Rail Transport in Tibet - Engineering Challenges

Engineering Challenges

There are many technical difficulties for such a railway. About half of the second section was built on barely permanent permafrost. In the summer, the uppermost layer thaws, and the ground becomes muddy. The heat from the trains passing above is able to melt the permafrost even with a small change in temperature. The main engineering challenge, aside from oxygen shortages, is the weakness of the permafrost. Many of the engineering challenges therefore deal with the maintenance of the permafrost. For areas of permafrost that are not very fragile, an embankment of large rocks is sufficient. Meanwhile in the most fragile areas, the rail bed must be elevated like a bridge. Chinese engineers dealt with this problem in the areas of weakest permafrost by building elevated tracks with pile driven foundations sunk deep into the ground. Similar to the Trans-Alaska Pipeline System portions of the track are also passively cooled with ammonia based heat exchangers. Despite the government's best efforts, the integrity and strength of the railroad is not fully secure. Due to Climate change, temperatures in the Tibetan Plateau will increase by an estimated two to three degrees Celsius. This small change, although minute, is sufficient to melt the permafrost and thereby affect the integrity of the entire system. The effects of climate change have yet to be seen.

The air in Tibet is much thinner, with oxygen partial pressure being 35% to 40% below that at sea level. Special passenger carriages are used, and several oxygen factories were built along the railway. Each seat in the train is equipped with an oxygen supply outlet for any possible emergency. At this elevation in these latitudes, water in toilets must be heated to prevent freezing. The Chinese government claimed that no construction workers died during the construction due to altitude sickness related diseases. The railway passes the Kunlun Mountains, an earthquake zone. A magnitude 8.1 earthquake struck in 2001. Dozens of earthquake monitors have been installed along the railway.