The best way to test out the feasibility of the route is to go out and give it a try - to stress test it.
The first such full trial run was performed on April 1st 2011 (no joke!). In short, I spent 17 hours on the underground system, and failed to get to my destination. Fail.
Still, I was probably in a better state at the end of it than these two guys:
Project Plan >