Topic: A line following existing ground at a set grade

[surveyor_randy]

I've got an unusual question, a co-worked came to me today and asked me if there was a way to draw a line on an existing surface that will follow that surface at a 2% grade.  At first I thought about using a feature line, but I couldn't see a way to do this.  He is basically wanting a line drawn on the existing surface that snakes along that surface at a 2% grade avoiding any cutting or filling.  He would like to click on a start point (grab the elevation from the surface) then click on an end point (grab the elevation from the surface) then generate a line following existing ground at 2% between those two points.  The shape of the line doesn't matter.  I told him I would ask around and see if it can be done.  I could write a routine in VB.net to do this but if C3D has the ability already integrated, I wouldn't mind learning how to do this either.

Has anyone else ever had to do this, and how did you accomplish this?  Thanks all!

[mjfarrell]

Strike that......

This would suggest that one create an alignment and a profile along that alignment from the EG Surface.
Turn on a Profile Label Set that shows the tangent slopes, and then modify the alignment, such that it follows EG +/- 2%

Or one could set up a slope analysis to show where those slopes where and draw the alignment there.
OR set up the surface style to display the TIN Face slopes and use those as your guide.

[surveyor_randy]

Thanks for the suggestions Michael.  I looked into the TIN face slopes solution and I didn't see in 2008 where you could label TIN face slopes.  And it seems like drawing an alignment and then adjusting the alignment based on the profile would take almost as long as doing it by manual calculations.  I will pass your suggestions on to him and let him decide what he wants to do.  In the mean time, I am going to work on a .NET solution unless anyone else has an easier suggestion.
Thanks again!

[mjfarrell]

Thanks for the suggestions Michael.  I looked into the TIN face slopes solution and I didn't see in 2008 where you could label TIN face slopes.  And it seems like drawing an alignment and then adjusting the alignment based on the profile would take almost as long as doing it by manual calculations.  I will pass your suggestions on to him and let him decide what he wants to do.  In the mean time, I am going to work on a .NET solution unless anyone else has an easier suggestion.
Thanks again!

Go create a Surface Style.

Turn on Slopes, and slope arrows

Then perform an analysis, setting the slope range colors to something meaningful.
then do the analysis on the surface, and the desired slope ranges will lite up a Cool color, and the undesirable sloped areas will light up a HOT color and it should be pretty easy to draw the trial alignment where the slopes are favorable. There will be some modification required around curves and such. I see the interactive profile method being the easiest and fastest even without the slope ranges shown on the terrain model, just by using the contours as a guide.


send me some data, and let me peek at it for you

[mjfarrell]

Randy,  I think you have sort of identified a partial rule set to get this alignment whereever it needs to be within your slope limits, of -2%/2%. As at times it will need traverse or follow grade to stay within your limits.  At least from what I am reading of the design challenge.

No?

[John Mayo]

http://discussion.autodesk.com/thread.jspa?messageID=5873024

Check with Terry at www.dotsoft.com. I think he did get some code together to do this.

I think someone may have also posted the code on the Autodesk NG. Look into the above post & you may find it.