Chinese-made tunneling machine passes milestone

The world's largest shield machine for railway construction, a tunneling device with a diameter of 15.4 meters, excavated its 1,000th ring segment on Sunday to reach 2 kilometers, a milestone in the construction of a tunnel beneath the Yangtze River for a high-speed railway.

The achievement also means that the shield machine, called Linghang, which was independently developed by China, is pressing ahead to a higher level of construction difficulty, according to China Railway Tunnel Group Co, constructor of what will be a 14.25-km underwater railway tunnel linking Shanghai's Chongming Island with Taicang, a city in Jiangsu province.

"With a gradual, slight downward slope, the pressure from the surrounding water on the construction project is escalating. Many parts of the tunnel to accommodate railway tracks in both directions are to be built at 89 meters underneath the river, where the water pressure is 0.9 megapascal — as enormous as holding six people on a fingernail," said Fu Bowei, the project's deputy chief engineer.