One Way Passage (23)

Watch out for a gigantic boulder being flung on the river. Shoot it and avoid it as much as possible, treating it like a Car (a common infected type).

When the Tank (a special infected type) has been slain, go up the scaffolding leading towards where the Tank came from.

Grab any available Packs (items) and Guns (weapons) if necessary, and follow the road.

Keep going until you reach a blocked road with vehicles like a bus and a truck planted sideways.

Go back to the creek on the left. A humvee (vehicle) here may contain something special.

Follow the creek until you reach a crashed helicopter. Avoid the fires, as it's possible to get trapped.

Go up the steps back onto the road.

Find the Chainsaw (weapon) in the small truck.

Avoid the Alarm Car (a vehicle that attracts common infected).

Hop onto the pickup truck, then onto the bus. This is the way to get over the fence ahead.