Breathtaking scenery and breathtaking dangers -- both will face Chinese engineers as they embark on building the world's most difficult railway.

The Sichuan-Tibet Railway will be the second railway into southwest China's Tibet Autonomous Region after the Qinghai-Tibet Railway. The line will go through the southeast of the Qinghai-Tibet Plateau, one of the world's most geologically active areas.

The Sichuan-Tibet Railway will be a major line in the western China rail network, connecting Tibet and more developed central and eastern regions. The design speed is from 160 kilometers per hour to 200 kilometers per hour. On completion, the travel time by train from Chengdu to Lhasa will be cut from 48 hours to about 13 hours.