Importing survey from DWG

[cls]

I need to make a site model and have an old survey supplied as a DWG. On import the survey is 3D polys which I have converted to 2D polys and I am using the combine connect tool to remove line breaks. The problem is, every 2nd or 3rd line it will either not connect, cause one side to disappear, cause the contour line to change to an odd shape, or crash Vectorworks.

Any tips on how to import survey data from a DWG and use it to create a site model?

[CipesDesign]

Here is my basic process: first import the dwg into a new clean VWs file. Remember to add a prefix to all the imported classes (which are actually auto cad layers). That way the resulting class list will be easier to manage later on. After importing double check that the data scales accurately.

Find the classes which contain the contours. Make all other classes invisible. Check each and every contour for continuity. Fix any that are not one single poly either by selecting segments and using the Compose command, or if necessary, dragging or adding vertices to ensure EXACT end point to end point connection(s) and then running the Compose command again.

Side note1) almost all files will have some or perhaps many polys in need of repair. Because most people are sloppy...

Side note 2) many or most newer survey files will already contain a site model (or a triangulated terrain map), so it pays to do a thorough examination before doing any of the above... Older files, as you describe, will require more work.

From here there are two ways to proceed. 1) select all of the polys and run command 2d Polys to 3d Contours. Now be alert, because this command/ routine uses the order of creation (of the polys) as the order of the sequence for each successive contour, so things can get wacky. One way around this is to sequencially Cut, then Paste in Place each poly, starting with the lowest elevation and proceeding upward in order, then run the command, or

2) sometimes depending on the number of polys involved, I find it easier to Select all the polys and use the Convert to 3d Poly's command. This results in a group of 3d polys which all have zero in the Z field. So I actually type in the Z value for each one.

Once you have all the 3d polys set to their proper Z heights, just Select them all and run Create Site model. Voila!