The Relief Line subway project has long been a slow train coming down the tracks for Toronto commuters. The City of Toronto has proposed building such a line—in one form or another—since 1910.

A map from the November 25, 1911 Evening Telegram showing a streetcar subway along Queen and future connection along Pape. Image, Toronto Sun, Transit Toronto

Last week the project inched a bit further down the line toward reality when the Toronto Transit Commission's board of directors awarded a contract for designing the tunnels of the Relief Line South between Pape and Osgoode Stations. About the same time, Metrolinx, the TTC, and the City launched a website for the Relief Line North, a second phase to stretch northwards from Pape Station.

During its meeting of March 20, the commission awarded a contract for no more than $16M to Arup Canada to prepare the preliminary design of the tunnel and various other structures, including three crossings of other subway lines, substations, emergency exit buildings and underground cross-passages.

About six kilometres long, the Relief Line South will likely be entirely underground. The tunnel structures will pass directly under the Don River, the Don Valley Parkway, Line 2 once and Line 1 twice at three subway stations. In addition to the tunnels, the project also requires sections of cut-and-cover construction where the builders will launch and extract the tunnel boring machines.

Last May, City Council approved this alignment for the Relief Line South, image, City of Toronto

Arup will help confirm the tunnel configuration and construction methods through the city core. It will also help the TTC determine whether it should use a single or twin tunnel bore for the project.

During its meeting of July 12 to 16, 2016, City Council endorsed an alignment for the subway under Pape and Eastern Avenues and Queen Streets East and West. In May 2017, it gave the go-ahead to a revised route avoiding the residential area on Pape Avenue south of Gerrard Street East. The new path would curve westward near the GO Transit tracks between Pape and Carlaw Avenues and then southward to Eastern, with a station at Carlaw and Queen Street East.

The TTC's map of present and future transit lines. The asterisk marks lines whose routes and stations are not yet final, image, TTC

On February 15, 2017, City Council approved the TTC’s 2017-2026 capital budget, which includes $55.52M for preliminary design of the future subway line. The Province of Ontario has committed $150M to Metrolinx to work with the City and TTC to advance planning and designing the project. Metrolinx and the TTC are preparing a memorandum of understanding to define roles and responsibilities and to share the total costs of work required to develop the "class 3 cost estimate" for the project. Metrolinx has funded $45M for this preliminary design work.

Last November, the TTC issued a request for proposals to find proponents to "complete the Concept Design Report and Preliminary Design and Engineering for the Tunnels and associated facilities for the RLS, together with a cost estimate and project delivery schedule, to 30% design completion." Arup was the successful bidder for the contract.

Under this contract, Arup will advance the early design of the Relief Line South with the alignment that the City has previously approved to attain that cost estimate and schedule. When it has completed its work, probably in late 2019, the TTC can then present a report outlining the design and next-stage cost estimates for its board and City Council to approve. If both bodies approve the report, the project can advance to the next phase toward construction.

Meanwhile, work is starting on a following phase of the project, extending the line likely as far northward as Sheppard Avenue. Metrolinx is taking the lead on this project, with the TTC and City as its partners. The team has now established a Relief Line North website where the public can review its plans, which are still in early days.

The Metrolinx 2041 regional transit plan includes the Relief Line North and South projects, image, Metrolinx

The project team explains that "This continuation of the planned Relief Line South will help address a gap in our existing rapid transit network, offer alternative routes and relieve congestion on Line 1 Yonge and at existing and future interchange stations, including Bloor-Yonge and Eglinton-Yonge. Optimizing the transportation system ensures the best possible use of the existing and future assets and capacity. This means better connections to urban centres, employment nodes and regional destinations, and shorter, more comfortable commutes."

The future line will probably connect with the TTC's Line 5 (the Crosstown LRT, now under construction) at Science Centre Station and the Line 4 Sheppard subway at Don Mills Station.

The Relief Line North Project Team is working to identify the route alignment and station locations and begin conceptual design. One of several challenges the team has to consider is how and where the future line will cross the Don River Valley.

The Relief Line North study area, image, Metrolinx

The line supports the goals of the City's Official Plan and is an integral part of the Metrolinx 2041 Regional Transportation Plan. Provincial funding for the Relief Line North is in place to advance the planning and environmental assessment for the line.

The Relief Line South project team aims to start construction in 2025 and finish by 2031. A timeline for the Relief Line North project is not yet available.

What do you think of the plans? Share your comments in the form below, or join the discussion on our Forum.