Image of a tunnel built for the Eglinton Crosstown LRT

What’s next for the Yonge North Subway Extension

Environmental studies will shift progress into high gear for this much-needed transit project.

Apr 15, 2021

There’s momentum behind the Yonge North Subway Extension, so we wanted to see what’s just over the horizon for the priority transit project. Especially when it comes to the environmental assessment phase, where experts probe everything from traffic flows to the features of the ground below the surface.

Much of the progress will be built on plans that were recently shared.

Image of a tunnel built for the Eglinton Crosstown LRT

The data surveyors collect about the soil and rock is essential to the design of subway tunnels. (Metrolinx photo)

The extension will add approximately eight kilometres of new TTC Line 1 subway service, from the existing Finch Station in North York all the way into Richmond Hill Centre. The work that is already happening to move the project forward will pave the way for the procurement process to begin. This feature will highlight the milestones that are around the corner and how your voice can be heard throughout the course of the project.

Exploring what’s below the surface

There’s a good chance residents who live near the subway route have spotted surveying crews in their community wearing reflective vests while gazing into instruments mounted on tripods. These investigations capture differences in ground elevation, as well as features of buildings, streets, walkways, utility poles and trees. Teams also use scanners to zero in on the precise location of underground utility lines so they can be marked on streets and sidewalks with a streak of florescent spray paint.

As surveying work continues, teams will occasionally need to drill deep into the ground to take samples of the earth below the surface to learn more about the geology of the area. The data surveyors collect about the soil and rock is essential to the design of subway tunnels and key to developing solutions for how to mitigate any possible noise and vibration during construction and operation of the extension. Ultimately, the analysis of street-level conditions and natural features of the area are critical to informing the design work Metrolinx does to refine its plans for the project.

Environmental studies and public input

The process of gaining a thorough understanding of the potential effects of the project on the environment, and how to limit them, is called an environmental assessment – an EA, for short. These studies are a critical step in any infrastructure project. Metrolinx is preparing an addendum to the existing Yonge North Subway Extension EA that will consider the changes since the previous EA process that was completed in 2014, evaluating the updated route and building on previous environmental studies.

A big part of the EA process involves looking at things like soil and groundwater quality, traffic patterns, the natural environment, and the various ways land in the area is being used. The potential for noise and vibration during the construction and operation phases of the project will also be extensively studied, as well as what will work best to reduce or avoid any impacts as much as possible.

a subway train.

Here’s a look ahead – A rendering of a TTC subway at Richmond Hill. (Metrolinx image)

Archaeological assessments are planned for the project and could include opportunities for Indigenous monitors to take part in field work to commemorate the history of the area, which is the traditional territory of many Indigenous Nations, including the Anishnabeg, the Haudenosaunee and the Wendat Peoples, and is on the treaty territories of the Mississaugas of the Credit First Nation and Williams Treaties First Nations.

The other key component of the EA process involves collecting input from the public, and engaging with Indigenous Nations. Metrolinx will reach out to local residents, community organizations, and Indigenous communities to hear their comments and feedback on the updated plans for the project. A draft report is expected to be published this fall that combines the data and input provided by Indigenous communities, the public and other stakeholders through both components of the EA process. These insights are vital to determine how to move the project forward in the best way possible. Virtual open house sessions are already underway and Metrolinx will share details about further opportunities for residents and Indigenous communities to provide input in the weeks and months ahead.

Refined analysis

Refinements to the Yonge North Subway Extension will come into focus through the development of an updated business case – the Preliminary Design Business Case, or PDBC.

A business case is a comprehensive collection of evidence and analysis that sets out the rationale for why an investment should be made. Business cases provide a rationale  to decision-makers, Indigenous communities, stakeholders, and the public as a crucial part of transparent and evidence-based decision making processes.

The PDBC builds off the previous analysis to further refine the design of the project and prepare it for procurement. The planning and design work done through the PDBC will be informed by the findings and feedback from stakeholders and the public collected through the environmental assessment process and will point the way forward for the project.  

The updated business case will fine-tune the route the extension will follow and confirm aspects of the project such as the size and depth of the subway tunnels. Together with its partners, Metrolinx is also updating the evaluation of Neighbourhood Station performance to inform which potential station could best complement the benefits of Steeles, Bridge, and High Tech stations, which are confirmed as moving forward. The locations that are part of the analysis for the fourth station are in line with the previously proposed Cummer, Clark, and Royal Orchard stations.

Moving closer to construction

This fall, the Yonge North Subway Extension is expected to reach an important milestone with an official call-out for teams interested in delivering the project to step forward.

A ‘request for qualifications’ – typically referred to as an RFQ – is the first step in the procurement process. It presents an opportunity for project teams made up of contractors, equipment suppliers and investors to demonstrate they have the experience and capability to take on the work required.

Once the project teams have been prequalified, a ‘request for proposals’ – also known as an RFP – is anticipated to kick off the next phase of the bidding process next year.

In the meantime, you can get the latest updates on the project delivered to your inbox by signing up for the e-newsletter through the Yonge North Subway Extension website and by following these social media channels:

Twitter – @YongeSubwayExt

Facebook – Yonge North Subway Extension

Instagram – @YongeSubwayExt

by James Moore Metrolinx communications senior advisor