The Hong Kong-Zhuhai-Macao Bridge (HZMB), crossing the Pearl River Estuary and linking Hong Kong to the East, and Zhuhai and Macao to the West, is a combination of bridges, a tunnel and artificial islands. It is an ongoing infrastructure project as momentous as the previous Three Gorges, Qinghai-Tibet Railway and Beijing-Shanghai Express Railway projects, which have become established as some of the most significant mega projects completed since the founding of the People’s Republic of China. With an investment of approximately RMB 105 billion, this crossing consists of three parts: the Offshore Bridge-and-Tunnel (the Main Bridge); the three Boundary-Crossing Facilities (BCFs) in Hong Kong, Zhuhai and Macao; and the Link Roads into the three regions. The Island-and-Tunnel Section, a key part of the Main Bridge, includes two artificial islands and an immersed tunnel. This section is 7440.546m in length, of which the immersed tunnel is one of the most challenging constructions of its kind undertaken in the world to date. The construction period of the Island-and-Tunnel Section is scheduled from December 2010 to March 2016, altogether 63 months. The design and building task of the Section is being carried out by a Joint Venture led by China Communications Construction Company (CCCC).
The ventilation and safety design for such a long immersed tunnel (6.7km) is admittedly a tough problem in the international engineering community. Additionally, the precasting of the gigantic concrete tunnel elements, their towing and immersion under complicated sea conditions, the connection of tunnel elements under high water pressure, and the watertightness and durability of the element joints all call for the highest world standards. The control of differential settlement from the soft soil tunnel foundation, the control of differential settlement at each part of the Eastern and Western Artificial Islands, the connection of the immersed tunnel and the artificial islands, and the reliability and durability of the tunnel and islands during the operation phase all present daunting challenges.
Constructing large scale of works under a tight schedule, overcoming technological challenges and managing high risks are common to almost all mega projects. However, this project also features a design-and-build contract, coordination of the three regional governments in the construction and management, and close attention from the society. Moreover, there are environmental constraints as the alignment runs across the national conservation area for the Chinese white dolphins, as well as complicated navigation traffic conditions as the route crosses the busiest shipping area of the Lingding Sea.