The world's highest railway, Qinghai Tibet Railway extends 1,956 kilometers from Xining, capital of Qinghai Province, to Lhasa. Nearly half of the Qinghai-Tibet Railway lies more than 4,000 meters above sea level and about 550 kilometers of this railway is laid on frozen earth. Its highest point is as high as 5,072 meters. The highest station on the line is Tanggula Station (5068 meters above sea level) which is also the highest station in the world. In addition, the Qinghai-Tibet railroad runs through the world's most elevated tunnel, Fenghuoshan Tunnel (4,905 meters above sea level) built on frozen earth and the world's longest plateau tunnel, Kunlun Mountain Tunnel (1,686 meters long) built on frozen earth, too.
Construction of this railway was divided into two phases. The section from Xining to Gomuld was finished in 1979, while the section between Gomuld and Lhasa was finished in 2006 after 5 years' arduous construction. It was opened to traffic on July 1, 2006. The first three trains running on this highest railroad are trains from Beijing-Lhasa, Chengdu-Lhasa and Xining-Lhasa. The train is designed to operate at a speed of 100 kilometers per hour on the frozen earth and 120 kilometers per hour on non-frozen earth.
The Qinghai-Tibet Railway records the great efforts and strong perseverance of the engineers and workers put in overcoming difficulties during construction. This railway is at such a high altitude and in such a mountain area, they encountered three world challenges- permafrost, fragile ecosystem and lack of oxygen. However, they still found ways to solve these problems.