Dabao Expressway is a section of Hangzhou-Ruili (G56) Highway, the main national highway, which is connected with Chuda Expressway with a total length of 166 kilometers. The first phase of the project started on December 18, 1998, and the second phase started in May 1999, and on September 29, 2002, the whole line was opened to traffic on a trial basis. Dabao Highway is the first highway across the Hengduan Mountains, the line is mainly laid in the “V” shaped canyon, along the route of the loose geological “Western Yunnan red layer”, the maximum excavation depth of the roadbed up to 135 meters. Due to landslides, the highest slope up to 268 meters, and bridges, tunnels mileage up to 34.612 km, so the construction is difficult.