Metrolinx Regional Express Rail (RER)

Greater Toronto and Hamilton Area (GTHA), Canada

Air quality, noise and vibration analyses for an ambitious regional rail system upgrade

The Ontario government is making substantial investments in transportation infrastructure to better serve the more than 6-million people who live in the GTHA today, and the 8.6 million expected to be occupying the region by 2031. As part of this work, Metrolinx, an agency of the government, is implementing Regional Express Rail (RER) service on the GO Transit Rail network. The intention of this change is to improve the region’s transit efficiency and transportation integration. Metrolinx expects the system will serve 127 million riders a year by about 2029, nearly double what it saw in 2015


  • The Challenge

    The introduction of RER will involve changes to both service and infrastructure. When fully implemented, the rail system will offer more and better service, including all-day service, greater frequency of departures and faster rides. RER will also entail the conversion of several key rail corridors from diesel to electric train propulsion.

    Metrolinx and its technical consultants, Gannett Fleming and Morrison Hershfield, engaged us to support the electrification project’s environmental assessment (EA) by estimating changes in air contaminants and environmental noise and vibration resulting from development of the RER system, and to propose mitigation measures as necessary.

    RWDI has an extensive track record of delivering advanced air quality, noise and vibration analyses to firms and governments for a range of applications, including several other Metrolinx projects. This project, focused on a rail system linking people, commerce and communities across an 8,200 km2 region, and is our largest to date.

  • Our Approach

    After working closely with the agency and its engineers to understand the scope of the questions to be answered, we evaluated:

    • changes in noise conditions resulting from the increased rail traffic;
    • noise and vibration effects resulting from the conversion of key rail lines from diesel to electric;
    • mitigation options where noise and vibration were expected to exceed set limits;
    • temporary noise and vibration issues likely to result from the construction phase of the project, and mitigation measures for these; and
    • changes in air contaminants due to the conversion from diesel to electric.

    Our work focused on the rail corridors slated for electrification, which were also those expected to experience the greatest increases in traffic: Lakeshore East, Lakeshore West, Stouffville, Barrie, a portion of the Kitchener corridor and Union Station.

  • The Outcome

    We delivered intelligence to Metrolinx on air quality, noise and vibration effects likely to result from their planned changes and upgrades to the GTHA’s regional rail system. Our analyses enabled the agency to make detailed design choices and adopt mitigation strategies with confidence. Under a concurrent project, we also developed an environmental guide for their staff, partners and consultants to support them in assessing and mitigating noise and vibration impacts from future rail developments.