A CRACK up to 10 meters long on a main road in Lujiazui sparked safety concerns in the skyscraper area yesterday (16 Feb 2012) after pictures were posted online.
The crack was spotted at an exit of the Shanghai World Financial Center opposite the under-construction Shanghai Tower.
"It has been here for a while," a member of staff at a hotel in the financial zone told Shanghai Daily.
However, the company that is building the Shanghai Tower said the crack was normal subsidence during the construction of the tower's foundation ditch, which is "under control."
So far the underground structure of the building has been finished and the element that caused the subsidence should be gone, the company said last night via the Shanghai government's official microblog account.
Repairs should be started soon once the rainy weather improves, the company said.
Construction of the Shanghai Tower, which will be the tallest building in China by 2014, has been strictly monitored since the beginning, and this would not end despite the completion of the foundation, the company added.
The Lujiazui area, which is now experiencing massive construction both above and beneath the ground, has long been at the center of debate over whether construction work could lead to subsidence problems.
Below ground, five underground passages and a transit hall are being built to connect the skyscrapers and Metro stations.
Above ground, the Shanghai Tower has reached a height of more than 200 meters of its intended 632 meters.
Experts said that the loose earth structure in Shanghai and improper construction methods were very likely to trigger subsidence, especially uneven subsidence, which is more dangerous.
Xu Liping, general engineer of Shanghai Geotechnical Investigations & Design Institute, said: "The soil in Shanghai is soft and the construction around or under is likely to cause cracks in certain places."
But Xu said that determining the cause of the current crack could be a complicated process that not only required the involvement of relevant parties around the crack but a calculation of the influence of the construction work as well.
Shanghai is taking active steps to tackle its subsidence problem.
One way that has proved effective is to pump back groundwater drained during construction.
Cracks and cave-ins, caused by subsidence, have frequently made headlines in the city.
In October last year, a large piece of the road surface at a busy intersection collapsed in downtown Zhabei District.
Local urban maintenance department officials said loose sand and earth beneath was to blame.
Vice Mayor Zhang Xuebing has told local lawmakers the city is controlling the number of projects, with no more than 10 percent of roads affected by construction at any one time.