When the Ontario Line was announced in April, 2019, there were a wide range of reactions among the transit passionate in Toronto; some groaned at the prospect of yet another plan being changed, while others were excited at the prospect of a much expanded project. 

Three years since the announcement, signs of the project’s progress are visible; for better or for worse, the long needed downtown relief line (albeit by another name) is closer than it’s ever been to actually being realized. With new renderings of the potential look and feel of the Ontario Line stations released recently, it’s worth taking a look over everything we know about this project, likely the largest urban subway currently being executed in North America.

The Relief Line South

Relief Line South Map, image courtesy of the City of Toronto

The natural starting point for the Ontario Line is the Relief Line South, its slightly worse named predecessor. Either way, a “relief line” has been a long identified need in Toronto’s subway network, intended to provide a second route between the eastern portion of Line 2 and the downtown core; this plays the dual roles of eliminating extreme crowding at Bloor Yonge Station — which was (probably foolishly) never designed for such major transfer volumes — and reducing heavy crowding on the Yonge portion of Line 1 for much of its length. 

The Relief Line South was to be an 8 stop line connecting from Pape Station on Line 2 to Queen and Osgoode Stations on Line 1, via Pape, Carlaw, and Eastern avenues, and Queen Street. The line was planned to be entirely underground, including a deep crossing below the Don River. It would have connected to the existing subway network most likely via Greenwood Yard (though a wye at Danforth was conceivable, it seemed unlikely due to its complexity, and would have been redundant). The Greenwood Yard currently serves Line 2, but would in all likelihood have been transferred to serve the Relief Line after being rebuilt to accommodate long single unit trains (as opposed to the subdividable trains currently in use on Line 2). Line 2 would first have needed to have a new yard built at its western end where space has already been acquired, and which is likely necessary nonetheless for the expanded subway fleet needed after CBTC signalling installation and the extension east to Scarborough (as well as providing storage space for more modern single unit trains used on lines 1 and 4).

The connection between the subway lines would not be new for Toronto: Lines 1, 2, and 4 are all currently connected, and equipment can travel between them via connecting tunnels. That said, using the Greenwood Yard for the Relief Line would have restricted it to using the same loading gauge and power feed type as the existing lines, and so the Relief Line South was designed as such, using specifications intercompatible with trains from the existing subway network.


The Ontario Line

Ontario Line Map, image courtesy of Metrolinx

The most notable differences between the Ontario Line and the Relief Line South are its expanded scope and altered alignment. Instead of terminating at Osgoode to the west, the Ontario Line is to continue further west to serve Queen and Spadina before dipping south to serve King and Bathurst, and then terminate south of Liberty Village at a massively expanded Exhibition Station.

Looking east to Exhibition Station, image by HDR Architects for Metrolinx

At the same time, instead of the line terminating at Pape at its northern end, tunnels will continue northwards to serve a station at Cosburn and Pape and then further to a portal above the Don Valley Parkway.

Taking a pause, these extended tunnels are a fairly big deal; tunnelling through such dense parts of Toronto is likely to be complex and disruptive as years of construction on Eglinton Avenue has shown us. Extending the tunnels to logical surfacing points means getting the hard tunnelling done in the initial project rather than later, which may well make future extensions more palatable. By comparison, the Relief Line South plan would have required tunnelling to continue west from Osgoode and north from Pape for extensions, which would require opening up new tunnelling staging sites and creating significant disruption in these areas once again, likely to be very unpopular.

Now, the Ontario Line does not simply end over the DVP, instead it crosses the Don Valley on a new bridge and serves the densely populated but poorly connected neighbourhoods of Thorncliffe Park and Flemingdon Park, before terminating at Science Centre Station, currently under construction for Line 5, the Crosstown LRT. This whole portion of the Ontario Line would be elevated on a nice elevated structure akin to the Vancouver SkyTrain.

Flemingdon Park Station, image by HDR Architects for Metrolinx

Of course, quite notably, the eastern section of the Ontario Line is also different from the Relief Line South. Rather than tunnelling deep under mostly single family housing in Leslieville and Riverside, the Ontario Line will mostly use extra Metrolinx-owned space which already exists in the Lakeshore East GO train right of way, which is already being widened from three to four tracks as part of the GO Expansion project. This will in theory reduce the cost of the project by enabling several previously underground stations to exist on the surface, while enabling much more convenient transfers between massively expanded GO services and the subway, a far cry from the significant vertical ascent needed at a station like Downsview Park, where a similarly deep-tunnelled subway line meets a surface GO line.

Gerrard Station, image by HDR Architects for Metrolinx

The Ontario Line will rise above ground beside an expanded GO rail corridor at Pape Avenue, before continuing along it until crossing the Don River above ground and then transitioning back underground to serve a station at Corktown, west of the Distillery District, and then returning to the original alignment under Queen Street.

Overall, the new alignment being planned by Metrolinx is clearly designed to better integrate with Metrolinx’s other priority projects — most notably GO Expansion — by meeting and allowing for GO transfers both west and east of Downtown Toronto, something which some have suggested may aid in reducing crowding at Union Station. At the same time, the elevated northern terminus and surface western terminus should aid in making future extensions (particularly north to relieve more of the Yonge Line) less costly. While more stations west and east of Downtown will also help serve massive redevelopment in areas like the West Don Lands, Port Lands, King and Queen West, and Liberty Village, some commentators have suggested the lack of a station at Cherry Street is a major missed opportunity.

The northern extension to Eglinton will start to relieve the Yonge Line north of Bloor Street, but a further extension of the Ontario Line to Sheppard would also help to mitigate crowding on the Yonge Line from the Crosstown LRT, as well as crowding on the Crosstown itself, which may well become crowded at Science Centre, a station which will not receive the same service as western stations on the line, but which will serve the very busy Don Mills and Lawrence East buses.

Science Centre Station Under Construction, image by Reece Martin

Of course, putting rail at or above the surface has ruffled feathers among neighbours who would have preferred a subway line — out of sight and out of mind — despite the massive connectivity improvements that the Ontario Line’s east end vertical alignment will bring, and even though the rail corridor through the east end has been there for over 100 years now. Unfortunately, the passionate voices in the East End have somewhat drowned out voices in Thorncliffe Park where the community is conflicted on the presence of a maintenance and storage facility on the north side of the neighbourhood which would require the relocation of a number of community staples, including a mosque, in the ethnically diverse neighbourhood. Fortunately, well organized advocacy seems to have ensured that Metrolinx will assist both small businesses as well as the mosque in being relocated, while the lands adjacent to the longstanding North Toronto freight line and hydro one transmission corridor will be used for train storage and maintenance.

Thorncliffe Park Station, image by HDR Architects for Metrolinx

We will be back soon to talk about more of what we know of the Ontario Line so far in Part 2.

You can learn more from our Database files for the project's stations, linked below. If you'd like, you can join in on the conversation in our dedicated Ontario Line Forum thread, or leave a comment in the space provided on this page.

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