Prime Minister Justin Trudeau joined the Ontario premier and Toronto mayor at the opening of the new subway extension, where service begins for transit riders on Sunday.

The prime minister and other dignitaries cut the ribbon to open the line 1 extension Friday morning at the Vaughan Metropolitan Centre stop.

They then rode the subway to the York University stop, where they held a press conference. Trudeau called the extension, "great news for students, commuters and families."

Transit services "have had trouble keeping up with the growing demand," Trudeau said. The extension "will mean a faster commute, less time in traffic and more money in people's pockets as they trade their cars for a subway ticket."

Trudeau cuts the ribbon on Spadina Subway1:32

The extension extends line 1 by 8.6 kilometres to the new Vaughan Metropolitan Centre, and adds about 13 minutes of travel time along the route. Total travel time from the Vaughan station to Union Station downtown is 42 minutes.

There are six new stations along the route: Downsview Park, Finch West, York University, Pioneer Village, Highway 407 and Vaughan Metropolitan Centre.

The stations are all fully accessible, WI-FI-, cell- and Presto-enabled and have amenities such as bike facilities, said TTC chair Josh Colle. 

"This is what the modern TTC looks like: modern, accessible and connected," Colle said.

'Big transit takes time'

While the official ribbon cutting happened today, service begins Sunday at 8 a.m.

The city estimates that the extension will add an estimated 36 million transit trips and eliminate 30 million car trips per year. That includes the first-ever subway trips to York University.

"The subway expansion to Vaughan is the largest subway expansion in a generation," Premier Kathleen Wynne told reporters.

"Big transit takes time, and we know that. It's no small feat that we are standing here today."

The extension cost about $3.2 billion.

The opening marks the first expansion of Toronto's subway route since the Sheppard line opened in 2002.

Toronto Mayor John Tory said Friday that residents won't have to wait as long for another major transit project to come into service.

"We are not ever again going to wait 15 years for a significant transit expansion in this region," he said, noting that the 19-km Eglinton Crosstown LRT is well underway.