Construction is in full swing for the new Ontario Line subway following its December 2021 ground breaking, but there's much work to accomplish if the line is to meet its expected completion by 2031.

The route will run 15.6 kilometres from Exhibition Station through downtown and all the way up to the Eglinton Crosstown LRT. The Ontario Line's stretch through the city centre includes a six-kilometre tunnel from Exhibition to the planned Don Yard portal, just west of the Don River.

But before the tunnel-boring machines (TBMs) can begin to carve away this tunnelled section of the line, crews must first excavate a launch shaft and portal from which the TBMs will be lowered into the ground and embark on their journey eastward.

The prelude to that big dig is now underway just east of the future site of the Ontario Line's Exhibition Station, where drilling rigs have begun to prepare the forthcoming portal and launch shaft for excavation.

Work has started on the tunnel boring machine launch shaft for the @OntarioLine in Liberty Village. Toronto is finally getting another downtown subway! pic.twitter.com/CWzw1az78c

— Alex Glista 🇨🇦 (@AlexanderGlista) July 9, 2024

According to a construction notice shared by Metrolinx in June, the portal "will allow Ontario Line trains to move from the street level station at Exhibition to the below-grade tunnel."

"When completed, the Exhibition Portal will also function as the tunnel launch for the machines that will create the tunnels for stations from Exhibition to Corktown."

The portal is being constructed immediately south of Liberty Village, next to the Toronto Police Traffic Services building, between King West Laneway and Hanna Avenue.

The current phase is expected to continue until at least the end of November 2024, and will be followed by the start of excavation activities.

Metrolinx expects a timeline of 2025-2026 for completion of the portal structure, the insertion of TBMs and the start of the eastbound tunnelling process.