Update | On Thursday afternoon, the provincial government made the announcement to fund a $50-million extension to the Trillium Line.

The Ontario Liberal government is expected to announce that it will fund a $50-million additional extension of Ottawa's Trillium Line that will see the light rail system stretch to the future site of Riverside South's town centre at Earl Armstrong and Limebank roads.

Liberal MPPs will join members of council and Mayor Jim Watson at his office Thursday afternoon to make the funding announcement.

Although the event is not technically a campaign pledge, presumably the Liberals would have to win the upcoming provincial election to make good on the promise.

While an earlier estimate put the price tag of the Riverside South extension at $30 million, sources familiar with the deal told CBC the amount is now $50 million.

Concept art for how the LRT might look in Riverside South. (City of Ottawa)

Closer to residents

The $3-billion second phase of LRT, already in the planning phases, will see light rail extended to the west, east and south ends of the city. The original plan for the southern extension included a spur line to the airport, but saw the track stop in the middle of an open field on Bowesville Road, just south of Leitrim Road.

However, last July the city announced it would extend the southern alignment by 800 metres to the edge of the urban boundary — south of Earl Armstrong Road — on the existing rail corridor before connecting with Bowesville. The city expected to be able to make this adjustment to the line within its existing Stage 2 budget.

The city was also hoping to then extend the line westbound track by three kilometres to Limebank, which is the location of a new planned town centre in the burgeoning community of Riverside South. Even without the new development, the Limebank location is closer to more residents than the older plan.

The southern extension is scheduled to be completed by 2021. It's unclear if this new extension could be built within the same time frame.

The Liberals have already pledged about $1 billion to Stage 2 of the LRT project, including an extension to Trim Road and the airport link.