As a key national development project attracting worldwide attention, Qinling Zhongnanshan Tunnel is the largest tunnel in the world adopting the double caves and single direction of lane.

With a total length of 255 km, Xian-Hanzhong Expressway is an important section of the Beijing-Xian-Chengdu-Kunming Expressway.

As one of the large scale tunnel groups in China, Shanghai-Chengdu Expressway Tunnel Group has the total construction length of 180 km with the tunnel group comprising of 16 tunnels.

Tongling-Tangkou Expressway is one of the important roads in the southern Anhui district. With a total length of 121 km, it is comprised of 14 tunnels while the accumulative length of the single cave tunnels of 16.8 km.