Elected members of all three levels of government gathered Wednesday to celebrate a landmark phase of the $2.6-billion Toronto-York Spadina subway extension.

This phase of tunnel construction is the first to cross the City of Toronto’s boundary as two tunnel boring machines – “Yorkie” and “Torkie” – create twin, one-kilometre tunnels from the future Highway 407 Station in York Region to the planned Steeles West Station at a rate of 15 metres a day.

“This is literally ground-breaking,” TTC CEO Andy Byford told CP24 after a snowy and cold outdoor news conference at the Highway 407 Station construction site. “I cannot wait to get this line open.”

Eventually, the 8.6-kilometre extension will stretch from Downsview Station (currently the last stop on the Yonge-University-Spadina line’s west branch) through York University to the future Vaughan Metropolitan Centre, near Highway 7 and Jane Street, by the time it is completed in late 2016.

Of the six new subway stations being built, the Highway 407 and Vaughan Metropolitan Centre terminals will be the first TTC stations to be constructed outside of Toronto.

At the news conference, Mayor Rob Ford, Ontario Premier Kathleen Wynne and federal Labour Minister Lisa Raitt and others championed the extension as a way to reduce gridlock in the GTA.

There are concerns, however, that the increase in ridership will add more pressure on a Yonge-University Spadina subway line that is nearing capacity amid worsening overcrowding on trains and congestion at some stations.

At a meeting last year, the TTC board endorsed a proposed downtown relief line and made the line’s construction a condition of any further expansion of the Yonge-University-Spadina line.

According to Ford, the ongoing Toronto-York Spadina extension will provide new options for hundreds of thousands of daily commuters, improve travel times and create better productivity for GTA businesses, in addition to creating more than 2,000 construction jobs.

The TTC is overseeing the project, which is funded by the provincial government ($870 million), federal government ($697 million), City of Toronto ($526 million), and York Region ($352 million).

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