Friday, April 7, 2017

Calculating Site Cut and Fill Volumes with Revit and Dynamo

From the Revit Dynamite and Ammo blog:

Ammo: Excavations with Revit and Dynamo

So to the subject of the day: Revit and topographical volumes is no good, right? Well, I can tend to agree on that point.

Sure Revit does calculate net fill/cut etc etc, sure you have possibilities in Site Designer and other addins and sure - you really should use Civil 3D.. Right tool for the right job and so on.

If you however are as me you will need from time to time to accomodate these things in Revit.

A typical workflow we find ourselves in as a structural engineer on small to medium sized projects is that the contractor or our customer wants us to produce an excavation plan something along the lines of this:

Now this is quite often manual labour and we really want to accomodate this in a much better manner.

I've spent some time investegating the possibilities in Dynamo regarding creating solids of these volumes. What we want is a more efficient way to produce the drawings and in addition we want to extract the total volume excavated.

Now why haven't we been able to do this? The reason is sloped excavations. How do we create a solid that are "correct" when presented on a drawing or that calculate the volume we want it? It really has to do with how the internal offsetting of curves are done in Dynamo. You see the offsetting in Dynamo is not that good, unfortunately, but recently I found a little and hidden package called DynamoClipper. See here for a little comparison on how the two methods for offsetting works differently:

Now, suddenly, it works the way we expect it to, so here is a little example:

The Revit model (before any scriptrunning)

The script:

Part 1:

Part 2:

Part 3:

Running the script:

And of course, the results:

A solid with correct levels, slopes, corner cuts. All ready to place spot elevations, do dimensions etc.
Not all together finished, but we've gotten a long way.

Packages needed:
  • Clockwork
  • Springs
  • DynamoClipper

Revit test file:

Dynamo script:

There's more information available on the Revit Dynamite and Ammo blog.

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