Construction Begins on Ontario Line 3 Elevated Guideway and Cosburn Station

NEWS CONSTRUCTION
February 18, 2026 by Anthony Teles   3.6K 

Construction Begins on Ontario Line 3 Elevated Guideway and Cosburn Station

Construction has officially begun on the Ontario Line 3’s elevated guideway and four new stations, another advance for the 15.6km rapid transit project. The three-kilometre structure from Thorncliffe Park to Eglinton and Don Mills will link new stations at Don Valley, Flemingdon Park, and Thorncliffe Park. Once complete, the 15-station line will run from Exhibition Place through downtown to Don Mills, where it will connect to the recently opened Eglinton Line 5.

Looking north to a rendering of Don Valley station and the elevated guideway, image by Metrolinx

The elevated segment will extend from the north end of the Don Valley Crossing Bridge at Overlea Boulevard in Thorncliffe Park — with another bridge, the West Don Valley Crossing, sandwiched between — and north to Don Valley station at Don Mills Road and Eglinton Avenue East, carrying trains on a guideway reaching up to 14m above grade. In this stretch alone, an estimated 30,500 residents would gain access to a subway station, while connectivity for 14,800 nearby jobs will also be improved. 

A high-angle rendering of Thorncliffe park station and the elevated guideway, image by Metrolinx

Ground has also been broken for Cosburn station, introducing a new rapid transit station serving the Pape Village area and improving commute times for more than 10,000 residents in this area of East York. Across the full alignment, the Ontario Line 3 will provide more than 40 connections to local and regional transit. 

Looking southeast to Cosburn station, image by UrbanToronto Forum contributor TrianglesOnTheWall

Travel times are projected to drop sharply, including a reduction from 40 minutes to 25 minutes between Thorncliffe Park and downtown, and from 25 minutes to 12 minutes between Pape and Danforth and Queen and University. The line is also anticipated to ease pressure on the existing network, reducing peak-hour crowding at Bloor–Yonge station by up to 22 per cent, and cutting congestion by up to 15 per cent on the busiest stretch of Line 1 between Bloor and Wellesley.

“This new line will bring more people within walking distance of transit, reduce congestion on our roads, and make daily commutes shorter for families and workers,” noted Mayor Olivia Chow. “As Mayor, I am committed to keeping the TTC affordable by freezing fares for three years while increasing service and improving reliability. We are also introducing fare capping this year so Torontonians can ride more and pay less.”

The growing excavation for Ontario Line 3 at Pape station, image by UrbanToronto Forum contributor kotsy

Work on the elevated guideway builds on several milestones already underway along the corridor. In October, 2024, crews began constructing the two new bridges spanning the Don Valley, while excavation commenced at Pape station in July, 2024. There, approximately 20 per cent of the site has now been dug out, with roughly 24,000m³ of soil removed to date. 

“With work underway at all Ontario Line stations south of Bloor-Danforth, and iconic bridges being built over the Don River, we are delighted to begin construction of the four northern stations, which will put more than 40,000 residents within walking distance of this incredible project,” said Michael Lindsay, President and CEO of Metrolinx.

A drone view of the West Don Crossing, image by UrbanToronto Forum contributor kotsy

Queen’s Park is covering more than 80 per cent of the project’s capital construction costs, with the Government of Canada contributing over $4 billion. The line is one of four priority subway initiatives advancing under the Transportation Plan for the Greater Golden Horseshoe, alongside the Danforth Line 2 Scarborough Subway Extension, the Eglinton Line 5 Crosstown West Extension, and the Yonge Line 1 North Subway Extension.

“Once complete, the new Ontario Line will revolutionize travel across the Greater Toronto Area, reducing gridlock on our roads and highways and improving travel within the City of Toronto,” shared Todd McCarthy, Acting Minister of Infrastructure. “As part of our government’s more than $220 billion capital plan to protect Ontario, we are building transit-oriented communities along several priority subway stops, including at Thorncliffe Park and Cosburn stations on the new Ontario Line.”

Looking from Flemingdon Park station along the guideway towards Don Valley station, Metrolinx

Across the full corridor, Ontario Line 3 is projected to support nearly 390,000 daily boardings and bring nearly 230,000 additional residents within walking distance of rapid transit. During construction, the project is expected to sustain approximately 4,700 jobs each year. It is anticipated to reduce daily car trips by at least 28,000 and greenhouse gas emissions by 14,000 tonnes annually.

UrbanToronto will continue to follow progress on these developments, but in the meantime, you can learn more about them from our Database files, linked below. If you’d like, you can join in on the conversations in the associated Project Forum threads or leave a comment in the space provided on this page.

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UrbanToronto’s research and data service, UTPro, provides comprehensive data on construction projects in the Greater Golden Horseshoe—from proposal through to completion. Other services include Instant Reports, downloadable snapshots based on location, and a daily subscription newsletter, New Development Insider, that tracks projects from initial application.​