I have been given a bunch of underground tunnel outlines as 2D polylines and a recent survey that lists 3D survey points at regular intervals down these tunnels. I need to recreate 3D tunnel outlines from the 2D outlines and the 3D survey points.

Can anyone suggest an efficient way to achieve this goal.

thanks
Alistair

Thanks Vladimir. 2D>3D lisp routine works great. thanks. It's a good first step. Basically I have 2D linework that represents 3D tunnel outlines. These lines show the walls of the tunnels in great detail, digitized from old paper maps. All the lines are at 0m elevation. I want to maintain the detail of the tunnel walls in x and y, but add a z value to each point derived from the new 3D survey of the tunnel floor so that the tunnels are in correct 3D space. Any further suggestions would be much appreciated. 

Thanks Carl. I had considered generating the 3D points in excel, but it seemed a lot of work and I was hoping for a push button solution (ha). I did try a solution by connecting the survey points with a 3D poly, dividing this 3D poly using a simple line as a block, oriented perpendicular poly, then redigitizing the tunnel outline by snapping to the apparent intersection of these closely spaced blocks with the existing 2D polyline. It too is a lot of work and results in a degradation of the original x,y data. I'll try out the excel method as well to see if that turns out faster or better.