China's deepest undersea tunnel borer kicks off from Nansha

The Pearl River DeltaTunnel of Shenzhen-Jiangmen Railway, China's deepest undersea tunnel, officially began boring on Dec 25.

The tunnel began construction is 115 meters beneath the water and started construction in July 2020.

A control project of Shenzhen-Jiangmen Railway, the 13.69-kilometer tunnel has a designated speed of 250 km per hour.

The Shenzhen-Jiangmen Railway is a major transportation infrastructure supporting the construction of the Guangdong-Hong Kong-Macao Greater Bay Area. The main route is 116 km long with seven stations including Xili, Shenzhen Baoan International Airport, Nansha, and Jiangmen.

An ultra-large shield borer named Dawanqu, which stands for the Greater Bay Area in Chinese, was applied in the construction.

Custom made for this project, the machine weighs 3,900 metric tons with a dimension 133 meters long and a diameter of 13.32 meters.