Left 4 Dead/The Construction Site

You're in a storage area, currently a safehouse. Looters will be shot.

Route

 * Exit the safe house, head left.
 * You enter a construction area. Take the ground route, but a height advantage won't hurt.
 * Destroy the barricate with the nearby gas tanks.
 * The fire from the tanks causes something on the generator to flare into the air, attracting the horde.
 * Head down the opened alley.
 * Enter the high-voltage tansformer area, head straight through. You need not pass through other transformers if you don't feel comfortable in those areas; the grassy area nearby is fine.
 * After the second transformer section but before the third, turn right and right into the building.
 * Take a left, and right. Continue down path until you get outside.
 * The entrance is on the same side of the road you emerged from, but you have to go around an obstacle (wing of a crashed plane.) Enter it to get into a garage
 * Watch for a car-alarm en-route.
 * The garage leads to the skybridge - get to the second floor, and enter the bridge to reach the safehouse.