Hurrahs due completion of HZMB tunnel marvel

A cutting-through ceremony for the world's longest and deepest subsea tunnel will be held on July 7, the Hong Kong-Zhuhai-Macao Bridge (HZMB) Authority has announced.

Spanning 55 km, the bridge is the world's longest cross-sea infrastructure, the immersed tunnel of which sits between islands created in the east and west. The tunnel is 48 m below the Lingding Sea due to navigation requirements and the height limit imposed by airplanes.

Hong Kong-Zhuhai-Macao Bridge

The immersed tunnel is 6.7 km long and consists of a pre-embedded section, 33 prefabricated immersed tubes -- each with a displacement of 80,000 tons -- and a 12-m final joint weighing 6,500 tons.

The tunnel set records in the largest single tube dimension, most motor vehicle lanes, and longest lifespan with the most complicated manufacturing techniques.

With the engineered islands as east and west terminals, the tunnel is hailed as the core part of the HZMB project. It has been dubbed by experts as the "Mount Everest" in transportation engineering.

HZMB's under the rainbow [Photos by Chen Xinnian / Zhuhai Daily]

Several world marvels have been recorded during construction of the tunnel, for example, creation of two new islands within a year, an elevation error of ±4 cm of 33 immersed tubes, qualified rate of 100 percent, error of around 1 mm in tube connection, and impermeable characteristics. The tunnel was cut through to access the two artificial islands as of July 2, marking a significant milestone.

With six dual lanes, design speed of 100 km/h, and service life of 120 years, the tunnel satisfies accepted standards of waterproofing, fireproofing, anti-explosion, anti-collision, and avoiding damages caused by anchors. Furnishing of the tunnel and the two islands will be sped up, and endeavors will be made to prepare the bridge for opening by year's end, said an official from the Bridge Authority.