Site modifiers and Cut and Fill calculations

[Christine Mulinder]

I'm a bit confused by some calculations for cut and fill that Vectorworks is giving me - this could of course be my own ignorance on the subject!

 

In the attached going from the bottom up, the first site model slopes steeply and I want to level it out. The second is the site model with a spoil pile modifier at elevation 480 on the left of the model and it gives me a cut volume of 0 and fill volume of 28.03m3. In the 3rd image, I've used a pad modifier over the whole site at an elevation of 480 and it gives a cut volume of 13.477m3 and fill of 12.582m3 with .895m3 left over (26.954 m3 total). The top image is the 2d model. Why the discrepancy? Which modifier should I be using to work out how much to spread and how much to remove as this has obvious cost implications and I want to get it right.

Site Models.pdf

[Tom W.]

It sounds to be like you're virtually there with the 3rd image if it results in only 0.895m3 of soil needing removing from site. As far as I understand, the Spoil Pile Modifier is what you'd now use to get rid of that 0.895m3 by spreading it somewhere on the site to lose it. That is why in your 2nd image you have ended up with a fill value of 28.03m3 + a cut value of zero: because in effect, using a spoil pile you've just come along + spread a load of soil over the site.

 

Alternatively can you raise the elevation of your pad modifier slightly to reduce the 0.895m3 you currently need to remove from site? Raise it incrementally until there's zero left over?

[Christine Mulinder]

Thanks Tom, that makes sense