The City of Toronto is weighing its options for a large park that would add the sort of urban greenspace to its downtown that’s been made famous by New York’s Central Park and Vancouver’s Stanley Park -- an ambitious plan that calls for a more modest scale, but a decidedly bolder design.

City council unanimously approved $2.4 million to begin design work for the project on Wednesday.

As it stands, the proposal for Rail Deck Park would see 21 acres of public greenspace constructed above a stretch of the city’s existing downtown rail corridor at an estimated cost of $1.05 billion.

The size of the park would be a far cry from Central Park’s 843 acres or Stanley Park’s sprawling 988 acres. Of course, neither was built on top of rail lines that carry hundreds of thousands of commuters every day.

The park would serve one of the city’s busiest enclaves near the Rogers Centre, CN Tower, Air Canada Centre, the financial district and Union Station.

Some city councillors in the downtown core say the project will address the city’s greenspace deficit.

“If you want to build a city that’s liveable and great for both residents and visitors, then you need to pay for it,” Trinity-Spadina councillor Joe Cressy told reporters Wednesday.

Toronto Mayor John Tory has said the city’s eagerness to approve new office and condominium developments over the years has left parkland is short supply. Toronto’s downtown population is expected to double in the next 25 years.

Some skeptical suburban councillors are already wary of the price tag.

“This whole thing about a billion dollars … it’s pulling the wool over everyone’s eyes. It’s actually going to be about ($3 billion),” said York West councillor Giorgio Mammoliti.

The issue of air rights could also pose a challenge to the project. The air rights to the tracks are currently owned by the Canadian National Railway Company. The city will have to purchase those rights or be granted permission by CN in order to add a deck to the track and develop the space above it.

The Rail Deck Park proposal has drawn comparisons to Chicago’s Millennium Park. The now world-renowned project started as a modest proposal for open green space in that city’s centre, but far exceeded its original budget.