Workers celebrate as the 3,000-ton super shield starts digging the Beiheng Passage near the Suzhou Creek yesterday.(Xinhua)
Shanghai's biggest tunneling shield started digging through the west downtown area and under the Suzhou Creek yesterday to build a new east-west thoroughfare.
The six-story, 3,000-ton super shield will tunnel through about 8 kilometers from Zhongjiang Road and Guangfu Road W. through Changhua and Changshou roads in Putuo District, the Shanghai Tunnel Engineering Co said.
"The shield, being equivalent to about 400 elephants, will create a six-lane underground expressway with a designed driving speed of 60 kilometers per hour," said General Manager Ling Yufeng.
The underground section is the biggest challenge for the under-construction Beiheng Passage, a 19.1-km road linking Changning, Putuo, Jing'an, Huangpu, Hongkou and Yangpu districts, Ling said. It is due to be finished by the end of 2019.
The shield will dig beneath Metro lines 3, 7 and 11, and lines 14 and 15 that are about to begin construction. It will also dig beneath the Suzhou Creek and its anti-flood wall, along with about 100 homes and various pipelines, Ling said.
As part of the project, the shield will have to dig through a 5.5-km stretch of sandy soil, which creates difficulties in stabilizing the tunnel and requires the shield to frequently change direction.
The shield will dig for about 1.3 kilometers beneath the Suzhou Creek. Workers will build a coffer dam — basically, a pit which is pumped dry of water — at the east section of the creek. The river has been cut off and construction on the coffer dam will begin soon, the company said yesterday.
When finished, the Beiheng Passage will become a major east-west thoroughfare to relieve the traffic congestion on the Yan'an Road Elevated Highway, the northern part of the Inner Ring Road as well as other busy north-south routes, the company said.