The Dalong No. 2 tunnel of the China-Laos Railway, being built by Sinohydro Bureau 3 Co, a subsidiary of POWERCHINA, was recently drilled through. This is the third tunnel to complete drilling during the COVID-19 pandemic. The tunnel, located in the Luang Prabang Province in Laos, has a design speed of 160 kilometers per hour and is 2,321 meters long. Officials said the tunnel area is a structurally eroded alpine landform with large terrain relief and a relative height difference of more than 100 meters. The lithology is mainly carboniferous slate with sandstone, marlstone and limestone slate, which developed joint … Read more