Nanchong-Chengdu Expressway is a part of comprehensive transportation corridor, a country with ten vertical and ten horizontal lines along the river, and an important section of the east-west horizontal line of the national expressway network, which has a significant position in the national and regional expressway network. After the highway was completed and opened to traffic in 2002, with the rapid development of regional economy and society, the traffic volume has increased rapidly, and it has become one of the busiest and most congested highways in the province, and it is urgent to implement capacity expansion and reconstruction.
The whole line of Chengnan Expressway is widened by the original road, and some double tracks are built for expansion construction. The expansion route starts from Nanchong Dongguan Hub Interchange, passes through Hanjiawan, Gaoping, Jialing, Pengxi, Tangjia, Daying, Cangshan, Huaikou and Qingquan, and ends at Chengdu Ring Expressway Luosiba Hub Interchange. The total expansion and construction scale is 240 kilometers, of which the original road is widened and reconstructed 177 kilometers. The third bid section of the newly-built double-track railway is 63 kilometers, which is the transit section of Nanchong City, the transit section of Daying County and the section of Chengdu entering the city. According to the result of traffic volume forecast and its function in the road network, different technical standards are adopted for the expansion project. The original road expansion adopts two-way eight-lane technical standards, and the construction period of each bid section is 36 months.