Two years ago, we covered the story of a group of engineers and construction workers involved in a nearly impossible endeavor. Their attempts to carve a single railway tunnel through one small mountain in Yunnan had, according to the project foreman, "tortured me for nine years". By finally solving longstanding ventilation and drainage challenges, the tunnel now has a clear completion date, something it has lacked for more than a decade.
The Dazhushan Tunnel system lies beneath a stretch of the Hengduan Mountain Range about 20 kilometers north of the city of Baoshan (保山). Workers there have been toiling to finish a 14.5-kilometer series of passageways through bedrock since the opening ceremonies of the 2008 Beijing Olympics. A combination of impenetrable geological formations, underground rivers and minor fault lines all conspired against much progress.
The most challenging of these obstacles were a constant inundation of water coupled with extreme temperatures. The construction crew labored in ambient temperatures regularly above 40 degrees centigrade and suffered through constant relative humidity of 85 percent for three years, according to official news accounts.
The "breakthrough" announced June 26, involves the installation of proper and permanent ventilation, alongside a complex water drainage system able to deal with up to 78,000 cubic meters of water per day. Additionally, "micro-faults" in the surrounding rock have been sealed with chemicals. With such improvements, the construction crew will no longer have to don raincoats underground or require five tons of ice each day to help keep them cool.
The Chinese press has dubbed this stretch of tunnel "the world's most difficult", and for those who have spent the past 11 years building it, the moniker is apt. Official estimates now say the dedicated men and women struggling to finish the underground passageway will finally be done as of late 2020. But this Herculean task is only one part of a much larger undertaking — the Dali-Ruili Railway (大瑞高铁).
Once finished, the line will connect central Yunnan to the border with Myanmar, and maybe one day to railway systems in Bangladesh and India. Following the June 26 announcement of tamed water, officials are hopeful the Dali-Baoshan portion of the railway we be in service by December 2020, and that the entire railway from Dali (大理) to Ruili (瑞丽) will go into operation before the end of 2022. Patience is a virtue.
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