The undersea tunnel of the Hong Kong-Zhuhai-Macao Bridge was connected on July 7, which also means that the main project of the bridge will achieve full completion. The Hong Kong-Zhuhai-Macao Bridge is the world's longest sea-crossing bridge, with a total length of 55 kilometers, consisting of bridges, islands, tunnels, and connecting lines to Guangdong, Hong Kong, and Macao.
First, let's take a look at the Hong Kong-Zhuhai-Macao Bridge from a drone aerial view!
CCTV reporter Zhao Zhongliang: This is the Hong Kong-Zhuhai-Macao Bridge over the Lingdingyang Channel, and it is also the world's largest sea-crossing bridge-island-tunnel project to date. After passing through 22.9 kilometers of bridges, the Hong Kong-Zhuhai-Macao Bridge will transition into the undersea tunnel section here. This 6.7-kilometer undersea tunnel, after long-term installation, preparation, and debugging, will reach the milestone of breakthrough.
The Hong Kong-Zhuhai-Macao Bridge, with a total length of about 55 kilometers, includes the main project of the sea bridge-island-tunnel and the connecting lines of Hong Kong, Zhuhai, and Macao. Among them, the island and tunnel project, as the core control project of the Hong Kong-Zhuhai-Macao Bridge, includes two artificial islands each with an area of 100,000 square meters and a 6.7-kilometer undersea immersed tube tunnel. This is also the immersed tube tunnel with the greatest burial depth and the highest comprehensive technical difficulty in the world today.
Lin Ming, Chief Engineer of the Island and Tunnel Project of the Hong Kong-Zhuhai-Macao Bridge: The main project is basically completed, including the main structures of the islands and the tunnel. For the ancillary works, we mainly have 70,000 square meters of buildings on the islands. According to our plan, the entire project of the two islands has now reached the final sprint stage.
Reporter explores the 6.7-kilometer undersea tunnel
The undersea tunnel of the Hong Kong-Zhuhai-Macao Bridge is 6.7 kilometers long, the world's longest highway immersed tube tunnel and the only deep-buried immersed tube tunnel, and also China's first offshore immersed tube tunnel.
The undersea section is about 5,664 meters, composed of 33 giant immersed tubes and one final joint of the closure section, with a maximum installation depth of more than 40 meters. What does it feel like to travel under the sea? How is safety ensured?
CCTV reporter Li Weidai: Departing from the Zhuhai direction and driving 22.9 kilometers on the bridge deck, we arrived at the West Artificial Island, where the Hong Kong-Zhuhai-Macao Bridge transitions from bridge to undersea tunnel. From here begins the 6.7-kilometer undersea tunnel journey.
To reduce the driver's discomfort from light changes when entering and exiting the tunnel, a "door-shaped" light-reducing hood has been built at the tunnel entrance to achieve a gradual light transition. Entering the tunnel, the 37.95m wide and 11.4m high undersea tunnel offers a broad view, equivalent to a 4-story building height, and can accommodate six lanes in both directions.
CCTV reporter Li Weidai: Now our vehicle has reached 40 meters below sea level. Compared with the ground, there is nothing unusual here; the air is very circulating and even cooler.
With the relay effect of a fan every 300 meters, fresh air from the ground is continuously supplied to the undersea tunnel. At the same time, the fire protection, communication, power, and other systems inside the tunnel ensure the safe and smooth operation of the tunnel at all times.
CCTV reporter Li Weidai: In the undersea immersed tube tunnel of the Hong Kong-Zhuhai-Macao Bridge, every 135 meters there is such a safety door. Inside is not only an emergency escape passage but also a comprehensive utility gallery with rich contents.
Yin Haiqing, Deputy Chief Engineer of the General Project Management Department of the Island and Tunnel Project of the Hong Kong-Zhuhai-Macao Bridge: It is divided into three layers. The top layer is called the smoke exhaust duct, where smoke is discharged from above in case of fire; the middle section is the escape passage, and under the cover plate are communication cables, optical fibers, including fire pipes, etc., equivalent to our nervous system.
With the guarantee of a sensitive nervous system, the tunnel's "skin" and other parts must also withstand tests. From wall panels to ceilings, the fireproof facilities laid in the tunnel can ensure the safety of the main structure under 1200 degrees Celsius for 2 hours. At the same time, automatic sprinkler systems, emergency rescue phones, etc., are all simultaneously ensuring driving safety in the tunnel. The undersea tunnel of the Hong Kong-Zhuhai-Macao Bridge is 6.7 kilometers long, and it takes 5 to 6 minutes by car to complete the magical undersea journey.