Left 4 Dead/The Terminal

You've just entered the airport.

Route

 * Exit the safe house to the main terminal area.
 * Go through the main office hallway.
 * Exit the offices, and head down to the lower floor.
 * Start the van have it move fowward to knock down a barricate
 * It's holding some portion of the building up; when it collapses, the horde gets alerted.
 * In the newly opened area, advance, and go through the baggage area. Enter the conveyor belt.
 * Go straight ahead to the end of the coorridor. You'll reach an atrium.
 * Cross the atrium, up the stairs.
 * Don't set off the metal detectors, unless you're a smoker pulling a survivor through them.
 * On the second floor, hug the right glass windows to reach the final safehouse.