A large U-shaped tunneling shield completed excavation of a railway tunnel in northwest China's Shaanxi Province Friday.
The U-shaped machine, 10.95 meters high, 11.9 meters wide and 110 meters in length, is an improvement on the traditional round tunnel boring machine. Its shape and design were customized for the construction of Baicheng Tunnel on the Loess Plateau, where the soil is powdery and dry.
It is the first U-shaped tunneling shield of such big size in the world, according to China Tiesiju Civil Engineering Group, the contractor.
The machine began work on the 3.3-kilometer Baicheng Tunnel in November 2016.
The machine significantly reduced the excavation time and engineering costs compared with round tunnel boring machine.
Baicheng Tunnel is part of the Menghua Railway, a coal transport route linking Inner Mongolia with Jiangxi Province.