AutoCAD Civil 3D General Discussion

AutoCAD Civil 3D General Discussion

Active Contributor
Posts: 26
Registered: ‎10-10-2012
Message 1 of 2 (805 Views)
Accepted Solution

How does Civil3D Calculate Average Slope?

805 Views, 1 Replies
02-20-2013 12:19 PM

Does anyone know what formula Civil3D uses to calculate the average slope of a surface?


The formula I am using is S = I*L/A


S = Average Slope

I = Contour Invertval

L = Length of Contours (ft)

A = Area of parcel (sq. ft)


I just had to do four parcel calcs and the percentage I find using the formula is always 1-3% lower than the percentage Civil3D spits out. I can't find anything about how Civil3D arrives at that number, it just appears. I assume that Civil3D is more accurate but I can't give that number to a client without knowing how the program arrived there. Any clues?

*Expert Elite*
Posts: 2,110
Registered: ‎11-08-2005
Message 2 of 2 (773 Views)

Re: How does Civil3D Calculate Average Slope?

02-20-2013 03:05 PM in reply to: dankoss

The software apparently uses a weighted average formula.  Check this thread for more info.

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