From Wikipedia, the free encyclopedia
The Orwell Bridge from Orwell Country Park
The Orwell Bridge was opened to road traffic in 1982 and carries the A14 (then A45) over the River Orwell just south of Ipswich in Suffolk, England.
The main span is 190 metres which, at the time of its construction, was the longest pre-stressed concrete span in use. The total length is 1,287 metres from Wherstead to the site of the former Ipswich Airport. The width is 24 metres with an air draft of 43 metres. Pilings were sunk 40 metres into the river bottom. The main contractor was Stevin Construction B.V. - a Dutch company.
Construction of the bridge commenced in October 1979 and was completed in December 1982. The main span was constructed by using a balanced cantilever technique, casting sections on alternating sides of the pier in a weekly cycle.
The bridge is constructed of a pair of continuous concrete box girders with expansion joints that allow for expansion and contraction. The girders are hollow, allowing for easier inspection, as well as providing access for services, including telecom, power and a 711mm water main from the nearby Alton Water reservoir. The necessary inspections still cause major disruption to traffic every six years; during the last inspection in the summer of 2005 the delays caused by lane closures and speed restrictions added between 30 to 60 minutes to journey times during the peak commuting periods.