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Supporting one of Canada's major transportation hubs.
The Canadian Pacific Railway (CPR) faced a challenge when creating a grade separation for trains and trucks heading in and out of their intermodal yard in Kleinberg, just 15 minutes north of Toronto's Pearson International Airport. The solution was a two-lane service road for trucks and an overpass for trains, all in the same yard. CPR chose engineered Super•Cor® steel structures to carry the loads of their heavy and frequent trains over the service road.
Challenges: extreme load, high water table, low height of cover.
The bridge, designed to withstand Cooper E-80 live loads, supports the total weight of the trains (5,350 tons) with ease. The design load presented by the trains is 4.2 times more severe than the Ontario highway design load. And Ontario has the heaviest highway design load in Canada. Coupled with the need for strength was a need to build the grade separation without disturbing the water table, which meant engineering two very strong bridges, each with a very low height of cover - only 1400 mm.
AIL flexibility helped keep the project on schedule and on budget.
While CPR knew that a concrete bridge might be an option, the initial bid from Atlantic Industries Ltd. (AIL) was more attractive. The field engineer for Hatch Mott MacDonald - CPR's contracted engineering firm - observed that the Super•Cor® bridges are performing as intended six months after installation. AIL engineer Scott MacRae acknowledges that AIL's initial quote, prior to confirmation of field geometry, was low.
"Our initial quote was for one 13.5-metre span, a 5.8-metre rise, and a 25-metre length with two to two-and-a-half metres of soil on top. When we were asked to respond to the actual tender, new rules needed to be applied to conform to the height restrictions and actual drawings, elevations, and field geometry for two bridges instead of one. To try to stick to our original budget, we recommended shortening the structures with vertical MSE Retaining Walls for headwalls. Despite all of the accommodations that needed to be made, the projects were finished on schedule. The assembly of the two structures began on July 18 and the track was open to train traffic on August 20."
The span of each structure was 15.6 m and the rise was 4.8 m. One of the bridges was 13.7 m long and the second, 25.9 metres. Like all Super•Cor®, the CPR bridges came in small, lightweight pieces that were easy to transport and assemble.
Encased Concrete Ribs added strength for extreme loading.
Reinforcing of Super•Cor® is not usually required; with such heavy loads, however, AIL's design required the ribs to be filled with concrete under the railway loading. The construction of the Super•Cor® bridges began with the casting of concrete footings for each structure. Once the footings were complete, the structure was assembled in place, arch pieces bolted together, and the Encased Concrete ribs poured in place. The finished product combines the lightweight and tensile strength of steel with the compressive strength of concrete. Contractors for the project were Warren Bitulithic and the installer was Atlantic Underground Services. For AIL, this installation was another world first. Never before had they placed a train on such a large structure.
The end treatment for the structures was wire wall, a welded wire mesh with a front face of 1219 mm x 610 mm. The MSE Retaining Walls provided a fast, flexible, and long-lasting solution.
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