The insane £15bn bridge that’s the world’s longest sea crossing stretc | World | News

The bridge crosses the Lingdingyang channel in the Pearl River Estuary and holds the record as the longest bridge-tunnel system sea crossing in the world.

It is made up of the 7.4-mile (12km) Hong Kong Lind Road, 18.3. mile (29.6km) Main Bridge and 8.3-mile (13.4km) Zhuhai Link Road.

HZMB connects major cities in the Pearl River Delta to Hong Kong – taking only 40 minutes to cover the roughly 26-mile (42km) distance from Hong Kong Port Zhuhai Port and Macao Port.

The viaduct section of the structure includes three cable-stayed bridges: Qingzhou Channel Bridge, Jianghai Channel Bridge, and Jiuzhou Channel Bridge.

Out of the three, the Qingzhou Channel Bridge has the longest span of around 458m long.

The Jianghai Channel Bridge’s steel towers weigh around 3,100 tonnes. The steel used for the bridge’s decks totals a huge 420,000 tonnes – equivalent to the weight of 60 Eiffel Towers.

The bridge deck area measures 700,000 square metres, matching the size of 98 football pitches, and the total weight of the bitumen used to service the roads is about 100,000 tonnes.

The tunnel is located in a section of open sea, with a maximum water depth of 45 meters. Engineers had to overcome technical difficulties to complete the tunnel, including strong winds and water currents.

The size of a standard tunnel segment is about 180m long by 38m wide and 11m high. Each bit weighs 80,000 tonnes.

Tunnel segments were precast at a yard on Guishan Island and then taken by tugboats to the construction site to be placed in their final position.

According to the authorities, the final connection of the tube tunnel proved to be challenging,

Prefabricated steel structures were used so the need to work deep underwater could be reduced and construction time shortened.

With the final connection weighing as much as 6,000 tonnes, the contractor employed the largest lifting barge in the world to install this last part.

However, the contractor faced challenges such as airport height restrictions, unstable water currents, and the need for a tight tolerance of ±25mm to connect the final part.