• More Patches than a Vagabond's Britches

    005.by Joseph A. Parzych

    On May 19, 1937, Daniel O’Connell & Sons of Holyoke won the contract to build a 30-foot wide bridge from Turners Falls to Gill, Massachusetts. It would include a 5-1/2 foot wide sidewalk and the length of the bridge would be approximately 2,200 feet. It was designed to rest on five piers, crossing the Connecticut River, and the cost for the entire project would run approximately one million dollars. Work began on May 24, 1937 and it was dedicated on September 10, 1938.
    Over time, due to the wear and tear of daily traffic, a “speed bump” had developed on the Turners Falls side. It gradually developed over the years as the supporting steel beams underneath, rusted and rotted away from the ravages of age, spray from the nearby dam, plugged drains, and ice control chemicals. Not only had the ends of the beams become eaten away, allowing the bridge to sag, but the concrete piers supporting them showed signs of deterioration as well.

    While the Turners Falls-Gill Bridge is not an exact replica of the Minneapolis truss bridge that collapsed just a few years ago, it is a truss bridge of similar design. They both were built with concrete decks susceptible to road chemicals that eat away at both the concrete and supporting steel. It is because of this deterioration that the bridge beams beneath the deck were reduced to little more than lace, while the travel surface required multiple patches. The surface looked like it “Had more patches than a vagabond’s britches.” Shockingly, holes two feet across opened up providing a view of the Connecticut River flowing below.

    The Turners Falls-Gill Bridge project encompassed work on three bridges. These included the Turners Falls-Gill Bridge with one-way traffic coming into Turners Falls. The other two, the General Pierce Bridge and the Seventh Street Bridge were to be used to exit the town but because they were in poor shape and weight restricted. Before the TF-Gill Bridge rehab could begin, General Contractor, SPS New England of Salisbury, Ma, needed to repair the General Pierce Bridge sufficiently so that it could withstand trucks carrying heavy loads. Once that was completed, SPS performed remedial work on the Seventh Street Bridge that lifted weight restrictions there as well. This all took place during work on the Turners Falls-Gill Bridge.

    Initially, SPS or their subcontractors worked around the clock remediating the Seventh Street Bridge to lift weight restrictions. They closed the bridge at night to do their work when trucks did not need to access a paper mill on the other side. Mimosa, a subcontractor, installed suspended scaffolding under all three bridges. Meanwhile, Atlantic Bridge and Engineering, who worked on all three bridges as a subcontractor, repaired or replaced deteriorated beams on the Seventh St Bridge, here again, largely during the night. SPS subbed out the construction of staging and the airtight enclosure of the bridge that was need to do lead paint shot blasting removal from the structure. When that was completed, the structure was recoated with zinc chromate primer, epoxy paint and urethane.
    During the project, while removing old beams and placing new beams for a cantilevered extension of the bridge’s foot traffic, SPS closed the bridge at night, to do the work. The new, cantilevered sidewalk widened the traveled way from its original 30 feet, to a width of 33 feet. That included the 5.5 ft cantilevered sidewalk projecting out over the river.

    As a part of the project, the bridge needs to be jacked up enough to replace and reverse its wear plates. As incredible as it sounds, the plan to accomplish this is to use 50-ton capacity; hand operated hydraulic jacks to lift the bridge. Since the bridge is flexible, the entire structure does not need to be raised. A portion at the end of the bridge will flex enough for one man to raise the bridge the ¼ of an inch or so that is needed to relieve the pressure on the plates and allow them to be removed and replaced in reverse order. Because the extremes of daily outdoor temperatures affect the length of the bridge, the job of jacking up the bridge, reversing the plates, and replacing its lubricant and seals must take place during a period when the mean temperature is 50 degrees Fahrenheit. In this case, that will be sometime in October of 2013.

    One of the more impressive feats of engineering on this job, was the installation of cantilevered beams, replacement beams, and five inch thick, sections of bridge deck, all prefabricated by subcontractor Atlantic Bridge & Engineering of Salisbury, MA, This was done in their Nottingham, NH, shop.

    Engineers took measurements with a 3-D laser and with conventional tape measures, before feeding the results into a CAD program that produced detailed prints for the beams and decking. Atlantic Bridge & Engineers then fabricated beams and bridge deck sections at their Nottingham, NH, facility. When the components arrived at the Turners Falls-Gill Bridge, they fit into place, like pieces of a jigsaw puzzle.

    The new sections mounted over anchor studs previously welded to the top flange of the existing I-beams. Replacement beams, and beams for the cantilevered sidewalk were also cut and predrilled with holes to match the rivet holes in existing beams. Three quarter inch galvanized high tensile strength bolts, one and one quarter inch long, replaced the original rivets. Ironworkers tightened the nuts using torque wrenches set to a fraction over 300 foot-pounds of torque.

    In order for the new, cantilevered sidewalk to go around the existing art deco abutments, SPS employees constructed corbels anchored with eight 1″ re-bar sections each 20″ long. These were cemented into holes drilled into the existing abutments to support a balcony-like structure. The result is very attractive platform with a concrete railing, making it suitable for viewing the Turners Falls Dam. The $40 million bridge project heading toward completion, which is scheduled for sometime in 2014.

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