The federal government will contribute $1.53 billion towards the cost of Calgary's planned Green Line public transit project.

Calgary Southeast MP Jason Kenney, who made the announcement Friday morning in Mount Pleasant, called it the biggest single federal investment ever made in Calgary.

Calgary Mayor Naheed Nenshi says the money means the project can be built as an LRT line immediately, skipping the planned intermediate step of making the Green Line a bus rapid-transit system.

Nenshi called it a historic day.

"Soon, if you can imagine it, we will see state-of-the-art light-rail transit emerging from downtown, crossing the river into this escarpment, serving upwards of 40 million passengers a year," he said.

Construction to finish by 2024

Construction will get underway in 2017 and be finished by 2024, Nenshi said. It will nearly double the size of Calgary's current C-Train network.

The Green Line will run from Calgary's northern outskirts, down Centre Street, through downtown and into the deep southeast to the South Health Campus.

The overall cost of the mega-project has been pegged at about $4.5 billion.

In 2013, council voted to use $52 million in yearly tax surpluses from 2015 to 2024 to fund the Green Line project.

Coun. Shane Keating says if that policy were stretched out to 20 years, the city would be able to pay for about one third of its cost.

Provincial funds?

It remains to be seen whether the province will commit to funding the remaining third of the Green Line's price tag.

Nenshi says the time is right for governments to invest in stimulus spending.

"With the current interest rates, money is as cheap as it's ever been. We certainly want to create jobs," he said, predicting the project could create as many as 23,000 jobs.

Ottawa's contribution comes from the new Public Transit Fund that will "provide significant permanent support for large-scale public transit projects that address congestion and reduce travel time," the federal department of finance said in a release.

The Green Line will use low-floor train cars that are boarded at street level. Until Friday's funding announcement, the provisional plan was to start running buses on the southeast alignment by 2021 and convert the transitway to an LRT route at a later date.