Creating 3D solid model of underground vaults from wireframe linework

[mmccarter]

I have a client who for whom we have carried out a survey of a large area and they now require an AutoCAD 3d solid model of the whole site.
The current drawing consists of wireframes of underground vaults which sit adjacent to a road/railway and below a wasteland area. We have the above ground topographic survey as a 3d AutoCAD linework survey which we will create a surface of in Civil3d (not sure how this will export) or from 3d contours created in civil3d or our survey processing software "n4ce" which I will loft.

The most obvious thing about this job is that AutoCAD is not the ideal software for the task, but due to the many problems which always appear when exporting from Max or Rhino we have to do most of the work actually in AutoCAD.

The end product (if it's achievable!) will look very understated for the amount of work involved in creating it due to most of the intricate detail being hidden away inside the "ground" with vaulted ceilings etc in it, none of which will be visible!

Where this will come into it's own is that the client will be able to cut sections in it where ever they want to or do volume calcualtions.


The problem I am encountering is in creating the cutting objects for the vaults which will be used subtract from the main solid.
The ground of each room is uneven, meaning that I can not easily create a surface for it. I can create a mesh using edgesurf, but this mesh can not be used to form part of a solid (or so I believe). One work around I have tried which works is to explode the mesh into 3dfaces and then create a solid from them using "f2s.lsp" which I found. The trouble with this is that the number of 3d faces is going to end up being massive and the file size too large.
I have also created the surface in Rhino but it rounds off the corners and it does not quite match our original linework.

I also need to create a surface for the vaulted ceiling using the existing linework. The arcs at each end of the ceiling are NOT the same, and the opposite walls at the bottom of each arc are not always parallel. Trying to use the two end profiles to create the surface suing the lfot command returns an error messege, so another method must be found. Is there a way in AutoCAD to do this I am unaware of? Rhino seems to work well for this type of surface and they import into AutoCAD as a surface in ACIS format.

Once I have solved these main issues I feel I should be able to do the rest eventually! Although any suggestions or input is very greatly recieved. I'm hoping that someone like jaberwok can help out here.

I have included an extract .dwg of some of the date and highlighted what I believe to be the most difficult room to model and also a .pdf of the whole site in an isometric view.