City to put more limits on skyscraper foundation pits

Shanghai will restrict the construction of large foundation pits for new building projects in an effort to reduce land subsidence hazards, city construction officials said yesterday.

Projects that involve building deep and large foundation pits inside the Outer Ring Road will be closely restudied by the watchdogs for their potential influence on the underground environment, while new approvals will be restricted, the government officials said.

The decision came after a 10-meter-long road crack emerged in the Lujiazui area, the city's financial zone, earlier this month. The incident made headlines and stirred concerns among local residents, prompting talk about whether high-rise construction fever should be cooled.

Not surprisingly, officials later concluded that the crack was the "result of the foundation ditch construction" of the Shanghai Tower project, which will be China's highest skyscraper, at 632 meters, upon completion by 2014.

Subsidence takes place when groundwater is pumped out, which happens for pit construction for the foundations of high-rises.

The higher the building, the deeper and larger the foundation pit must be dug. Many locals have called for a slowdown in the construction of high-rises and more efforts to control land slippage in downtown areas, especially in Lujiazui, famous for its skyscrapers.

Shanghai is among many Chinese cities with the same problem, as the pace of construction quickens.

A plan drawn up by more than 10 state ministries to deal with subsidence in China noted that more than 50 cities are experiencing growing land subsidence. The Yangtze River Delta region and the North China Plain area are among regions suffering the most.

Local authorities said the Lujiazui road crack would be repaired in March. They also said technical monitoring proved that nearby high-rises are in safe condition.

Despite stricter controls on deep pit construction, the government will not slow down its continuing building of more urban infrastructure projects. City officials said yesterday that legislators have approved spending 116.6 billion yuan (US$18.4 billion) on major infrastructure projects this year. The budget slightly outnumbers last year's, they said.

Most of the projects are aimed at improving traffic conditions and everyday life conveniences for the city's outlying districts and new towns.

Investment will cover 95 major projects including 27 new ones scheduled to kick off this year.

They include building new roads between the suburbs and downtown, as well as new facilities to improve the unstable quality of tap water for millions of suburban residents.

For transportation, new projects scheduled to launch later this year include the second phase of Metro Line 13 and the northern and southern extensions to the Jiading-Minhang elevated road.

Construction will also start on public support facilities in the Dongtan wetland on Chongming Island to facilitate development of "green" sightseeing programs in the mouth of the Yangtze River.