Driving on Yakang Expressway - One of the most difficult expressways to build in China - 4K
Yakang Expressway starts from Duiyan Town, Ya'an City in the east, passes through Tianquan County and Luding County, and ends at Lucheng Town, Kangding City in the west. Yakang Expressway connects to Chengya Expressway in the east, with a total length of about 135 kilometers; the Ya'an section is 89 kilometers, the Ganzi section is 46 kilometers, the roadbed width is 24.5 meters, the estimated total investment of the project is 23 billion yuan, the approved construction period is five years, and the altitude difference of the entire highway reaches 1,900 meters.
After the Yakang Expressway is put into operation, it will take nearly 4 hours to get from Chengdu to Kangding, which saves at least 2 hours compared to the original journey. At the same time, the bridge-tunnel ratio of the project is as high as 82%, which is one of the expressways with the highest bridge-tunnel ratio and the most difficult construction in the province and even the country.
The construction of Yakang Expressway faces a series of major technical and economic challenges such as safety, economy, ecology, and convenience. The Erlangshan super-long tunnel, a key project, is 13.4 kilometers long, ranking second among the highway tunnels under construction in China; the main bridge span of the Xingkang Bridge on the Dadu River in Luding is 1,100 meters, ranking first among similar bridge types in the province; the 50-kilometer-long tunnel group passes through high mountains and canyons, and the construction is extremely difficult. The bridge-tunnel ratio of this project is as high as 82%, making it one of the highways with the highest bridge-tunnel ratio and the most difficult construction in the province and even in the country. The altitude difference of the entire line reaches 1,900 meters.
The construction of the project is extremely difficult. The project repeatedly interfered with the G318 line and hydropower facilities, posing a high safety risk. The 50-kilometer-long tunnel group crossed the high mountain canyon, and the construction access roads were laid on the cliffs. In particular, the tunnel group in the Lu-Kang section had a vertical height difference of about 580 meters between the tunnel and the G318 line. Some contract sections needed to build about 8 kilometers of construction access roads on the steep slopes of the canyon to reach the tunnel branch tunnel operation point. In the absence of laying access roads, nearly 1,000 meters of tunnel branch tunnels were opened to reach the tunnel main line construction. The construction access roads needed to detour nearly 24 turns due to the line extension, making material transportation, tunnel slag disposal, and power supply extremely difficult. Several large construction units in the C16-C18 contract section located in Luding and Kangding took 1 and a half years to open up the construction access roads and construction branch tunnels, and finally started the main line tunnel construction in 2016. The Xingkang Bridge on the Dadu River has a span of 1,100 meters, the largest in the province. It faces extremely high earthquake intensity (eight degrees), complex wind field conditions, and extremely unstable steep slopes. The Erlangshan Extra-Long Tunnel is 13.4 kilometers long, with a maximum burial depth of 1,700 meters and high ground stress. It is prone to rock bursts and large deformations. It crosses 13 earthquake fault zones and has unfavorable geology such as gas, karst, and gushing water. The construction quality and safety risks are high. The single inclined shaft is 3.3 kilometers long, and the tunnel is excavated from the end for 6.8 kilometers. The scale of inclined shaft construction and tunnel excavation from the end are the largest in the country.
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