Construction of Toronto's Yonge Line 1 North Subway Extension (YNSE) reached a milestone in late October, according to UrbanToronto. On October 26, Metrolinx announced the arrival of the first of two tunnel boring machines (TBMs) that will dig twin 6.3-kilometre subway tunnels.

The machines will be assembled in a launch shaft near Highway 407 and will then tunnel south toward Finch Station. The shaft, located just south of Langstaff GO Station and east of Yonge Street, was completed in July. Nearly 70,000 cubic metres of soil were removed to build it. Once the project is complete, the shaft is planned to become a tunnel portal for the above-ground section.

About the extension

The YNSE extends Line 1 north along Yonge Street from Toronto into York Region. The route curves east beneath Royal Orchard in Markham, then turns north and runs at grade along the existing Canadian National/GO rail corridor, ending just east of Richmond Hill Centre. According to UrbanToronto, the project will add five stations at Steeles, Clark, Royal Orchard, Bridge and High Tech, and about eight kilometres of subway route.

The original plan was a six-station, fully underground extension along Yonge Street. The provincial government scaled it back in 2021 to reduce rising costs. The revised alignment moves the northern section to the surface and cuts the station count to five. A deeper tunnel realignment in Royal Orchard was also approved to reduce the number of homes directly above the route.

Current progress

The first TBM was prepared in Germany and is being lowered into the launch shaft, where assembly is underway. Tunnelling equipment and support systems are being loaded, and the second TBM is expected to arrive.

Along the route, demolitions and site clearing are underway near the future Steeles, Clark and Royal Orchard stations. Road widening and piling are taking place at Yonge Street and John Street to prepare a site for an emergency exit building. Monitoring equipment has been installed along the extension to track possible construction impacts.

What remains

The tunnelling contract has been awarded. A separate contract for stations, rail and systems has not yet been awarded, and a selection is expected in 2027. Metrolinx has not yet confirmed an opening date for the start of TBM excavation. According to UrbanToronto, these open questions create uncertainty about the project's delivery schedule.