Metrolinx has announced the start of major construction work on the new Lower Don Bridge that will carry Ontario Line trains across the Don River between the Corktown and Riverside communities.

In 2023, construction crews cleared the area, relocated a watermain that went beneath the railway, and shifted the existing train tracks. The work was completed to prepare the site for the start of bridge construction.

The tracks needed to be shifted because the Ontario Line will run alongside GO Trains in the shared rail corridor in the area. Shifting the tracks makes it possible for continued GO service during Ontario Line construction and makes space for new Ontario Line tracks.

With the site now cleared and utilities moved to a new spot, construction on the new bridge’s east support structure is starting with installation of two concrete and steel piers that will support the foundation of the bridge. Once the east side is completed, crews will move to the west support structure.

The new bridge will be built north of the existing Lower Don Bridge over the Don Valley Parkway and the Don River.

Design work on the project is being run by HDR Inc.

The new structure will be a steel network tied arch, carrying two tracks over the Don River and Don Valley Parkway. The span length will be 120 metres with an out-to-out width of 13.7 metres. The maximum height of the arch, centre to centre, is 24 metres.

The Ontario Line subway is expected see nearly 400,000 daily boardings and will reduce major crowding at the existing Union and Bloor-Yonge subway stations by up to 14 and 22 percent, respectively.

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