The GTA is in the midst of an infrastructure blitz. New roads, bridges, buildings, sewers and cables are being built all around us as the region's population swells. To make sure everybody can get around, Metrolinx is putting into action its $50 billion Big Move transit infrastructure program. Upgrading the GO Transit network's rail backbone is one of the most important parts.

Georgetown South Corridor current and future tracking, image courtesy of Metrolinx

In west Toronto, the Georgetown South Project is seeing new tracks, stations, bridges and underpasses being constructed in advance of the 2015 Pan Am Games. The West Toronto Diamond Grade Separation is one of the most complex pieces of the project and in many ways a marvel of engineering and planning.

West Toronto Diamond with preliminary project work, image courtesy of Metrolinx

A few steps away from the Keele Street and Dundas West intersection is Canada's busiest rail intersection. Here at the West Toronto Diamond, 5 train lines including VIA Rail meet each other. Heading North-South, GO Transit's Georgetown line and a CN Freight line meet at grade with the East-West GO Milton line and the CP main freight corridor through the city.

Current Configuration of West Toronto Diamond, image courtesy of Metrolinx

Final Configuration of West Toronto Diamond, image courtesy of Metrolinx

The at grade crossing has worked for years, but with GO Transit increasing its service and with the upcoming addition of Union-Pearson Express train service, delays due to rail traffic would become unacceptable. To overcome that, the project will see all north-south traffic pass below the east-west CP line in a new underpass. Thanks to Forum member drum118 and his technical and photographic expertise, UrbanToronto can break down the several steps involved in the project.

Underpass and the diverted Georgetown tracks at the West Toronto Diamond, image courtesy of drum118

With high rail traffic on both corridors, Metrolinx and the railway companies agreed that extended periods of down time for construction were not possible: the trains must keep moving. The logistics, combined with intricate planning, massive engineering, and work scheduling necessarily made what was already a massive job into something extraordinary.

Crews began over the past few years by realigning the tracks and drilling over 2,300 piles for the future underpass walls as shown above. New tracks for the Georgetown corridor will next be regraded from Dupont Street to St. Clair Avenue West to provide a shallow entry and exit into the new underpass.

Lowered grading into the underpass looking south, image courtesy of drum118

With extended delays to CP's freight operations impossible, the lengthy process of demolishing the old crossing and building a new new bridge in-situ was not an option. Instead, Metrolinx opted to slide a new bridge into place over the old at-grade crossing location on Labour Day weekend.

Steel plate guidance system for sliding bridge deck, image by drum118

A steel guide track for the sliding plates, shown above, was installed over top the concrete underpass retaining walls. The pre-constructed bridge span was then put into place on the guide rails adjacent to the CP tracks. In the early morning around 5AM the last freight train cleared the CP tracks and crews were able to start the heavy move into the final location. To push the 900 metric ton bridge span into place, two massive computer synchronized hydraulic jacks, shown below, were used.

Tandem Hydrolic Jacks used to slide the bridge deck into place, image by drum118

First, workers removed the CP tracks and rock ballast materials from the temporary supports, as show below in one of drum118's many videos of the project.

Next the steel and concrete retainers were cut out and removed to allow the new span to slide in. Workers here had to make several unexpected cuts to get all the material out, adding delay to a tight schedule.

Temporary concrete liners removed before bridge span pushed into place, image by drum118

The bridge deck was then pushed into place by the jacks. Once in place the surrounding sections were back-filled with ballast so the CP tracks could be reinstalled across the new decking. In the video below released by Metrolinx, the whole operation comes to life and you can really appreciate the amount of work involved in such a tight window.

The push lasted about two and a half hours, and the whole operation took place and breakneck speed over 24 hours. Below is a final before-and-after, comparing the old temporary wooden CP track section with the newly installed bridge deck.

Old:

Old temporary CP rail spans, image by drum118

Bridge deck in its final location just before track reinstallation, image by drum118

Trains still cross at grade at a temporary location hinted at at the bottom of the photo above, but when the underpass goes into service in 2014, the familiar clickity-clack of trains crossing tracks that has come to define the intersection for 131 years will be no more. This isn't the end of the West Toronto Diamond Grade Separation though. Crews still need to finish the tunnel tracks and fit in another bridge, steps away at Old Weston Road. Metrolinx will keep busy with the remaining work on the Georgetown South Project but can rest easy now that the Little Big Move is complete.

As Metrolinx continues its push to provide better transit throughout the region, UrbanToronto will keep you up-to-date with the latest headlines and details. Join our extensive Forum discussion here, or leave a comment below to have your say on this significant GTS milestone. For more Georgetown South Project information checkout the official website.