Left 4 Dead/The Subway

From the safehouse, you need to travel in the subway tunnels to cross a portion of the city. The next safe house between you and mercy hospital is a pawn shop.

Paths
Most of the travel on this map before the generator room - aside from the initial subway platform, there is only one route available, and the minor branch only determines which side you use to enter the railway.

After clearing the generator room, you can either try jumping out the window (if you have enough health and can survive the fall), or walking downstairs.

Traps

 * After leaving the subway, you enter a generator room - priming the generators to open the door will cause the horde to become aware of your presence. However, a turret will cover most of the room (but doesn't cover a hole in the back of the room.)