|In Transit. Arched bridge segment was erected on land and moved to barges for transport to jobsite, where it was jacked into place.|
In an operation that altered the landscape of Providence, R.I. overnight, a contractor late last month wheeled a 5.5-million-lb bridge section onto specially equipped barges, then placed it onto 30-ft-tall piers as part of an $85-million contract.
The section is a 450-ft long, 160-ft wide, 85-ft high cable-stayed arched steel span. It is part of a 1,235-ft-long bridge, including steel box girders and precast concrete spans, that will carry a relocated section of Interstate 195 across the Providence River. Cardi Corp., Warwick, R.I., started work in winter 2003 on the key component of a $550-million program to replace the existing I-95 and I-195 interchange. Cardi opted to build the section off site. “When we put the contract out, we knew there was a possibility that someone might want to build it off site, so we had provisions in the contract to have land secured,” says James Caroselli, Rhode Island Dept. of Transportation chief civil engineer of construction operations.
The bridge was constructed at a former Seabees station in Quonset, R.I. “We built the bridge on temporary supports. The bridge sat on the bearings as we built it,” says Steve Cardi, executive vice president. During the construction process, meetings were held every month for two years to plan the move, he says.
Dutch subcontractor Mammoet brought in transporters—steel platforms mounted on multiple sets of wheels using independent hydraulic suspensions to maintain level—to move the section onto two 300 x 90-ft barges. “The two barges were linked like a catamaran with two crane booms and a pin connection,” says Cardi. Pumps moved ballast water in the barge to counteract the bridge’s weight. Then, the barges were towed to the jobsite where the bridge section was lifted and placed onto piers.
“We first installed [six] jacking towers up to a height of 30 feet,” says Cardi. Strand jacks on the towers lifted the section. Transporters, with attached cribbing and support structures, finished placement. The bridge was jacked up in 20-in. increments. Winches were used to slowly move the bridge into its proper alignment before crews lowered the bridge into place, using a low tide and ballast water to adjust placement.
The Aug. 28 installation went off perfectly, says Caroselli.
While the move itself went smoothly, the project encountered other challenges. Cardi’s contract rose to $93 million after it was forced to excavate submerged sheeting from an old hurricane barrier adjacent to the jobsite and from rising materials costs.
(Photos courtesy of Josh Edenbaum Photography & Digital Imaging