Bridge role for hoists
24 July 2014
Electric wire rope hoists supplied by Street Crane Company in the UK have been selected for a major role in the reconstruction of the 107 year old Longfellow Bridge over Charles River at Cambridge, Massachusetts.
The hoists are installed on a bespoke crane built by Street’s local partner Capco Crane and Hoist Company. The crane will play a pivotal role in the renovation of the bridge that spans 1.5 miles and carries around 90,000 people per day.
At 105 foot wide, the bridge carries both rail and road connections. Capco Crane has built a bespoke 40ft wide double girder gantry crane. This features twin Street 7.5t ZX hoists and a cantilever to accommodate a generator set for power. Using two hoists provides greater stability when handling large and ungainly loads. Due to structural limitations on the bridge, the hoists, used independently or in tandem, will be limited to 6t lifts and have a load summation device to prevent the limit being exceeded.
To meet the main contractor’s demanding schedule, fast delivery of the crane was critical. This meant that the hoists had to be supplied very quickly and Street were able to respond, delivering them just 12 days from receipt of order.
Operations are phased to permit continuing traffic flow. Work will entail in-place structural repair to the steel arches on the spans between ten granite piers, as well as the repair or replacement of spandrels, columns, stringers, floor beams and the concrete deck. Finally, the bridge will be refitted with cast iron fascias and pedestrian railings in the original style and the four characteristic pepper-pot towers, by which the bridge is locally identified, will be re-built.
The success of the gantry crane has prompted the main contractor to order a second crane to speed construction work and ensure that the bridge can be restored and brought back into full service again as quickly as possible. This will be delivered in the late summer.