Note: this glitch has not been confirmed - please comment below to confirm.

In TranZit when you reach the lab (the place after the farm) open the door which is a shed door. Don't turn the power on or the glitch won't work!

OK, you have to keep your turbine (and if you don't know how to make them look at the cheat section below) so you can open the door near where the working table is (to the left).

Open the door with your turbine, go up the stairs and jump across the gap at the top of the stairs.

Here is where you do the glitch (remember what I said - DON'T turn the power on).

Crouch when you get across, then turn around and don't jump back over. Instead slowly walk over the gap then you will be floating in thin air.

The zombies can hit you, but this is very rare.