Digging down and building up a tunnel at Toronto’s Agincourt GO Station

A new pedestrian tunnel is set for installation at Agincourt GO Station and Metrolinx News is going to show you how it’s done. Can you, um, dig it?

As major improvements are underway across the Stouffville GO Corridor, EllisDon, the project contractor, is preparing to install a new north pedestrian tunnel at the Agincourt GO Station beneath the busy railway.

This work is all part of improving Agincourt GO Station, giving transit customers better station amenities and access to future all-day, two-way frequent GO train service. 

Building an underground passage is no easy task, but after installing the south pedestrian tunnel in 2019, EllisDon has the process mastered.

To prepare for the tunnel installation, the elevator and stairwell accessways on either side of the track have been constructed over the last several months. Shoring systems were installed and the areas adjacent to the track were excavated to allow for the concrete structures to be cast in place.

The precast concrete sections of the tunnel that will go below the tracks have been fabricated offsite and will be delivered to the station before the major track closure this weekend.

A section of track will be removed to allow the tunnel crossing location to be excavated. Once excavation is complete, underground utilities will be put in place and a steel beam grid will be installed to act as the foundation and support the concrete tunnel sections.

Construction workers pour concrete for the roof of a pedestrian tunnel at Agincourt GO
Prepping for the tunnel installation: Pouring the concrete cast of the tunnel roof. (Metrolinx photo).

The precast concrete tunnel sections will then be lowered into place by a crane. The sections are connected and the structure tensioned, waterproofed and then backfilled. A sub ballast layer is constructed on top of the tunnel along the alignment of the track to support the weight of the train.

To top it all off, the rail track is reconnected and ballast (rocky material) is tamped down between the rail ties.

The installation will be a major achievement; however, travellers will have to wait a little longer to use the tunnel as it will open to the public next year.

In the infographic below, Metrolinx News gives you an inside look and breaks down the tunnel install step-by-step. From the top to the bottom, to the top again, it’s hard to believe all of this work happens over the course of one weekend.

A major track closure is planned to accommodate this crucial stage of construction.

Crews will be working over the weekend of December 11-13 to install the tunnel and must close rail service on the Stouffville line as the work requires disconnecting and digging below the tracks.

Stouffville GO customers that plan to make this part of their weekend route are advised to plan ahead, check schedules online and be prepared to take a GO bus over the weekend. Regular GO train service will resume on Monday, December 14.

Although pedestrian tunnels are a less visible form of crossing in comparison to an overhead pedestrian bridge, they are an important part of pedestrian safety and community connectivity, and this will be especially true for those that live or work in the Agincourt community.

This new north tunnel will replace the path along Marilyn Avenue and drastically improve pedestrian connections to and through the station.

While installing the tunnel marks a major milestone in the project construction, it will be some time until the tunnel will be fully open for passenger use. Additional amenities will need to be installed including lighting, railings, signage and the north elevator connection.

When the Agincourt GO construction is complete, customers will have access to a new second track and platform, a renovated existing platform and two new pedestrian tunnels with elevators. This work supports GO Expansion for more frequent, all-day, two-way service on core segments of the network.

To learn more about Agincourt GO visit here.

Story by: Teresa Ko, Metrolinx senior advisor