The opening of the new $318 million steel arch bridge, located along Interstate 95 between Newburyport and Amesbury, was celebrated at an Oct. 30 ribbon-cutting event that included participation by Massachusetts Gov. Charlie Baker.

This project consisted of replacing the existing John Greenleaf Whittier Bridge; widening and improving a four-mile section including interchange improvements and highway lighting of I-95 in Newburyport, Amesbury, and Salisbury; and replacing four adjacent bridges.

WSP USA, as the project preliminary designer and environmental permitting engineer developed the design-build procurement documents and continued throughout the project as the owner’s engineer, working on behalf of the Massachusetts Department of Transportation (MassDOT). WSP developed the plan to replace the original six-lane, double-arch bridge as part of MassDOT’s $3 billion accelerated bridge program.

“The project started as an idea to simplify construction staging and design by building the new northbound bridge wide enough to replicate the existing six-lane travel configuration in an interim condition, allowing for the demolition of the existing double arch in a single demolition phase,” said Mike Bertoulin, WSP project manager. “The southbound bridge could then be constructed, opened and the northbound bridge would be reconfigured to its final four-lane design. The extra staging lane took over 30 months off the project schedule and was repurposed into a shared-use path.”

This innovative staging solution eliminated any construction phase traffic impacts to this busy commuter and regional recreational corridor to New Hampshire and Maine. “The project’s architect, Jeff Lowe, from that starting point, worked with the design team and developed a vision that became a reality,” Bertoulin said. “It became the first MassDOT bridge to add alternative travel to an interstate bridge replacement.”

Built in 1951, the steel arch bridge had been declared structurally deficient. In 2013, work began on designing an eight-lane replacement bridge that would improve safety, improve traffic flow, meet current bridge construction standards, improve air quality by reducing I-95 congestion, and support non-motorized transportation.

When the decision was made to build a new bridge, eight design options were considered. Ultimately, MassDOT chose a twin network arch design, after public sentiment favored a bridge that maintained the historic integrity of the original.

“The community sought a structure that was reminiscent of the original historic bridge and the elegance of an arch was key to community support,” Bertoulin said. “It is a modern design with a classic historic appearance; aesthetically pleasing without obstructing the surrounding landscape.”

Public participation was a key part of the process, as the removal of the existing historic bridge was an adverse impact that needed to be mitigated. The process included input from local historical societies, the Massachusetts Historic Commission, the State Historic Preservation Office and the Federal Highway Administration’s Advisory Council on Historic Preservation.

Design features also included details that were prevalent on the original bridge, such as the Massachusetts state seal, which adorns the portal bracing on the steel arches; a historic wall seal and bridge incorporation date, imprinted on the bridge’s concrete abutment; and stone bridge piers that replicate the granite design of the 1951 bridge.

Informative panels along the trail celebrate the lives of noted abolitionists John Greenleaf Whittier and William Lloyd Garrison, and include information about the local environment and the region’s transportation history.

Connecting the new bridge to its historic past, James Reid, a descendant of Whittier who participated in the dedication of the original bridge, attended the ribbon-cutting ceremony along with his grandson, Reid Jackson Langlois.

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.

By maintaining a uniform design and consistent details, the use of precast decks also resulted in a construction cost decrease for the project.

“The bridge is well-braced and efficiently uses structural steel,” Bertoulin said.

Each of the four arches features 40 cable hangers in a crisscross pattern, spaced at 12-foot intervals that provide additional support, creating a favorable distribution of stiffness and simple hanger connection details.

“A bicycle wheel offers a good analogy to the design of this bridge, where the lateral stiffness of the rim is larger than the stiffness in the direction of the spokes,” Bertoulin said.

Earlier this month, the Whittier Bridge/I-95 Improvement Project received the American Infrastructure magazine Bridge of the Year Project Award.

“It is an honor to have had the opportunity to work on a project that receives this recognition,” Bertoulin said. “WSP’s designers did an outstanding job of recognizing the needs of MassDOT and the desires of the community to create something special.”

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