Highway 401 and 409 rail tunnels reach substantial completion

Aug. 5, 2021
Metrolinx has been constructing the tunnels under 21 live traffic lanes using ‘an engineering bit of urban magic.’

Two tunnels that will help increase capacity on GO Rail’s Kitchener Corridor have reached substantial completion, a milestone Metrolinx says marks the end of heavy construction, with only finishing touches and repair of minor deficiencies left to be completed.

Construction to excavate the tunnels began in July 2019, with completion of the first tunnel excavation achieved in August of 2020 followed in February 2021 with completion of the second tunnel excavation.

Metrolinx reports approximately 73,500-square meters (87,905-square yards) of debris was excavated for both tunnels. They were constructed using the sequential excavation method, which splits excavation into segments and performs the excavation in small amounts. Metrolinx determined the best way to excavate the tunnels was to dig from both ends and meet in the middle by hollowing out the top half of the tunnel first and working toward the median. Tunnel two’s final breakthrough took three days as crews cut open a three-quarter-inch thick steel wall with a torch.

The excavation description is enough to get any engineering professional’s heart beating, but Metrolinx says the real “engineering bit of urban magic” is that the work took place less than three meters (9.8 feet) beneath 21 active lanes of Highways 401 and 409 without disruption to traffic.

“The project is a significant achievement and provides key infrastructure for the Kitchener line,” said Franca Costantino, Metrolinx senior manager of the project delivery team. “The tunnels will eventually help get more commuters off the roads and onto public transit, improving quality of life for many people.”

As crews worked to excavate the tunnels, shotcrete was applied, followed by installation of the final liner, which smooths the tunnels for track installation to take place. Metrolinx says the final lining work took place in May 2021.

In 2017, Toronto Tunnel Partners (TTP) was awarded a C$116.9 million (US$91.88 million) contract by Metrolinx and Infrastructure Ontario to build the two tunnels. TTP is working with Metrolinx to perform finishing touches and correct any minor deficiencies, such as final smoothing of the concrete of the tunnels or retaining walls.

The next steps for construction of the tunnels include track installation, signaling and communications infrastructure, which will be performed under a separate contract.

About the Author

Mischa Wanek-Libman | Group Editorial Director

Mischa Wanek-Libman serves as editor in chief of Mass Transit magazine and group editorial director of the Infrastructure and Aviation Group at Endeavor Business Media. She is responsible for developing and maintaining the editorial direction of the group and is based in the western suburbs of Chicago.

Wanek-Libman has spent more than 20 years covering transportation issues including construction projects and engineering challenges for various commuter railroads and transit agencies. She has been recognized for editorial excellence through her individual work, as well as for collaborative content. 

She is an active member of the American Public Transportation Association's Marketing and Communications Committee and serves as a Board Observer on the National Railroad Construction and Maintenance Association (NRC) Board of Directors.  

She is a graduate of Drake University, where she earned a Bachelor of Arts degree in Journalism and Mass Communication with a major in magazine journalism and a minor in business management.