A railway like no other

Source: CCTV.com

06-29-2006 11:06

The world's highest railway is a testament to human ingenuity. The project has encountered many problems, among them, high altitude, a fragile ecology, and thin oxygen. Qi Jie tells us how scientists tackled one of the most difficult engineering problems -- permafrost.

At four thousand meters above sea level, almost half of the 11-hundred kilometer line runs over permafrost.

The frozen ground is so sensitive that expands and contracts as the weather changes.

Engineers faced a double challenge--building a rail line with minimal damage to the environment.

Zhang Luxin said, "It's definitely a very challenging engineering problem. The key point is to cool the ground under the tracks so it doesn't absorb the heat from the train."

Heat conductors, ventilation ditches and thermal insulating ground make a safe journey possible. The train runs 100 kilometers per hour, a record speed in the permafrost zone.

In other places, the solution is bridges. The Qingshui River Bridge is more than one hundred kilometers long, running over the uninhabited Hohxil zone.

Although these solutions have proven workable, experts warn they aren't perfect. Zhang Luxin said, "We've already set up monitoring systems to observe the possible changes in the permafrost during the long-term operation of the railway. The system is designed to provide early warning when something unusual occurs."

There are nearly eighty monitoring checkpoints along the 500-kilometer permafrost section. The automated sentinels stand guard to ensure a safe journey.

Editor:Chen Minji