Manchester Widens River Bridge

By Paul Fournier | September 28, 2010

A revitalized "Gateway To Downtown Manchester" is well on the way to completion as work crews recently passed the halfway mark on widening the Granite Street Bridge over the Merrimack River.

E.D. Swett Inc. of Concord, N.H., has a $9.2-million contract to widen the 470-foot bridge from four lanes to seven lanes, a key part of a $55-million project to build a new I-293 Exit 5 interchange and reconstruct Granite Street, a major arterial leading to Manchester center. The project, consisting of four contracts, involves unprecedented cooperation between the New Hampshire Department of Transportation and the city of Manchester.

"This is one of the most complex municipally managed projects ever undertaken in New Hampshire," said Roch D. Larochelle, P.E., senior project manager for CLD Consulting Engineers Inc. Based in Manchester, the firm is responsible for the design and construction administration of the city portion and prime consultant for the NHDOT on the design of the Exit 5 interchange. Dana Carlson, P.E., is the firm's engineer at the job site.

The project originally consisted of the NHDOT's reconstruction of Exit 5, but city officials realized that with the construction of a new full-access interchange there was a need to reconfigure and widen Granite Street from South Main Street on the west end to Elm Street on the east, including the river bridge. The new Exit 5 and improved Granite Street would not only provide direct access from the interstate to the popular Verizon Center civic complex, Fisher Cats (professional baseball team) Stadium and the Millyard business district, but encourage continued growth and development within the downtown area as well.

Larochelle explained that under the expanded plan, the city was responsible for planning and public participation, design, right-of-way and legal issues, utility coordination, permitting, and construction administration for its portion of the project, which includes the river bridge.

What's more, all of this work needed to be carefully coordinated and crafted to meet state and federal permitting requirements in hopes of receiving special earmarked funding for the project. In line with this, the city worked with local legislators and was successful in securing $15 million in funding for the Granite Street project as well as another $800,000 in railroad funding. This helped pay for almost two-thirds of the overall Granite Street project costs.

Swett's river bridge contract calls for the construction of a four-span structure with two new concrete abutments and three new concrete river piers. Framing consists of seven new built-up steel girders that will increase the bridge width from 69 feet to approximately 119 feet. Atop the girders will be 4-1/2-inch-thick, 8-foot by 7-foot precast concrete deck panels, covered in turn with 4 inches of cast-in-place concrete. Over this will be placed an asphalt membrane and 2 inches of bituminous concrete.

The contractor started work in August 2005, constructing a temporary work trestle on the upstream side of the existing bridge. According to Mike Cole, vice president, Swett crews under project superintendent Jeff Stilkey started out from the east end of the bridge and worked out into the river, driving battered steel piles — four to six piles per bent — into the river bottom to support the 315-foot-long trestle. Surplus steel beams from other bridge jobs were placed on the bents, and heavy oak timbers installed as decking over the beams. Swett walked its 110-ton capacity Link-Belt LS-218H crawler crane out on the trestle and began erecting the girders for the bridge addition.

While the trestle is a temporary structure, it's a sturdy one, having survived the area's raging floods of May 2006 when the Merrimack River, swollen by severe rainstorms, overtopped the deck by 4 feet according to Cole.

As work proceeded on the trestle, crews also drove sheetpile cofferdams to allow construction of the abutments and piers.

Cole pointed out that the bridge job requires nearly three-quarter million pounds of structural steel, supplied by fabricator Casco Bay Steel of Saco, Maine; and over 5,800 cubic yards of concrete, provided by Manchester Redimix Concrete Inc. of Manchester, N.H.

By June 4, construction of the bridge widening was more than 50-percent complete, according to CLD's Larochelle. Once the addition is finished, Swett will detour traffic to the new section and then begin replacing some 80 isolation bearings (bridge shoes) under the nine girders of the existing span. Job specifications call for completion of the bridge by May 30, 2008.

A second contract managed by the city, this one extending from the east end of the river bridge easterly to Elm Street, was awarded in late May 2007 to American Excavating Corp. of Derry, N.H. The $4.4-million contract includes Granite Street widening, traffic signal upgrades and a railroad at-grade crossing.

Two contracts totaling more than $40 million are being managed by NHDOT. At the west end of the project, Swett has an $11.8-million job calling for the demolition of several buildings, relocating utilities, reconstructing one local street and relocating another, and building a sound barrier wall and mechanically stabilized earth wall.

The other project managed by NHDOT, worth $28.7 million, is under way by Middlesex Corp. The Littleton, Mass.-based contractor is responsible for I-293 reconstruction including the highway bridge and ramp, and the reconstruction of the west end of Granite Street.

All contracts for this ambitious project, designed to improve highway safety, traffic flow and access to the city, and promote development of downtown Manchester, will be completed by November 2008.

(Ed.: In addition to key project personnel mentioned above, Dennis Anctil, P.E., represents the Manchester Department of Public Works, while Richard Robideaux, P.E., is the engineer for E.D. Swett Inc.)