It's been expensive, but track work on the Toronto-York Spadina Subway Extension (TYSSE) is now complete.

Ontario Premier Kathleen Wynne appeared at the new line's future Vaughan Metropolitan Centre stop to announce the completion of the track work. The TYSSE will lengthen the western portion of Line 1 by 8.6 kilometres and add six stations north of Downsview.

Wynne said the subway, which connects Toronto and York Region, has "symbolic" significance and is a good example of the province's regional approach when it comes to transit development.

"Being a York Region girl myself, it's very exciting," Wynne told reporters.

TTC Chair Josh Colle said he's confident the new stretch of subway will be open by the end of 2017. The new stations, he said, are currently 90 per cent complete.

The extension has been plagued by problems, including an 18-month delay at the project's outset. In January, the TTC revealed that it needed up to $400 million to cover contractors' claims. The project's budget is now close to $3.2 billion.

Both Wynne, and federal Liberal MP Adam Vaughan, reiterated their governments' plans to help Toronto pay for its transit expansion plans.

Colle said "this is a very exciting time for transit in Toronto."

He also warned the city and province can't simply stop building transit once projects like the TYSSE and Eglinton Crosstown are finished.

"The new normal is building transit in this region," he said.

The TTC has posted a time-lapse video that shows the entire length of the subway extension.

You can watch it here.