Megastructures: Extreme Railway

This is the story of the struggle to build a railway across one of the most extreme environments on Earth... to lay down over a thousand kilometers of track in a remote wilderness... to drive seven tunnels and raise 675 bridges, at an altitude of nearly 5,000 meters, where breathing is an arduous task. 140,000 workers and 2,000 medics worked for 5 years to conquer this hostile environment in order to complete the Qinghai-Tibet railway, the highest, most extreme railway in the world! (ZDF)