Tunnelling for Scarborough Subway Gets Underway With ‘Diggy Scardust’

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Tunnelling for Scarborough Subway Gets Underway With 'Diggy Scardust'

One of the many myths about the late Toronto Mayor Rob Ford is that he would sing “subways, subways, subways” whenever anyone asked him about the future of mass transit in Scarborough. Now, however, the Scarborough Tube dream is becoming a reality, according to recent Metrolinx news.

Scarborough Subway project map, image courtesy Metrolinx

The provincial transportation authority recently announced that its contractor has commissioned a tunnel boring machine (or “TBM”) nicknamed Diggy Scardust from a site near Sheppard Avenue East and McCowan Road, marking a major milestone for the Scarborough Subway Extension”. This project, one of four announced by the late Mayor’s brother, Ontario Premier Doug Ford, in April 2018, extends the TTC’s Danforth Line 2 subway northeast beyond the current Kennedy Terminal, serving three stations deeper into the eastern suburbs of Toronto.

A closer look at the TBM in the launch shaft near Sheppard Avenue East and McCowan Road as it begins digging, image courtesy Metrolinx

Over the next two years, the TBM will travel 10 to 15 meters per day, moving south from the launch shaft location toward Eglinton Avenue East and Midland Avenue. It will dig around 6.9 kilometers of the 7.8-kilometer tunnel for the future subway. Unlike most of Toronto’s recent transit tunnel projects, where two TBMs bore parallel twin shafts, the Scarborough subway expansion project is a single-tube tunnel. Metrolinx states, “At 10.7 meters wide, this will be the first subway tunnel in Toronto to contain two subway tracks running in both directions.”

The crews have already started work on the project’s working shaft, where they will pull the TBM out of the ground after completing its tunneling journey.

In May 2021, Metrolinx and its provincial partner Infrastructure Ontario (IO) awarded Strabag a $757.1 million fixed price contract to design, build and finance the tunnel for the Scarborough Subway Extension project.

The Strabag team includes:

A drone photo of the large excavation for the TBM at the launch shaft site, image courtesy Metrolinx

The area of ​​responsibility includes:

  • Completion of other activities required for construction of the tunnel (e.g.: laying of utility lines, support of shafts and end walls, temporary power supply, lighting, ventilation and drainage).

IO says the team will deliver this contract “using a design-build-finance (DBF) model. Key benefits of a DBF model include significant risk transfer to the private sector over the life of the project contract, greater cost and schedule certainty, and greater potential for design and construction efficiencies and innovation.”

In November 2022, Metrolinx and IO selected Scarborough Transit Connect as a development partner (known as “Dev Co”) to enter the development phase of the Stations, Rail and Systems (SRS) contract for the Scarborough Subway Extension project.

Location of future production shaft near Eglinton Avenue East and Midland Avenue where the TBM will resurface after tunneling is complete, image courtesy Metrolinx

The Dev Co consortium consists of:

  • Applicant leads: Aecon Infrastructure Management Inc., FCC Canada Ltd.

  • Design Prime Team Member: Mott MacDonald Canada Limited.

  • Construction Prime Team Members: Aecon Infrastructure Management Inc., FCC Canada Ltd.

Dev Co workspace includes:

  • Design and construction of three new subway stations and bus terminals at each station;

  • design and construction of emergency exit buildings, service buildings and substations for traction current;

  • Installation, testing and commissioning of all systems and equipment and connection to TTC systems.

  • Design, supply, installation, testing and commissioning of all track and track components as well as a pocket track east of Kennedy Station.

  • Coordination with Strabag on remaining work.

A drone image taken in August 2022 looking east to work in Eglinton and Midland, image courtesy Metrolinx

According to IO, “The project will be delivered using a Progressive Design-Build (PDB) model. One of the key features of a PDB model is the opportunity for greater collaboration between the project owner, the successful bidder, project partners and communities.”

Metrolinx claims that when it opens, the subway expansion will attract 105,000 newcomers daily, including 52,000 from new public transit users. It will connect up to 38,000 passengers daily within a ten-minute walk of the transit. It will also improve access to jobs, with up to 34,000 jobs within walking distance of transit. Metrolinx also says that expanding the subway could reduce annual greenhouse gas emissions by 10,000 tons.

The future subway will allow passengers to travel with GO Transit trains along the Stouffville Line and TTC subway trains along Line 5 Eglinton (aka the Eglinton Crosstown Light Rail Transit Line) and a future eastern segment to take route 4 Sheppard. They can also transfer to and from TTC buses, GO and Durham Region Transit buses on a number of routes.

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