Metro Vancouver mayors are expected to vote later this week on the first stage of a plan to extend the SkyTrain's Expo Line from Surrey, along the Fraser Highway toward Langley, but it remains unclear how far it will reach with current funding.

According to TransLink spokesperson Jill Drews, the next step is for the Mayors' Council to vote on Thursday on TransLink's proposal to develop a business plan for the extension.

"This is what we need to do to answer quite a long list of questions," said Drews.

That plan, which is expected to take about 15 months to draft, would likely split the project into stages, with the first stage focused on extending the elevated track along the Fraser Highway as far as the existing funding allows.

Previous estimates have suggested the first stage of construction could extend the line as far as Fleetwood, but Drews said that remains to be determined.

If that plan is eventually approved, it is expected that construction could begin in about two years, with construction completed by 2025, she said.

New funding from the provincial and federal governments will likely be required to complete the line to Langley, she noted. It is expected the entire line will include eight stations along 16 kilometres of track.

LRT scrapped by Surrey mayor

In November, the mayors voted to scrap plans for the Surrey-Newton-Guildford LRT project in favour of a SkyTrain along the Fraser Highway to Langley. Surrey Mayor Doug McCallum campaigned, and won, on the issue.

The LRT project was projected to be completed by 2024.

TransLink previously said replacing it with a SkyTrain to Langley would likely cause lengthy delays, but last week's report said the transportation authority is aiming to complete part of the project just one year later than anticipated.

In its report, TransLink said staff were asked to expedite plans in part so they could be presented to various levels of government in search of more funding.

The SkyTrain has previously been said to cost about $1 billion more than the LRT. The report did not provide an update on that estimate.

TransLink has already sunk $57 million on the first phase of the LRT project — which was previously estimated at about $77 million.

The staff report said TransLink would have to consider potential obligations to reimburse partners who signed on to any existing agreements.

The report also said the SkyTrain project would require TransLink scrap existing plans to run a high-capacity B-Line bus service along the Fraser Highway.

Instead, TransLink is proposing to improve the existing 96 B-Line along Surrey-Newton-Guildford — another busy corridor in the region which would have been helped by the LRT project.

TransLink has already studied potential for rapid transit along the Fraser Highway to connect Surrey and Langley, the report says. The transportation authority last updated those projections in 2017.

The route has been a priority for two decades, the report notes, because of population and employment forecasts for the area.