davenport diamond metrolinx

Here's how a new elevated rail line is being built through Toronto

Toronto is in the midst of an infrastructure glow-up unlike anything in a generation, with several significant transit investments unfolding across the city.

Subway and light rail lines get most of the attention, but the GO Transit rail system linking the city and surrounding municipalities is also undergoing a generational transformation that will increase capacity and service for the network.

One choke point that has limited the system's expansion for years is the Davenport Diamond, the intersection where the Barrie GO corridor meets the CP rail tracks.

GO and VIA passenger trains traversing the diamond are forced to fight for space with CP freight trains on one of the busiest train intersections in North America.

Metrolinx and Infrastructure Ontario are building an elevated guideway and flyover through the Junction Triangle, Wallace Emerson and Brockton Village neighbourhoods to relieve congestion at the at-grade rail intersection.

By allowing passenger trains to fly over the freight tracks unobstructed, the new elevated guideway will ease a bottleneck that impedes GO Transit's promise to implement all-day, two-way service on the Barrie GO corridor.

Construction of the guideway was tasked to Graham Commuter Rail Solutions, and work has been making noticeable gains in the time since a temporary diversion track was completed in September 2020.

Many are familiar with the rolling road closures and construction noise associated with the project, but behind all the noise and detours, there are some pretty fascinating methods in play to make the new guideway a reality.

A series of photos shared on Twitter offers a unique perspective overlooking the guideway's ongoing construction, and a glimpse into how the new elevated rail line is assembled from prefabricated concrete girders.

Described by engineers Hatch as a "precast and post-tensioned side-by-side double-voided box girder guideway structure," the guideway's girders are fabricated off-site and transported to the build area.

The process starts with concrete piers poured to support the elevated structure. Girders are then lifted into place using mobile gantry cranes placed on steel beams, in a setup allowing the cranes to slide along to the next lift site after hoisting a section of the guideway.

Images of the assembly reveal that as a section of girders is hoisted into place, crews are already working ahead at the next set of piers installing steel support for the gantry crane's next forward movement.

This moving, modular construction method allows for the installation of a new section every 36 hours or so.

GO Transit will get a shining new piece of infrastructure to better move trains through the city, while the neighbourhoods the guideway passes through will be getting new public space below the tracks, reuniting neighbourhoods that have been severed by rail lines for generations.

Trains will zip along the new guideway as early as 2023, opening up the door for GO's next round of transit enhancement.

Lead photo by


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