A planned extension of the Yonge subway line into York Region is moving ahead with a request for proposals (RFP) to design and build the tunnels, the Ontario government said Friday.

The Yonge North Subway Extension is a long-promised project, which will see the TTC's Line 1 subway extended eight kilometres past Finch, and up into Thornhill and Richmond Hill.

The project was talked about for years, but was unfunded. Critics had also pointed out that the previously-overcrowded subway would not be able to cope if it was extended, but that issue is expected to be dealt with through the estimated completion of the Ontario Line in 2031 to take pressure off Line 1.

The Ford government identified the Yonge extension as one of four priority subway projects for the Greater Toronto Area back in 2021, along with the Ontario Line, the Scarborough Subway Extension, and the Eglinton Crosstown West Extension.

“The RFP release is the next critical step in our government’s plan to extend subway service north from Finch Station to communities in Markham, Vaughan and Richmond Hill, for the first time ever,” Minister of Transportation Prabmeet Sarkaria said. “As York Region grows, we’re building the Yonge North Subway Extension to ensure our transit infrastructure keeps up, while providing people with access to better, more reliable public transit.”

The RFP process will select one of the three groups previously identified through a request for qualifications process earlier this year. They include CrossTransit Group, North End Connectors and Toronto-York Tunnel Connectors.

The contract for the tunnel work is expected to be awarded late next year.

When complete, the extension will add five stations to the Yonge line, with stops at Steeles Avenue, Clark Street, Royal Orchard Boulevard, a transit hub between Highway 407 and Highway 7, and Richmond Hill Centre, where it will offer connection with the Langstaffe GO Station.

The province also said Friday that upgrade work which began at Finch station to prepare for eventual subway construction is nearly complete.

The announcement comes as Metrolinx continues to face questions over the endlessly delayed completion of the Eglington Crosstown light rail line. CEO Phil Verster said two months ago that the provincial transit agency has a pretty good idea about when the line will open but not an estimate that they are confident enough to share publicly.

Verster reiterated that Friday when asked about the line at the announcement.

"So we are going to announce an opening date for the Eglinton Crosstown and we will do so three months in advance of opening," Verster said. "We are in the very last phase of that project and we know exactly what needs to be done to get it to completion and we've got a robust schedule.

"What the issue is that we're dealing with is the unpredictable findings we have during the testing phase and unpredictable timing impact that has on a potential opening day. That's why we're not declaring an opening day now but we are continuing to work vigorously to get us to do that opening date."

A target completion date for the Yonge North extension has not yet been unveiled, however the province has previously estimated all four of its priority subway projects will be complete by 2041.

An 8.6-kilometre extension of Line 1 into Vaughan opened in 2017, marking the first time the subway expanded beyond Toronto’s boundaries.