for Terry writing his routine.

[Joe-Bouza]

Thanks Jeff. I would have understood "find" a path on a surface to satisfy a design grade, but like the old slogan says "Reading is FUNdementl".

[Anonymous]

Guys thanks a lot for your replies and sorry for the tricky question. I didn’t know any other way to write it down. I have started to work with dotsoft mapworks addon, because civil 3d doesn’t have the capability to do something like that.

Thanks again!