The Beijing Railway Administration's underground diameter line is an important underground project connecting Beijing Railway Station and Beijing West Railway Station. The line has a total length of 9,151 meters, of which the tunnel is 7,285 meters long, with a maximum excavation depth of 41 meters and a minimum cover thickness of only 1.5 meters. This line is Beijing's first single-tube, double-track electrified railway tunnel. Its completion and commissioning are of great significance for improving the railway hub in the Beijing area, alleviating pressure on urban surface traffic, and achieving connection between the two stations.

　　At the breakthrough site, Cheng Mingliang, commander of the Beijing Underground Diameter Line Project Construction Headquarters, said that this project can be regarded as the most difficult in China in terms of both construction difficulty and technological content. A risk assessment was carried out for the entire line to ensure the smooth breakthrough and commissioning of the tunnel. After the underground diameter line begins operation, it will provide convenience for passengers transferring between the two stations and alleviate surface traffic pressure between Beijing Railway Station and Beijing West Railway Station.

　　He Feng, project manager of the China Railway Tunnel Group, focused at the site on explaining to reporters the difficulties faced during tunnel excavation and the efforts made by construction personnel. Because the project needed to pass beneath existing subway lines such as Beijing Subway Line 2 and Line 4 without causing adverse effects on them, the tunnel excavation encountered great difficulties. With the assistance of military personnel and research departments of relevant universities, the construction personnel ultimately used new technologies to effectively control settlement and deformation and completed the tunnel construction.

　　The project is organized for construction by the Beijing Railway Administration, designed by the Third Railway Survey and Design Institute Group, and jointly constructed by China Railway Tunnel Group, China Railway 16th Bureau Group, China Railway Sixth Group, and China Railway Electrification Bureau Group. It is planned to be officially opened for operation in 2015.