KUNMING, July 9 (Xinhua) -- Chinese workers on Thursday dug through a high-risk tunnel that runs through rock layers containing a variety of noxious gases.
The Hongdoushan Tunnel in southwest China's Yunnan Province is part of a railway project linking the cities of Dali and Lincang. Its construction began in May 2016.
About 73 percent of the 10.6-km tunnel went through highly dangerous areas that contain eight harmful gases, including hydrogen sulfide and carbon dioxide, according to the tunnel's constructor China Railway No.10 Engineering Group Co., Ltd.
The company said it is the first time that a Chinese tunnel project has encountered harmful gases of so many categories, and in such a high concentration.
Quan Fei, deputy chief engineer of the project, said workers had to wear gas masks while enduring temperatures up to 40 degrees Celsius in the four-year construction period.
With a designed speed of 160 km per hour, the 202-km Dali-Lincang electrified railway will be the first railway linking Lincang, whose operation is expected to boost China's connectivity with neighboring countries. Enditem
