A rendering of the Haimen-Taicang tunnel under the Yangtze River in East China's Jiangsu province. [Photo/WeChat account: tcfbgw]

The construction of an underwater tunnel connecting Taicang city and Haimen city in East China's Jiangsu province started on Sept 7, according to local media reports.

The tunnel will cost 43.4 billion yuan ($6.7 billion) to build.

With a maximum speed of 100 kilometers per hour and six lanes, the tunnel will be around 39 km long, including 11.2 km that runs under the Yangtze River.

There will also be a management center, a service area, two hazardous goods inspection stations, and five interchanges along the route.

The route is scheduled to open to traffic in 2028, and will be a landmark project featuring sophisticated shield tunneling, water repellent and fireproofing technologies, said Zhang Di, the chief designer. 

After completion, the tunnel will help promote the integrated regional development of the Yangtze River Delta and further improve the road network in the region.