The new Ontario Line subway has just crossed its most important construction milestone to date, with the province announcing on Friday that it had broken ground on the tunnelled phase of the new 15.6-km line connecting Exhibition Place with the recently-shuttered Ontario Science Centre.

Friday marked the start of excavation for the tunnel's launch shaft at the future Exhibition Station, kicking off construction of the first major subway tunnel constructed through downtown Toronto in more than six decades.

It has been a hot start to construction since the project's December 2021 ground breaking. Now approaching the three-year anniversary of shovels hitting the ground, work is set to embark on the six-kilometre-long tunnels that will carry Ontario Line trains between Exhibition Station and a portal just west of the Don River.

Preparation work for the 16-metre-deep launch shaft has been underway since mid-2024. Once the shaft is excavated, massive tunnel-boring machines will be lowered into the pit to begin carving their way eastward toward the Don. After the shaft serves its initial purpose, it will be transformed into the future west portal, where Exhibition-bound trains emerge from the tunnels.

The @OntarioLine will soon have their very own tunnel boring machines, and work is now underway to dig the launch shaft they will begin tunnelling from. This is an extra special milestone because it marks the start of the first subway tunnelling project to start in Toronto's… pic.twitter.com/OfOEScoBqu

— Metrolinx (@Metrolinx) November 22, 2024

Provincial officials were on hand alongside Metrolinx executives to celebrate Friday's big news.

"The start of excavation to support tunnelling throughout the downtown core represents another major development for the Ontario Line and for the people of Toronto," said Metrolinx President and CEO Phil Verster.

"With station, bridge and above-ground track construction now underway across the route, we are gaining critical momentum on a project that will curb crowding on transit lines and roadways by putting 227,500 more people within easy reach of fast, safe and reliable transit."

Prabmeet Sarkaria, Minister of Transportation, hailed the achievement as a big step after "more than 60 years since the first subway tunnels were built in downtown Toronto."

I was joined by @KingaSurmaMPP and @CHogarthPC to announce the start of excavation for the tunnel boring machine shaft for the Ontario Line subway tunnels at Exhibition Station – marking the first subway tunnel built in Toronto in 60 years.

Under Premier @fordnation's… pic.twitter.com/YhjBBzVB73

— Prabmeet Sarkaria (@PrabSarkaria) November 22, 2024

Ahmed Hussen, Minister of International Development, spoke on behalf of Sean Fraser, Minister of Housing, Infrastructure and Communities, calling the project "one of the biggest partnerships to construct public transportation in Canadian history."

"Work is progressing and today's groundbreaking is another step toward affordable, reliable and quick public transit for Torontonians," said Hussen.

The new launch shaft-turned-portal near Exhibition Station is just one cog in the broader Ontario Line project, one of the largest and most expensive engineering projects underway in Canada right now, with a projected price tag north of $27 billion.

The route, expected to enter service by 2031, is projected to put an additional 230,000 Toronto residents within walking distance of public transit.

It will also create vital connections that will relieve the burden on existing stations like the dangerously overcrowded Bloor-Yonge and St. George Stations by creating new transfer points at the junction of the busy Line 1 and Line 2 subways.

The Province states that commuters will be able to shave as much as 40 minutes in travel times, claiming that "a trip across the city from Exhibition Place to the Eglinton Crosstown LRT at Don Mills Road will take 30 minutes or less compared to the hour and 10 minutes it takes today."