It's a stretch of park that could be bigger than Christie Pits or Eglinton Park, and has been conceived to meet the changing needs of a part of Toronto that was, not long ago, a collection of warehouses and rail lines.

If built, Rail Deck Park could transform downtown, creating at least 8.5 hectares of new green space — roughly the size of 15 soccer pitches — by building over the railway tracks between Bathurst Street and the Rogers Centre, and potentially over to York Street.

Toronto needs Rail Deck Park for three key reasons, according to the city's chief planner, Jennifer Keesmaat:

A shortage of green space in the area.

A dense and growing downtown population.

An increase in the number of families in the area.

The proposed park would be built on top of a stretch of Toronto's waterfront rail corridor, giving downtown residents a huge green space to enjoy. (Jennifer Keesmaat/Twitter)

Those factors are creating pressure that Rail Deck Park would ease, Keesmaat says. "We have a deficit in the park space where you could argue that public space matters more than anywhere else, and that becomes a critical part of livability."

Green deficit

As part of developing a broad plan for downtown development, city staff have been looking at population growth and at how land is currently being used. Among staff conclusions: there is a deficit of downtown parkland, and in particular, of larger parks.

According to their research, there are 121 parks in the area that total about six per cent of the land, but almost three-quarters of those parks are small (defined as less than 0.5 hectares) and "typically considered to be parkettes."

Existing downtown parks and green spaces. (TOcore report/City of Toronto)

Staff also measured the number of park users across the city and found that downtown parks are under greater pressure. More people use them — both in terms of total numbers and the average density of people — at all times of the day, on weekdays and on weekends.

Urban designer Ken Greenberg, who lives near Portland and Wellington Streets, in the heart of one of the areas that would be affected by Rail Deck Park, said parkettes are heavily used in the downtown core.

He said people living and working in his neighbourhood can't make a quick trip to the island or High Park on a lunch hour and they turn to parkettes, such as the one near him.

"It's a 2.5-acre space," he says. "It's overrun. The intensity of use risks destroying it, and you have the same argument for other spaces."

A denser core

It's only going to get more intense.

Population growth downtown has already exceeded the city's expectations in the last 15 years, and downtown is now growing four times faster than Toronto as a whole.

Currently more than 240,000 people live downtown. That number is expected to hit 500,000 by 2041.

Keesmaat says density should influence how space is used. On King Street, for example, cars use about 64 per cent of space while making up only 16 per cent of road users in the area. The majority of road users are pedestrians, cyclists or transit riders.

So the park's design — running east-west, parallel to overstressed roads —is intended to ease that congestion. "It's a linear connection that will mean if you live in Liberty Village and work downtown you're going to bike to downtown," Keesmaat said.

The park's east-west path parallels many congested roads, like King Street, and would give residents other ways to travel in and out of the core, like biking or walking. (CBC)

The park isn't just intended to be a place to hang out, but a way to help people make different choices about how to get around.

This represents a philosophical and practical shift in planning. When Frederick Law Omsted designed Central Park in New York, it was intended to provide an escape from the city.

Greenberg said green space is not just about providing relief.

"Now there's the notion that green space is networks connecting streets, lanes, pieces of railway, corridors along the water bodies. The ways people are using spaces are much more fluid," he said.

Downtown 'baby boom'

There's also the question of how people would like to start using them.

Keesmaat emphasized that an increasing number of residents want to stay downtown rather than moving away to have children.

More families want to raise their children downtown, says Toronto's chief planner. (Stephanie Matteis/CBC)

The downtown core is "in the midst of a baby boom," she said, pointing to the glut of strollers at CityPlace as evidence that downtown is changing.

"Families want to stay downtown but they feel pressure to leave. How can we ensure we're meeting the needs of families so they can raise their families in an urban environment?"

Through surveys, the city has learned that right after better access to childcare, parents list increased green space as a top priority.

Making it happen

Rail Deck Park also could be about "identity building," according Mitchell Kosny, interim director of Ryerson University's school of urban and regional planning. A marquee green space "helps attract business, development, people, culture."

Kosny was disappointed the city didn't have a funding plan or backers in place before announcing the new park.

"When you hear: 'Here's another great idea but do you have one cent committed to it? Nope,' I get worried. I don't like the openness that lets the private sector figure out what we get for it."

Staff will provide city council's executive committee with more details about the proposed park, including implementation and community engagement strategies, at a meeting on Sept. 22. But according to Keesmaat, it was vital to first assess public response. So far, she says, it has been positive.

"It would be outrageously presumptuous to say, 'Here's the plan. Here's how we're going to pay for it,'" before getting that reaction, she says. "When they're talking about how to pay for it, that's how I know we got it right."