Cut And Fill Areas

[ceaser]

I wonder if somebody can help me

Image a piece of virgin ground against the side of a mountain. Against this mountain we need to construct a road. Now, part of the road will be cut into the mountain and the other part will be filled up. This is looking at a cross-section of the road.

Now here is my problem If I take a cross-section anywhere along the road, part of it will be in a cut condition and part of it will be in a fill condition. I need a fast way to determine the cut area and the fill area at any specific section.

I have the levels and offsets relative to the centerline of the original ground and also the levels and offsets of the design at that cross-section.

What I have done is to project the ground offsets onto the design line and calculate the design levels at each ground offset and then projected the design offsets onto the ground line and calculated the ground levels at each design offset.

What I ended up was a whole lot of squares between the design line and the ground line. This way I could calculate the area between the design line and the ground line and also determine whether it was in a cut or fill condition. It is fine on the PC, but on a handheld it is a bit slow.

I have thought about using the area by coordinates formula "((X1*Y2)+(Y1*X2))-((X2*Y3)+(Y2*X3))...etc. But this does not tell me whether I am in a cut or fill condition.

Any ideas?

Thanks
Michael