The 1,300-foot-long bridge includes four travel lanes and a breakdown lane in each direction. The non-motorized lane is now part of the William Lloyd Garrison Trail, a shared-use pathway that provides a key link to local rail trails, including a 52.5-mile trail segment connecting Boston to Newburyport.
“It was understood that the tri-town area, separated by the Merrimack River, needed a north-south trail link,” Bertoulin said. “This desire to create a shared-use path led to an innovative approach where we could provide additional lanes to traffic, and then repurpose those temporary lanes as the shared-use path during the third construction phase, once the southbound span was complete.”
The project team used accelerated bridge construction (ABC) design techniques, where minimizing impacts on mobility took high priority in order to maintain traffic flow and prioritize safety for travelers during construction.
One of the effective ABC techniques was the use of precast decks for the bridge, which were transported in segments to the construction site once casting was complete.
“The precast deck design was chosen for its superior quality to cast-in-place decks,” Bertoulin said. “We were able to incorporate better casting and curing techniques, reduced shrinkage cracking, and ultimately reduce the overall construction time.”
Although there were some fabrication and transport problems that damaged a few panels, Bertoulin said those elements were identified early and corrected; either recast or repaired to meet project specifications without compromising quality.