The city's vision for Rail Deck Park — a proposed 8.5-hectare green space built in the air above the downtown rail yards — will cost Toronto at least $1.05 billion, according to early estimates released by municipal staff Thursday.

Those figures are based on other developments also built on decking, like Hudson Park in New York and Chicago's Millennium Park. Toronto's park would be built on a deck overtop the rail lines running from Bathurst Street to the Rogers Centre.

The Rail Deck Park report, which goes to Mayor John Tory's executive committee Sept. 22, acknowledges that the $1.05-billion pricetag is still an early estimate. A more detailed one likely won't be available until some time next year, should the committee approve the report's recommendation to pay for the creation of a detailed park plan, which would cost $2.4 million.  

Toronto residents react to #RailDeckPark0:56

Mayor John Tory has been a vocal supporter of the plan since announcing it last month, a sentiment he echoed Thursday night in a media statement.

"Today's staff report demonstrates important progress ... and reinforces my belief that this park is both entirely feasible and entirely necessary," the statement reads.

Toronto's downtown wards have less parkland per resident than almost any other part of the city. Ward 20, where Rail Deck Park would be built, has roughly 5.95 square metres of parkland per person — about one eighth the size of a tennis court. 

Lots of grey, little green

The city recognizes its downtown is "park deficient," Toronto's chief planner Jennifer Keesmaat said, a reality that she said is spurring both the push for the Rail Deck Park and the Under Gardiner project.

That's an issue that will only get worse if municipal staff's growth projections are accurate; in the next 25 years, the city expects to add 275,000 people to the downtown area. Right now, roughly 200,000 people live there, although even more people are in the core each day thanks to working commuters and tourists, the report says.

What must accompany that growth, however, is residential development. And it's that development that municipal staff are banking on to help pay for the park.

Spadina to Rogers Centre

The downtown core has fewer large park spaces than the outlying districts. (Stephanie Matteis/CBC)

Instead of creating parkland as required by city bylaws, the new developments can provide cash in lieu to help fund Rail Deck Park, the report recommends.

Staff say the city should also tap into its Section 37 funds — which developers agree to pay to finance neighbourhood improvements in exchange for the right to build taller buildings than the city normally allows — to help pay for the park.

Planners should also explore other public and private partnerships, the report says, both to fund the park's construction and to help with its yearly maintenance bill. 

There's no mention, however, about exactly how much revenue the development boom is expected to generate. Instead, the report says that the planning process will look at ways to pay for the project that won't increase Toronto's debt load.