The next stage of the Spadina subway extension into York Region has officially begun.

Earlier today Premier Kathleen Wynne marked the occasion at the Highway 407 subway Station west of Jane Street.

Thew stations are also being constructed at York University and the yet-to-be-built Vaughan Metropolitan Centre, which will define the city’s ‘new’ downtown.

The mega-project has already experienced serious setbacks.  In 2011, work at the York University station was shut down for several months after a crane operator was killed on the construction site.

TTC officials later said the death delayed the opening of the line’s new stations by about a year.

Service isn’t expected to begin on the 8.6-kilometre subway tunnel until at least fall 2016.