REHABILITATION OF THREE BRIDGES AT LANSDOWNE AVENUE

摘要

In response to challenges created by Toronto's continued growth and increased transit needs, Amec Foster Wheeler's is committed to providing resilient solutions for replacing and rehabilitating Toronto's aging transit infrastructure. Amec Foster Wheeler incorporated these principles of sustainable design when they were retained by Metrolinx to complete the detailed design and construction supervision of the rehabilitation of three bridges carrying Metrolinx tracks over Lansdowne Avenue at Mile 3.12 Weston and Newmarket Subdivisions in Toronto, Ontario. A major component of the project is the replacement of two through plate girder spans carrying three tracks with three steel beam bridge spans seated on existing abutments. The proposed infrastructure for this location in the Metrolinx Georgetown Rail Corridor will include an eight-track corridor. Five new steel beam bridge spans were previously constructed at this location and are currently carrying five tracks with the remaining two TPG spans were replaced with the proposed three steel beam span bridges in April 2016. Each of the proposed new three bridge spans consist of four built-up steel plate I beams, 20.6 m single span and 4.24 m wide ballasted steel deck carrying one track. The spans are heavily skewed at 33.6o and will be seated on existing abutments. In order to compensate for the skewed span configuration, approach slabs were designed to be installed on the existing abutment ballast walls. The project also includes raising the existing track profiles to match the profile of adjacent tracks, utility relocations, and substructure concrete repairs. The constant and consistent rail traffic significantly limited the construction window to permit span replacements through available track blocks over two weekends only. In response to this challenge and to minimize the amount of work to be completed in the two weekend blocks, Amec Foster Wheeler's engineers devised that the bridge spans to be pre-assembled adjacent to the site and they were installed in one piece during the track blocks. Additionally, the existing ballast walls were modified by installing precast concrete sections complete with a seat for the new precast approach slabs. Further, the new bearings on steel grillage bearing seat assemblies were installed in order to raise the new beam spans and maintain the existing road clearance, with existing utilities relocated in advance of the proposed track blocks. Also, the existing bearing seats were leveled using a fast curing non-shrink, non-corrosive, non-metallic cementitious grout (Dayton Superior, Turbo Grout LT12). By utilizing these innovations Amec Foster Wheeler achieved the goal of rehabilitating this critical infrastructure asset, while at the same time ensuring minimal disruption to the essential rail traffic.