A composite single-leaf bascule drawbridge, renovated with composite components manufactured by pultruder Strongwell (Bristol, Va.) has, in the short time since project completion in 2006, earned an exemplary reputation in the infrastructure market for composites.
The object of renovation was the Chamberlain bascule bridge, located in the Caribbean town of Bridgetown, Barbados. “Bascule” is the common term given to counterweighted bridge spans that swing upward to allow ship traffic to pass. The Chamberlain bascule measures 29 ft/8.9m wide, 38.5 ft/11.7m long and about 3 ft/1m deep and is primarily used by pedestrians, although it was designed to support vehicles. The original steel bridge, however, had dangerously deteriorated due to saltwater corrosion.
The new structure was formed using Strongwell’s trademarked COMPOSOLITE building panels and EXTREN structural shapes. Conceived years ago by British engineering firm Maunsell (now Faber Maunsell, St. Albans, Herts, U.K.), the bridge’s deck design comprises a heavy-duty version of COMPOSOLITE hollow deck panels, pultruded with internal structural ribs. One set of panels runs longitudinally, and a second set runs transversely above the first, to form the deck, explains Strongwell’s Glen Barefoot. Panels are joined with integral toggles that are adhesively bonded and fastened with three-way composite connectors. EXTREN square tubing forms the deck’s decorative railing system.
Thanks to the new deck’s low weight, the counterweighted lifting mechanism did not have to be replaced, saving the town’s government a considerable sum. That and the structure’s low maintenance requirements and attractive aesthetics earned it “Best of Show” honors in the Awards for Composites Excellence (ACE) competition, at the American Composites Manufacturers Assn.’s (ACMA) COMPOSITES & POLYCON 2006 trade show in St. Louis, Mo.
Strongwell recently replaced the deck on the 106-year-old Hawthorne Street bridge in Covington, Va. Listed on the National Historic Bridge Register, the bridge had a badly deteriorated concrete deck. The deck was replaced with EXTREN square tubes. The weight savings helped to lengthen the useful life of the bridge, which features a rare truss design.
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