The tunnel is one of six 10km tunnels being constructed on the most difficult part of the 160km/h line. Milin tunnel is about 1200m below the surface and has an average altitude of 3100m.

The Lhasa - Nyingchi section of the Sichuan-Tibet Railway will be the first electrified railway in Tibet. It is located in the southeast of the Qinghai-Tibet Plateau, one of the regions with the strongest movement of the earth’s crust in China. Workers face altitude sickness, bad weather and a difficult environment.

“The successful penetration of the tunnel has formed a new experience in the construction of railway tunnels under extremely harsh natural conditions,” says China National Railway (CR). “It will provide a very useful reference for the Yaan - Linzhi section of the Sichuan-Tibet railway, under planning, in terms of technological research and development capabilities and engineering construction practices.”

CR says experience gained during the construction of the line has increased scientific and technological research, and produced innovative techniques to overcome aeolian sand, toxic and harmful gases, high ground stress, high ground temperatures and moraine layers. Tunnel construction challenges have been overcome and several new techniques applied such as wind and sand fixation, comprehensive cooling, water and mud inrush prevention and control, and rock burst control, resulting in 32 patents.

So far, 47 tunnels and 120 bridges have been built, and track laying has been completed on 115.11km of the line. CR expects to complete the line by the end of 2020 ahead of opening in 2021. 

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