Project introduction: The ridge where the tunnel crosses is at an elevation of 4,017 m for its top, while the tunnel entrance is at 3,792.75 m. The tunnel, 1,530m long, is located in the alpine monsoon climate zone, with large temperature difference between day and night, damp and cold climate, short summer and long cold winter, average annual temperature of -3.4℃, the average temperature in January of -15.2℃, 7℃ in July, the average maximum temperature of 15.8℃, annual mean minimum temperature of -25.6℃, extremely maximum temperature of 22.5℃, extreme minimum temperature of -34℃; winter period is up to 228 days, the maximum frozen depth reaches 3 ~ 4.56m, the maximum snow depth of 200cm, the maximum wind speed up to 20m/h, the elevation of 3792.75m. The tunnel passes through the critical line of permafrost and seasonal permafrost, suffering from complicated engineering geological conditions and very bad operation environment. It is a tunnel in high altitude extremely cold areas with typical significance.

The project was completed in 1999. Because of limited materials and technologies at that time, disease problems take place in the project in different degree after the operation. The operating units began to use FLOLIC FOAM Freezing-thawing Resistant System for Tunnels in Extremely Cold Areas for optimization in 2007. Currently the tunnel runs in good condition; FLOLIC FOAM insulating thickness: 50 mm.