One of the world’s longest ocean-crossing bridges has opened to traffic in China’s Hangzhou Bay after five years of construction, though work continues on an island service area.
Engineering Const. HQ of Hangzhou Bay Bridge
Box girders were erected with a barge crane.
The 36-km-long, six-lane Hangzhou Bay Bridge, linking Ningbo’s Cixi county in the south to Jiaxing in the north, opened to traffic in May at a cost of $2 billion, says Zhongda Lu, chief engineer for the Engineering Construction Headquarters of Hangzhou Bay Bridge, the construction manager. Among the many private investors contributing almost half the budget for the tolled crossing, Ningbo Communications Investment Holdings Co. Ltd. is the largest shareholder.
The S-shaped bridge is second only to Louisiana’s Ponchartrain Causeway by four km in length and has a vertical clearance of 60 m. Its 448-m-long north main span and 318-m-long south main span are comprised of 37 m x 3.5 m x 15 m cable-stayed steel girders. A pair of pylons in an A shape rise 130 m above the north span deck and 160 m above the south span deck. The rest of the crossing consists of precast prestressed, concrete box girders up to 70 m long and 2,000 tonnes, erected with a 3,000-ton barge crane.
Engineering Const. HQ of Hangzhou Bay Bridge
Engineering Const. HQ of Hangzhou Bay Bridge
New 36-km-long bridge over Hangzhou Bay has opened to limited traffic. It will include an island facility (above) offering food, lodging and an observation tower, to be completed in 2009.
Due to fast-moving currents and tides almost 8 m high, the design team of China Highway Planning and Design Institute Consultants Inc. (HPDI) and China Zhongtie Major Bridge Reconnaissance & Design Institute Co. Ltd. (BRDI), opted for off-site fabrication of over 900 segments. It worked closely with the key contractors, China Communications Construction Co. Ltd. and China Railway Engineering Group Co. Ltd.
“Constructibility was the key focus on this project from the very beginning,” says Lu. The team drove thousands of 80-ft-long spiral submerged arc-welded (SSAW) steel-pipe piles with 1.6-m dia. and thickness of about 20 mm using customized 1,800-ton pile drivers. Three layers of epoxy-resin powder coatings should enable the pipes to survive the corrosive marine environment for a 100-year design life, says Lu.
An area of toxic methane discovered 50 m underground made drilling especially difficult. Sixty-cm-dia. steel pipes were inserted to slowly release the methane six months prior to drilling.
The 10,000-sq-m island service area located mid-bridge will provide food, lodging and an observation tower. “The foundation is completed and we are starting the superstructure portion. It is scheduled to open by the end of 2009,” says Tao Chen, assistant project manager.
The trip from Ningbo to Shanghai and southern Jiangsu once involved a detour of 400 km. The bridge reduces that distance to 80 km.
