The Qinghai-Tibet Railway

In Geotimes:

China made history on July 1, 2006, when the Qinghai-Tibet Railway opened for passenger service. The railway is the highest-elevation passenger train in the world and the first to connect central China with Tibet, providing a controversial but arguably economically significant link between Tibet and the rest of China. Stretching about 1,142 kilometers, the railway runs from Golmud in China’s Qinghai province to Lhasa, Tibet’s capital. Most of its length is above 4,000 meters in elevation, and 50 kilometers is above 5,000 meters.

The railway traverses the spectacular topography of the Tibetan Plateau, cutting across four mountain chains — Kunlun, Fenghuo, Tanggula and Nianqintanggula — where elevations of the trackbed are all above 4,600 meters. It also crosses five major rivers — the Yellow, Yangtse, Mekong (Lancang), Nujiang and Lhasa-Brahmaputra — and passes through the Three Rivers National Natural Protection Region, an area known for its biological diversity, geological and landscape variety, and scenic beauty in southwestern China.

At 4,650 meters elevation on the Tibetan Plateau, with atmospheric pressure and oxygen 45 percent lower than at sea level, an annual average air temperature of 5 degrees below zero Celsius, and extremes including low temperatures of negative 47.8 degrees Celsius and wind speeds above 30 meters per second, this is a harsh climate. Add in solar and ultraviolet radiation 1.5 to 2.5 times what it is at sea level, and not only is preconstruction research and fieldwork a challenge, but so is the construction itself.