A Maine-N.H. Lift Span Retires Early Due To Stuck Sheave

摘要

A mechanical failure of a sheave in the south tower of the 76-year-old, 2,804-ft-long Sarah Mildred Long Bridge on Aug. 21 has led to a permanent closure-10 weeks before construction of its replacement would have closed it anyway. The steel-truss lift bridge carries 14,000 daily vehicles on the U.S. Route 1 Bypass over the Piscataqua River between Maine and New Hampshire. After two days of investigation, engineers from the New Hampshire Dept. of Transportation, MaineDOT, Hardesty & Hanover and contractor Cianbro determined the bridge would not be safe for operation without repairs that would cost $1 million and take at least six weeks. By Aug. 22, crews lifted the bridge into enough of an "up" position to allow ships to pass. Kaven Philbrook, Cianbro senior project manager for the $158.5-million replacement project, says that while demolition of the old bridge will start immediately, it will not impact new bridge construction, more than 50% complete.