Contractor Wyman & Simpson Inc. recently completed building a replacement for an 88-year-old bridge over the Androscogin River between Peru and Mexico, two small towns in southwestern Maine. The new Bridge 2019 was dedicated on October 26, 2018, to Private 1st Class Buddy McLain of Mexico, a cavalry scout with the U.S. 101st Airborne Division, who was killed in Afghanistan on November 29, 2010.
Built in 1930 as the Great Depression began crushing the U.S. economy, Maine Bridge No. 2019 has survived the often tempestuous flows of Maine’s third largest river – a 170-mile-long watercourse draining more than 2,300 square miles marked by numerous rapids and waterfalls. Located on North Main Street, the old river bridge was designed as a triple-span, riveted Parker through-truss with the roadbed supported by the bottom chords. It succeeded atrussed four-span iron toll bridge built 35 years earlier to replace a ferry that had operated for decades in the area.
A Disappearing Breed
Truss bridges such as Bridge 2019 are one of the oldest types of modern bridges, and are economical to build because they use materials efficiently.Iron truss bridges had started appearing in the U.S. in the 1870s but by the 1890s were already being supplanted by steel trusses when the iron Mexico-Peru Bridge was completed in 1895. Steel truss bridges were commonly constructed from the 1890s through the 1930s. Their numbers are dwindling now as they outlive their useful service life and are being replaced mainly by bridges designed with steel girders, concrete decks, and substructures. In general, steel girders are typically I-beams made up from separate structural steel plates, rather than being rolled as single cross-sections, and are welded or, in the case of earlier plate girders, bolted or riveted together to form the vertical web and horizontal flanges of the beam.
Oriented from north to south, the existing trussed Peru-Mexico Bridge is positioned on North Main Street between Route 108 in Peru and Route 2 in Mexico. Measuring 574 feet in length, the triple-span bridge has a roadway width of about 23 feet, providing two 11-foot-wide traffic lanes. A 5-foot-wide sidewalk is hung from cantilevered brackets attached to the outside of the truss.
Its substructure consists of north and south abutments supported by mass, cast-in-place concrete footings constructed on bedrock, and two cast-in-place reinforced concrete piers on piles driven to bedrock. An existing set of tracks operated by Pan Am Railways (formerly Maine Central Railroad) cross the southern bridge approach roadway about 200 feet south of the south abutment.
A number of different repairs and modifications have taken place on the existing bridge over the years, but the Maine Department of Transportation officials have been increasingly concerned about the deteriorating condition of Bridge 2019. The structure has seen its sufficiency rating slip from about 43 out of a possible 100 in 1997, to only 6 in 2015.Structural appraisals classified the bridge as deficient due to the poor condition of the truss and floor system, and labelled the bridge condition as “basically intolerable requiring high priority of replacement.”
Maine DOT posted the bridge for 25 tons in 2013. A detailed “rehabilitation or replacement” study was performed that recommended complete replacement of the bridge. Engineers undertook the final detailed design process in 2015, and Richmond, Maine, contractor Wyman & Simpson started construction in January 2017 under a $7.7 million contract with Maine DOT.
Anticipated financing for the project was assured by the inclusion of $11.1 million for the bridge project in Maine DOT’s Work Plan for Calendar Years 2015 through 2017. This program involves 523 proposed capital projects with a combined total value of $469 million – among them, the replacement or rehabilitation of 47 bridges with a total estimated value of $95 million.
Longer and Wider
Resident Engineer Catherine Mettey, P.E. represents Maine DOT on the bridge construction site, while Runar Schlosser is the Project Superintendent for Wyman & Simpson.
Longer and wider than its predecessor, the new 600-foot-long by 43-foot-wide bridge is situated parallel to, and immediately downstream from, the old existing structure. It relies not on trusses, but on five deep weathering steel plate girders spaced 9-feet, 5-inches center-to-center to support the bridge. These haunched girders extend over two massive concrete piers, creating three spans of 185 feet, 230 feet, and 185 feet, respectively. Girder haunches were fabricated using varying depth steel plate for webs (60-inch to 96-inch), and are deepest at the piers where stresses are greatest due to negative bending moments.
The 8-inch-thick deck is a composite of 4-inch precast deck panels overlaid with 4 inches of cast-in-place concrete. The 32-foot-wide, asphalt paved roadway deck provides two 11-foot travel lanes and two 5-foot shoulders. An 8-foot-wide, raised concrete sidewalk is constructed on the upstream side of the new bridge to accommodate pedestrians and recreational travel modes.
Raising the Railroad
In addition to new bridge construction, the project upgrades more than 2,000 feet of paved approach roadway along North Main Street and U.S. Route 2, including the replacement of an existing at-grade crossing of the Pan Am Railways track. The latter required the bridge to be closed for about a week, necessitating an 8-1/2 mile detour so workers could raise railroad tracks, according to Mettey. She indicated that approximately 800 feet of track on each side of the crossing had to be raised, gradually sloping upward to meet the 2-foot higher roadway elevation. This happened early in the construction process so that railroad crossing signals could be installed, thus allowing an at-grade crossing to be opened in the construction zone – a federal requirement.
Above the Highest Flood
The new bridge is designed to provide clearance above the highest river elevation in history for the area, as recorded by a U.S. Geological Survey river gage in nearby Rumford. This happened in 1936 when a 500-year storm caused a catastrophic flood with a maximum river flow of 80,745 cubic feet per second (cfs) and a peak elevation of approximately 417 feet above sea level. This compares with an ordinary 1.1-year high water flow of 18,963 cfs and an elevation of approximately 403 feet.
According to Mettey, once the new bridge is officially completed, the existing bridge is slated for removal by, and becomes the property of, contractor Wyman & Simpson. Bridge removal pertains to the entire superstructure plus pier caps, pier columns, and portions of abutments and retaining walls. Specifically, Wyman & Simpson has to cut down the existing south abutment to a minimum of 3 feet below proposed grade; existing piers to a minimum of 1 foot below the streambed; and the north abutment to a minimum of 1 foot above the proposed grade.
Mettey noted that the project started on December 19, 2016, and was completed in time for the dedication ceremonies in October 2018.
“During this time the contractors placed about 3,300 cubic yards of concrete, tied in about 160,000 pounds of rebar, and erected 1.25 million pounds of structural steel,” she said. “Wyman & Simpson, Inc. was not only the general contractor but also self-performed the structural steel erection and project earthwork.”
Dedication to a Young Soldier
The new bridge was officially dedicated as the PFC Buddy W. McLain Memorial Bridge on October 26, 2018. Buddy McLain of Mexico was a cavalry scout with the U.S. Army's 2nd Squadron, 61st Cavalry, 4th Brigade Combat Team, 101st Airborne Division.
He deployed from Fort Campbell, Kentucky, to Afghanistan on August 24, 2010, leaving behind his wife Chelsea and infant son Owen. It was Owen’s first birthday.
McLain was killed in Afghanistan a few months later, on November 29, 2010. He was 24.
At the bridge dedication, Owen, now nine years old, unveiled the plaque dedicating the bridge to his father. After the ceremony, Owen was driven in a Mexico Police cruiser over the bridge – the first vehicle to cross the span.
Major subcontractors and materials suppliers for this project include:
Photos and sidebar courtesy of Maine DOT Resident Engineer Catherine Mettey, P.E.
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