On August 5, it was announced that Metrolinx has awarded a $4.32 billion contract to construct the easternmost tunnelled portion of Ontario Line 3, Toronto's first new downtown subway in over 50 years. Running under Pape Avenue between the Gerrard Tunnel Portal and the Minton Portal at the Don Valley, the twin 3-kilometre tunnels will also include two new underground stations at both Danforth and Cosburn avenues. 

Looking northwest over the intersection of Pape and Cosburn avenues, where two corners have been completely leveled to make way for Cosburn station, July 18, 2026, image courtesy of UrbanToronto forum contributor Kotsy

The contract, classified as a Target Price Agreement, comes after nearly four years of reviews and preliminary design work, a process that began when Metrolinx issued a Request for Qualifications for the "Pape Tunnel and Underground Stations" project in November 2022. 

By January 17, 2024, Metrolinx had selected Pape North Connect — a consortium including Webuild Civil Work Inc., Fomento de Construcciones y Contratas Canada Ltd., Arcadis, and AECOM — as the Development Partner. In the two years since, the teams have been advancing the design, costing, scheduling, and early works, a process dubbed a 'development phase' necessary to deliver East York's new subway.

A map of Ontario Line 3's routing, with the segment to be constructed as part of this contract highlighted in red, image courtesy of Metrolinx

These substantial preliminary works involved expropriating and demolishing large stretches of commercial and residential properties along the future subway's alignment to order to allow for complex subterranean works to commence, and the eventual construction of station entrances and emergency exits.

Looking north up Pape Avenue to where commercial and residential buildings once stood, since demolished to facilitate preliminary works on Cosburn station, July 12, 2026, image courtesy of UrbanToronto forum contributor flonicky

At the future site of Cosburn station, the station footprint will sit just to the west side of Pape Avenue, and as such, all buildings on the southwest and northwest corners of the intersection of Cosburn and Pape avenues have been cleared.

A diagram of under-construction Cosburn station, image courtesy of Metrolinx

Further south at the intersection of Pape and Danforth avenues, whole blocks of storefronts, houses, and apartment buildings have been levelled at the long-standing site of Pape station on Danforth Line 2. 

Looking north across Danforth Avenue on Christmas Day of 2025 following the major advancement of excavation on the site, image courtesy of UrbanToronto forum contributor Kotsy

This massive clearing is required to facilitate the complex surgery of constructing a new subway platform within the existing station, all while ensuring subway service continues uninterrupted.

A diagram of under-construction Pape station, image courtesy of Metrolinx

Work to excavate and reinforce multi-storey, below-grade tunnel boxes — which is already significantly underway at Pape station as seen above — can now proceed in its full scope with the aforementioned development phase complete. 

These underground structures will eventually be breached by massive twin tunnel boring machines. The launch shaft for these machines is currently being excavated at the former site of the Riverdale Shopping Centre, located at the northeast corner of Carlaw Avenue and Gerrard Street East. The aerial photograph below highlights the approximate routing Ontario Line 3 will take as it diverges from the shared GO Transit rail corridor to head beneath Pape Avenue.

Looking northeast over the Gerrard Portal, which will allow for the deployment of twin tunnel boring machines under Pape Avenue, August 3, 2026, image courtesy of UrbanToronto forum contributor Kotsy

It's worth nothing that while the execution of this Target Price Agreement marks a major milestone in the advancement of Toronto's rapid transit network, it comes at an extremely high price. Averaging out to nearly $1.5 billion per kilometre of subway track, this segment of Ontario Line 3 is on track to be one of the most expensive subway projects, not just in Canadian history, but world history, according to data from the Transit Costs Project. Additionally, many of the projects that exceed this venture in cost are vastly more complex. A prime example is New York City's Second Avenue Subway, which must navigate Manhattan's centuries-old labyrinth of utilities, active transit lines, and the deep foundations of countless high-rises that clog the island's subsurface. 

By comparison, the Pape Avenue portion of Ontario Line 3 will run directly beneath a corridor composed primarily of two to four-storey homes and commercial buildings. Interfacing with only one other subway line, it presents a comparatively straightforward delivery process. Despite this, the cost of Toronto's first new downtown subway in half a century continues to climb, with the initial 2019 estimate of $10.9 billion long since exceeded.

A rendering looking west over the intersection of Pape and Cosburn Avenues towards the future station head of Cosburn station, and planned mixed-use intensification, image courtesy of Metrolinx

UrbanToronto will continue to follow progress on Pape and Cosburn stations, and Ontario Line 3, but in the meantime, you can learn more about it from our Database file, linked below. If you'd like, you can join in on the conversation in the associated Project Forum thread 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.