Thanks for the responses. They are helpful. We already 3D laser scanned (point clouds) piping inside our tunnels, georeferenced this data to the coordinate system we use in our GIS. Leica Truview software (the free viewer) we can view our 3D piping data in all its wonderful glory, amazing stuff. We then click on the particular pipe to get its xyz coordinates, export these coordinates into an xml file. Then we open this xml file in Excel, save it as a spreadsheet, then import this spreadsheet into our ArcGIS Geodatabase. We then create a point feature class with the xy coordinates. From the points we then create a polyline in our Pipes Feature Class and attribute the pipe accordingly.
This has many advantages for us:
1) We spend less time manually mapping pipes while physically inside our tunnels lugging around a pen and paper clipboard or heavy tablet craning and turning our necks 360 degrees. Now this is done directly from the comfort our desktops.
2) We have XYZ attributes for our tunnel piping.
3) Even though we are using this data in ArcGIS as 2D, not 3D, we are 3D "ready" in the event ESRI develops a 3D Piping solution, and we know the height and length of the pipes in our tunnels useful for construction purposes.