Building the World's Widest Immersed Tube Tunnel

THE world's widest immersed tube tunnel is currently under construction in China.

The tunnel forms part of a larger crossing, intended to connect cities within the Pearl River Delta.

Linking Zhongshan with Shenzhen, the new connection crosses the Pearl River some 38 kilometres north of the Hong Kong-Zhuhai-Macau crossing.

Above: The new Zhongshan-Shenzen crossing will span the Pearl River estuary (image courtesy of New China).

However, unlike the Hong Kong-Zhuhai-Macau crossing, which connects the country's two Special Administrative Regions (SAR) to one another and to mainland China, this crossing will connect two cities fully under Chinese jurisdiction.

Above: The new link consists of a bridge section, as well as a tunnel (image courtesy of New China TV).

The Pearl River Delta Metropolitan region is attracting increased infrastructure investment from the Chinese government, to allow it to function as a single megacity.

The new Shenzhen-Zhongshan crossing is part of this initiative, along with the Second Humen Bridge.

Above: The tunnel's hollow steel sections are being transported closer to location, where it's walls will be filled with concrete ( image courtesy of New China TV).

Construction on the 24-kilometre Shenzhen-Zhongshan bridge started in 2016 and is expected to complete in 2024.

The eight-lane highway then dips into a 6.8-kilometre long tunnel, leaving a clear path for shipping traffic on the Pearl River.

Above: The tunnel will be up to 55.46 metres wide, making it the widest of its kind (image courtesy of New China TV).

The tunnel is made up of 32 sections of prefabricated immersed tubes which vary in width from 46 to 55.46 metres, making it the widest tunnel of its type.

Above: The new bridge and tunnel entrance (image courtesy of New China TV).

Once completed, travel time between the two cities will drop from two hours to just 30 minutes. The crossing will also alleviate traffic congestion along other crossings.

Learn more about the vast Hong Kong-Zhuhai-Macau crossing in our documentary: