The 3,254-ft-long, 78.5-ft-wide current crossing carries about 32,000 vehicles per day on Route 3A over the Fore River, south of Boston. The $244-million project was 88% complete in September and will open for traffic by June 2018, says Michael McGrath, deputy chief engineer for construction with MassDOT.

The White-Skanska-Koch joint-venture team is replacing the current temporary Fore River Bridge with a permanent steel-vertical-lift bridge. The replacement bridge, not including approach spans, has an estimated life of 75 years.

In summer 2014, eight 85-ton replacement counterweight sheaves for both bridge towers were delivered, but the fabricator, Russellville, Ala.-based G&G Steel, discovered cracks in the welds. The sheaves had to be replaced in December 2015, according to a MassDOT spokeswoman. G&G Steel did not respond to an ENR inquiry regarding the fabrication problem. “MassDOT conferred with the contractor [White-Skanska-Koch]. The responsibility for this issue was not agreed upon,” she says. “The contractor did not want to move forward until the cause of the cracking was evaluated,” which contributed to the delay.

MassDOT would not respond to questions regarding potential additional costs or litigation.

The Float-In

After months of planning, the 2.9- million-lb center span for the Fore River Bridge replacement was successfully floated in and installed on the new superstructure on Aug. 15.

McGrath notes that, while rolling down the center-span structure onto the twin barges at the old Fore River Shipyard in Quincy, “400,000 gallons of water was moved around as ballast to counteract the span’s weight. We budgeted two hours to move the span from the slip to the bridge, starting at 3 a.m.” By the time McGrath arrived just past 4 a.m., the span—fabricated by Oregon Iron Works, which was acquired by Clackamus, Ore.-based Vigor in 2014—was assembled and already in place in preparation to lift.

“The weather was perfect, the water was like glass, and the wind was only 7 miles per hour after concerns it could be 15 miles per hour,” McGrath says.

The 324-ft-long, 78.5-ft-wide lift span varies in height, from 33.5 ft at each end to 43.5 ft at its center. During the float-in, “four tugboats were pushing the twin barges, tied together with a structural system and floated through sideways next to the towers,” McGrath says.

He says that, once the tide rose to 12 ft, “the water naturally lifted the span into place between the towers. Ironworkers were on both sides. As the span came to the right location [beside the superstructure], we began slowly pulling out sections of the temp support towers,” McGrath says. The crew used self-propelled mobile transporters to lift the span off the temp supports and shifted it into position on the bridge tower’s bearing points.

Crews now are working on fine-tuning the lift span, with “lots of tweaks to the approaches on either side,” McGrath notes. Next, they will start casting concrete for the lift-span deck.

The new bridge is the third movable bridge in the same location. MassDOT replaced the first 1902 swing bridge with a bascule bridge in 1936, due to navigational hazards. In 2002, the agency re­directed traffic onto a temporary bridge, which was demolished in 2004. The 15-year-old temporary bridge has reached the end of its useful life and requires frequent partial closures.