Designed by China Railway Eryuan Engineering Group and examined by China Railway Academy, the Xiang Ngeun No.3 Tunnel of the Boten-Vientiane section of China-Laos Railway was completed on September 28, marking that all of the 75 tunnels along the China-Laos Railway have been completed.

Measuring 2,633 meters in length, the Xiang Ngeun No.3 Tunnel is located in Xiang Ngeun County of Luang Prabang, Laos. The geological structure and hydrological conditions for the project are extremely complex. The engineering team had to tackle many problems including faults, dense fractured sections, well-developed fissure water, and the surrounding rock tending to soften when meeting water. The smallest depth of the tunnel is 16 meters, making construction even more difficult. Since the construction of the China-Laos Railway began at the end of 2016, the engineering team of the Southwest Institute of China Railway Academy has carried out inspections and geological predictions on more than 30 tunnels on the Moten-Vientiane Railway. (By Sun Qiang, Yang Yibo, China Railway Eryuan Engineering Group)