China opens its longest underwater road tunnel

6 January 2022

China has opened its longest underwater highway tunnel after only four years of construction below one of the country’s largest freshwater lakes – Lake Taihu in the Yangtze Delta.

Construction of the 10.79km-long Taihu Tunnel began in January 2018. It has been built at a cost of around US$1.56bn and involved the use of over 2,000,000m3 concrete. A total of six lanes of bi-directional 100km/hr traffic will flow in the 17.45m-wide tunnel, all under a glowing ceiling of coloured LED lights designed to combat driver fatigue, reported Xinhua – China’s official news agency.

Waterproofing the tunnel was one of the biggest engineering challenges as it lies up to 20m below the lake bed, reported China Daily. Handling the huge amounts of concrete required the project contractor to develop new methods of processing and an intelligent, real-time monitoring system for the pouring of the concrete. The contractor also operated a totally enclosed concrete mixing plant to eliminate dust and noise in order to protect the ecology of the lake.

The three tunnel ventilation shafts have been integrated into the landscape: the one at tunnel mid-span surfaces via a small man-made island; while on the western side the shaft surfaces through a conch-shaped statue; and on the eastern side has been designed to resemble an ancient boat.
The Taihu Tunnel forms part of the 43.9km Changzhou-Wuxi Highway project which opened on 30 December 2021, and is expected to draw together the cities of Shanghai, Nanjing, Suzhou and Wuxi, as well as boost the regional economy.