This week, UrbanToronto got an inside look at the construction of the future Eglinton Station, where the Crosstown LRT will intersect with Line 1's Eglinton Subway Station. Metrolinx officials spoke about the challenges of building this particular station, specifically the underpinning of the existing subway infrastructure.
Crosslinx Transit Solutions President Bill Henry led a tour of the station site, noting that 6 of the new Bombardier Flexity trains that will ply the line have already been delivered to the Eglinton Maintenance & Storage Facility at Mount Dennis Station for testing. He also stated that track installation is well underway, particularly in the east end, where the trains will make stops at-grade.
Construction of Eglinton Station itself is a massive undertaking. The 269 metre-long and 17 metre-wide station 'box' began excavation in December 2018, with roughly 80 dump trucks of soil leaving the site every day. In that time period, over 1,000 shoring pins have been installed on the walls of the excavation, as well as the overhead infrastructure supporting Eglinton Avenue above. Pictured below is a panorama of the west cavern, with the east portion—just on the other side of the Yonge Subway Line—almost double the size. The excavation is currently at about 40-50% of its completion depth.
Between the two massive caverns, meticulous work is being done to create a support structure for the existing subway line, which is crucial for this interchange station to operate. Metrolinx has set out the requirement that the underpinning of Line 1 must be constructed without any interruption to TTC Subway service, and that the existing infrastructure shift no more that 3 millimetres. Crosslinx is aiming for no more than a 2 millimetre shift as a result of this process. For reference, the margin for success is roughly the width of a grain of rice. Henry stressed that despite the complexity of the process, similar feats have been achieved all over the world. Two shots below give a closer look at activity in the west cavern.
The entire underpinning process, already underway, is projected to take a total of 16 weeks. First, 6 support caissons are drilled 40 metres down, with three on each side straddling Line 1. Two large steel girders will then run north-south, connecting the caissons together. Following this, a small remotely-controlled excavator will dig 5 'gallery' tunnels underneath the subway line to connect the two rows of caissons. Needle beams with be 'threaded' through the galleries, connecting to the two steel girders and creating the final support structure for the track above. Temporary hydraulic jacks will be installed throughout this entire process to offset any slight changes in elevation, and act as a fail-safe mechanism during construction. The animation below, provided by Metrolinx, gives a visual overview of this entire process.
A similar process is taking place at Eglinton West Station, soon to be renamed Cedarvale. Despite the incredible engineering complexities here, the Crosstown is still on schedule for a September 2021 opening.
You can see images of what Eglinton Crosstown station should look like when completed, in our database file, linked below. You can get in on the conversation in the associated Forum thread, or leave a comment in the field provided on this page.
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