On the morning of August 30, the two-lane tunnel of the Jiulongpo double-track tunnel on the north approach of the Lijiatuo double-track bridge, a municipal key project organized and constructed by Chongqing City Investment and Construction Co., Ltd., was successfully holed through, 30 days ahead of the planned schedule.

The north approach project of the Lijiatuo double-track bridge is located in Jiulongpo District, starting at the Qinglongzui interchange and ending at the north bridgehead of the Lijiatuo Bridge, with a total length of about 2.65 kilometers. The entire line is designed to urban expressway standards and includes one medium-length tunnel, one mainline viaduct, and one interchange.

"The tunnel is 670 meters long, and its upper section mostly consists of shallow-buried artificial fill, with the thinnest soil layer only 15 meters deep. The tunnel passes beneath the teaching building of the Electric Power School, a military management area, and several residential buildings, posing great difficulties for construction technology and management as well as coordination," said Chen Yong, project manager. To reduce the impact on the surrounding environment and residents' lives and ensure construction safety, Chongqing City Investment and Construction Co., Ltd., together with all participating parties, changed the originally designed blasting excavation to mechanical excavation and closely carried out in-tunnel monitoring and measurement as well as surface observation. The construction sequence was adjusted on site, with excavation during the day and support at night, to reduce nighttime construction and lower noise.

According to a relevant official of the Chongqing Municipal Housing and Urban-Rural Development Commission, the north approach project of the Lijiatuo double-track bridge is part of the Fourth Vertical Line of the expressway network. Once completed, the project will further improve the urban expressway network framework of Chongqing's central urban area, strengthen the rapid connection between Banan District and Jiulongpo District, ease traffic pressure on adjacent cross-river channels, and be of great significance to promoting Chongqing's economic development.