Providence River Bridge

The Providence River Bridge was designed as a 1,235-foot-long, 164-foot-wide tied network arch bridge with an 80-foot-high, 400-foot arch span, creating a slender and graceful structure that serves as an entrance to Providence's Old Harbor. The Rhode Island Department of Transportation oversaw a citizens' committee that reviewed several bridge designs submitted by the Maguire Group and William D. Warner, Architects and Planners, and under the department's guidance selected the tied network arch form, commonly used in Europe. Its diagonal cables cross each other at least twice, and the bottom ends of the arch are linked by a tie beam that absorbs the arch's outward thrust. The Federal Highway Administration provided most of the project's funding. Construction followed an unusual strategy that reduced the schedule by a full year: instead of building the bridge over open water in Providence, it was built on land at Quonset Point in North Kingstown and then towed to Providence on barges. Skilled ironworkers in Plainville, Connecticut, crafted the arch piece by piece by cutting steel plate on a 170-foot-long table. Each arch beam section was a curved steel box 4 feet high and 3 feet wide, and the welded pieces formed a 400-foot multiple arch containing 5.5 million pounds of steel. After assembly into sections about 50 to 100 feet long, the pieces were trucked to Quonset Point, lifted by crane onto temporary steel towers, and bolted together by ironworkers hoisted 80 feet in the air to create single arches. Altogether, the bridge members were connected with 65,000 bolts. For the final move, the Rhode Island Department of Transportation and the Cardi Corporation chose Mammoet, a Dutch-based company, to transport the tied arch span 12 miles north over Narragansett Bay. Before towing, Mammoet used computerized diesel-powered hydraulic jacks on six jacking towers to raise the 5.5 million-pound bridge 30 feet, pulling it upward about 20 inches at a time so it could clear the concrete piers at the bridge site. The span was then lowered onto six computer-controlled self-propelled transporters, moved from the pier onto two adjacent 300-foot-long barges, and towed by four tugboats to its final destination in Providence.

Providence, Rhode Island · United States