The reporter learned from Qinghai Provincial Transportation Construction Management Co., Ltd. that the left tube of the Gagou Tunnel, another tunnel project on the G227 Line Laochengguan-Xining-Shangxinzhuang Highway, was recently holed through, marking the full breakthrough of both tubes of the tunnel.

The G227 Line Laochengguan-Xining-Shangxinzhuang Highway starts at the Chengguan junction in the southeast of Chengguan Town, Datong Hui and Tu Autonomous County, and ends at Shanmatai Village, Shangxinzhuang Town, Huangzhong District, Xining City. It is an important new major corridor for north-south transit through Xining. The route passes through Chengguan Town junction, Qiaotou Town, Changning Town, the Biological Park, Haihu North Road, Haihu Road, Kunlun Road, Tongren Road intersection, Jianguo South Road, Jianzha Road, Xincheng South Road, Nanchuan Industrial Park, Chenjiantan Village, Shangxinzhuang Village, and Shanmatai Village. The route is 82.35 kilometers long in total and is designed as a Class I highway with two-way four lanes and a design speed of 60 kilometers per hour.

The Gagou Tunnel is a controlling project for the entire G227 project. Each tube is designed to Class I highway three-lane standards, making it a large-span tunnel. The right tube of the tunnel is 814 meters long and was holed through in August this year. Construction of the left and right tubes lasted 3 years and 6 months. During tunnel construction, the participating units encountered entry into the tunnel through landslide body areas, water inflow at the working face, crossing water-rich gravel layers, and shallow-buried mudstone sections; they overcame many construction difficulties and key points such as complex and rapidly changing surrounding rock, providing safety and technical guarantees for smooth tunnel excavation.

After completion, the G227 Line Laochengguan-Xining-Shangxinzhuang Highway will intersect with the Beijing-Tibet Expressway G6 Line, G109 Line, G341 Line, and the Zhangye-Wenchuan Liaison Line of the Beijing-Tibet Expressway (G0611). Once completed, the highway will further improve the province's national and provincial road network structure, promote the integrated development of trunk highways and urban roads, achieve effective connection between internal and external urban traffic, and effectively improve the speed and smoothness of Xining's external traffic.