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We used AI to measure Canada’s urban sprawl

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To combat climate change, cities need to control their urban sprawl and intensify population density. However, in the past two decades, the urbanized areas of major Canadian centres have grown by 34 per cent and their population density has fallen by six per cent.

Select a metropolitan region and see the areas developed between 2001 and 2021.

In 2001, {population2001} people were living in the metropolitan area of {city}. The urban area then extended over {urbanArea2001} square kilometres.

To rotate the visualization, click on it and hold as you move your mouse.

To rotate the visualization, click on it and hold as you move your mouse.

Twenty years later, {population2020} people live in the area— an additional {populationDifference}. And the urban area grew by {urbanAreaDifference} square kilometres.

“We’re a suburban nation,” said Sasha Tsenkova, a professor of architecture, planning and landscape at the University of Calgary, who looked at our findings.

In all, 1,700 square kilometres have been added to the country’s nine biggest metropolitan areas since 2001. It’s as if the country’s urban areas have increased by three-and-a-half times the size of the island of Montreal.

And since urban sprawl (up 34 per cent) has progressed on average faster than population growth (up 26 per cent), each Canadian occupies, on average, more space, farther away from city centres. In 2001, residents of the nine largest centres occupied an average of 317 m2 of urbanized territory. In 2021, it went up by 19 m2, an area equivalent to one to two additional parking spaces for each inhabitant.

“Urban sprawl contributes enormously to greenhouse gas emissions,” saidTsenkova. “It has an economic, environmental and social cost.” Instead of building new neighbourhoods, we should intensify those that already exist and add services and shops within walking distance, according to experts.

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How did we get these numbers?

The latest Natural Resources Canada maps for the country's urban territory date back to 2015. To cover the period 2001-2021, we used an artificial intelligence algorithm to recognize the urban areas. The computer program drew from several thousand satellite images, covering nearly 47,000 square kilometres, to create the maps shown at the beginning of this project, pulledfrom the 2016 geographical boundaries of the metropolises. For details, see the methodology at the end.

The development of less dense neighbourhoods designed for the automobile was a profitable business model in the 1960s and '70s. And we continue with that model today. According to our analysis, in neighbourhoods built less than 20 years ago, 60 per cent of the population lives in single-family homes. But this type of neighborhood exacerbates road congestion and pollution: 81 per cent of those residents use their cars to go to work. By comparison, in historic neighbourhoods, only 38 per cent of residents live in houses and 65 per cent drive their cars to work.

“Bad urban planning decisions are responsible for our transportation problems,” said Catherine Morency, a transportation engineering professor at Polytechnique Montréal and the Canada Research Chair in the Mobility of People. The best movement is the one that is not motorized, she explained. “If residents are unable to meet their needs without a vehicle, it doesn't work.” For people to get around on foot, they need a mix of services within walking distance of home. And for public transportation, a certain population density is necessary; otherwise, the low number of users makes operating costs very high.

In April, Statistics Canada published its proximity index. It measures a neighbourhood’s access to a range of services (groceries, pharmacy, daycare, schools, public transportation, parks, etc.) within walking distance. We cross-referenced this index along with Canadian census data and our geographical data.

This image shows 100 people commuting to work. Note: each bus holds up to 25 passengers. Choose a metropolitan area.

In medium amenity-dense zones{mediumDensityExample}, only some vital services are located nearby. In these neighbourhoods, the number of car commuters climbs to {carUsersMediumDensity} per cent. Other modes of transport become a minority. Of the newly urbanized areas in {city}, {newUrbanLandPercMediumDensity} per cent fit this profile.

In the low amenity-dense{lowDensityExample} zones, residents must leave their neighbourhoods in order to meet their basic needs. In these parts of {city}, the proportion of car commuters hits {carUsersLowDensity} per cent. The vast majority of vehicles move just one person, causing congestion.

In the {city} region, {newUrbanLandPercLowDensity} per cent of neighbourhoods built between 2001 and 2021 fall into this category, with few nearby services and a strong reliance on cars. In total, these newer urban areas, which did not exist 20 years ago, cover {newUrbanLandLowDensity} square kilometres.

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Just as the COVID-19 pandemic accelerated the adoption of remote work, it also could bring on a new wave of urban sprawl. “Before the pandemic, we already noticed people who worked from home had a higher tolerance for longer commute times,” explained Morency. In other words, they can accept living farther away because they travel less often for work. By living farther away, they have less access to public transit and, as a result, rely on cars to get things done.

And even if these remote workers travel less often than others in the workforce, we cannot forget the costs related to urban sprawl — be it for new roads, drinking water, power lines or networks of sewers. "When you build new low-density suburban neighbourhoods, below a certain population threshold, the financial cost of that new infrastructure outweighs the revenues that the municipality will get in return," said David Wachsmuth, an associate professor at McGill University and Canada Research Chair in Urban Governance. “In other words, we subsidize these low-density neighbourhoods.”

A study released in September 2021 by the City of Ottawa estimates that low-density subdivisions built on greenspace cost the municipality $465 per person annually. As for real estate developments with a higher population density, built close to already-urbanized areas, the municipality instead accumulates a net annual surplus of $606 per resident. This analysis, conducted by Hemson Consulting, takes into account capital and operations expenditures. In some municipalities, particularly in Western Canada, land developers must pay for the new infrastructure.

Despite expanding farther and farther, some cities still manage to densify. In Edmonton and Calgary, after an exceptional population growth over 20 years (up 47 and 52 per cent respectively), the number of people per urbanized square kilometre has also climbed (by five and 3.3 per cent). “The requisites for the new suburbs improved in the 2000s,” according to Sasha Tsenkova, with the University of Calgary. “They doubled the density requirements.”

However, these two centres remain among the most spread out in the country. Calgary's density is 21 per cent lower than the average of the regions studied in our analysis. The trend is the same in Edmonton, which is 39 per cent lower.

Toronto greenbelt
Toronto greenbelt Source : Greenbelt Foundation

Over the past 20 years, Toronto has also managed to increase its density. Despite the addition of 1.3 million residents, it remains the densest centre in the country. "In 2005, Ontario implemented a greenbelt around the outside of the city to prevent development in the Oak Ridges Moraine, the forests and the hills north of Toronto," explained Gordon. “They established a growth plan that had real teeth attached to it.”

In Vancouver, in addition to the mountains to the north, the ocean to the west and the U.S. border to the south, provincial law protects farmland. "There is little land available," said David Gordon, an urban planning professor at Queen's University in Kingston, Ont. Therefore, the city had to grow up rather than out. British Columbia has also encouraged urban development around Vancouver’s metro stations. Of all the centres studied, Vancouver experienced the smallest loss of density. It remains the second most dense region in the country.

A SkyTrain is seen in Vancouver.
SkyTrain, Vancouver transit Photo : Radio-Canada/Maggie MacPherson

The outlook is less rosy for other cities, such as Montreal — its density has decreased by 10 per cent over the past 20 years. “They looked at the island for too long, but the problem is not the island,” said Gordon. “The problem is the area off the island and the metropolitan regional planning.” After years of work, the Quebec government hopes to release an architecture and land-use planning policy by the spring of 2022.

According toWachsmuth, historical context can also explain the difference between Montreal and other major cities. “In Toronto, for example, you see newly built gigantic towers surrounded by an ocean of ​​single-family homes, because the city grew after everybody started buying cars.”

But in Montreal, by the time cars becamecommonplace, the city had already grown, with denser neighbourhoods made up of multi-family buildings, added Wachsmuth. On the island, there are therefore fewer single-family homes and those who wish to live in this type of dwelling buy new builds on the north and south shores. As property prices remain lower in Quebec compared to other provinces, new properties also tend to be more spacious than elsewhere in the country, further driving the phenomenon of sprawl.

To slow this exodus to low-density suburbs, especially for families, Wachsmuth thinks the provinces need to review their laws and regulations.

"We build two extremes in Canada: single-family homes or highrise apartments or condos. But it’s really hard to build anything in between there."

— David Wachsmuth, Canada Research Chair in Urban Governance

The lack of choice pushes parents who can afford it toward the suburbs, even if they would be willing to stay closer to the urban core.

There are also big incentives for homeownership in Canada. For example, there’s financial aid for people buying their first home. On the other hand, there are virtually no advantages to staying in the rental market, said Wachsmuth. “We mostly find rental housing in downtown settings and homes for sale in the suburbs. Without a pretty strong regulatory control, the housing system is going to produce lots of urban sprawl.”

“We cannot buy ourselves more time by purchasing hybrid and electric vehicles,” added Tsenkova. “The problem needs to be addressed at the source. We need to revitalize our downtowns and mature suburbs to keep families there. We need to bring urbanists, construction entrepreneurs, transit planners and environmentalists together to begin to do the right things.”

For Catherine Morency, the professor at Polytechnique Montréal, eco-taxation is also an option. “Currently, in Canada, travelling by car is relatively inexpensive. The cost of road congestion and parking pricing remains limited. When vehicles become more fuel efficient, people buy them bigger. It means that they are not looking to save.” For the alternatives to become competitive, each kilometre travelled by car could have a tariff, she said. “I don't see how we're going to get out otherwise.”

Sharing the road, with more space devoted to pedestrians, bikes and public transit, is also a key solution, she added. “These are travel options that allow us to move more people while using a lot less space than cars, often travelling with a single occupant.”

“Urban development is a really long-term process,” said Wachsmuth. “Most of the time, when we build something, it stays where it is for decades or centuries. That’s true for individual buildings, but more importantly true for the skeleton of urban regions. And what that means is that the decisions we make now, our grandchildren will live with the consequences.”

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Methodology

For the sake of transparency and journalistic integrity, we publish our entire analysis, with the code and data used. Click here to view it.

Do you have data in the public interest that you would like to send us? Write to nael.shiab@radio-canada.ca (PGP key).

Naël Shiab data journalist, Isabelle Bouchard data analyst, Anis Belabbas designer, Melanie Julien desk manager, Mathieu St-Laurent developer, Martine Roy co-ordinator, with the help of Mario Carlucci for the translation