High quality was maintained in constructing the Big Hengqin Mt Tunnel despite work falling behind two months, it was affirmed by experts at a Sept 14 conference concerning the safety and quality of Zhuhai engineering projects. 

The dual tunnels were broken through in December and March and will open to traffic by the end of this year as scheduled. To compensate for the delay caused by COVID-19, on Feb 16 the project was the first in Hengqin New Area to resume construction, having implemented automatic mechanized construction to increase efficiency. 

Tunnel entrance [Photo by Chen Xinnian / Guanhai App]

Chief engineer Su Guangming said that automatic machines save 5 million yuan ($737,000) and increase efficiency by more than 200 percent in the construction of every kilometer of tunnel compared with a manual labor force.

According to project manager Hao Deliang, the builders faced serious technical challenges. The 358-sq-m (428-sq-yd) excavated cross-section is equivalent to the surface of a basketball field, while the minimum net distance between Tunnels 1 and 2 was achieved at .54 m (1.77 ft).

In addition, the Big Hengqin Mt Tunnel had to pass over the Chimelong Tunnel and beneath both Zhuhai Airport Urban Rail Transit Phase II and Tiantai Mt Reservoir with gaps of 20.9 m (67 ft), 3.5 m (11.4 ft), and 144 m (471 ft) respectively.

China Railway 16th Bureau Group reports having introduced mature and rigorous rail system standards for tunnel construction, promoted the use of Building Information Modeling (BIM) technology, and improved concrete durability through cooperation with universities. To date, the project has obtained four national invention and five utility model patents, with no occurrence of accidents.

The 4.9-km (3-mile) passageway connects Hengqin and Central avenues in the north and a purposed South Qinhai Road in the south. It will be a key artery between Hengqin Island and the South Reclamation Area.