Toposurface Void for Underground Garage


I am trying to create an underground parking garage with tunnels connected and a green roof above. I’ve tried several opintions but want to keep the existing toposurface untouched and just have a dynamic void item cutting the topography so that 3D veiws and sections show correctly.

I first tried to create a building pad but this has limited functionality. (No sloping, top or height control). I then tried extracting the surface to DWG and modelling a roof based on that but appears far too cut, tessellated and inaccurate.

Can I use Dynamo to create a more functional void or simmilar item that will cut topography? So Far i can only extract the point data of my topo.

@JDGregg See if this helps…
TopoTunnel.rvt (1.1 MB)

Elaborating on a suggestion provided here
topoSolidTunnel.dyn (11.9 KB)