Jeff Kenworthy is professor in sustainable cities, Curtin University, Perth, Western Australia. He is the co-author of The End of Automobile Dependence: How Cities are Moving Beyond Car-Based Planning.

Toronto has a major opportunity to consolidate its global reputation as a first-class city by removing the Gardiner Expressway. The determination by the city's current mayor to keep this piece of outdated auto-era infrastructure is troubling for the future of Toronto.

The world has entered a new era with the peaking of car use from around 2004 in most developed nations, with large increases in transit use, walking and cycling. Growth in GDP has decoupled from growth in car use, so cities can now progress both economically and in liveability with less car use. City spaces can become more attractive as people places. And the global knowledge economy likes people-intensive locations, so it's good economics.

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Many cities have seen the value in removing key pieces of freeway on their waterfronts. Portland, Ore., removed the Harbor Drive Freeway and created Tom McCall Waterfront Park. San Francisco removed the Embarcadero Freeway and reconnected its centre with its waterfront. In 2012, the mayor of Paris, Bertrand Delanoë, won a long fight to convert part of the Georges Pompidou Expressway along the Seine into a pedestrian zone.

The best example is the Cheonggyecheon Expressway in Seoul, 5.8 kilometres of which was torn down in the heart of the city to resurrect a river buried under roads carrying about 120,000 vehicles a day. The urban heat island has reduced by about 3 C and the average traffic speed in the city increased by 1.2 km/h. The people of Seoul now have a beautiful green river corridor along which to promenade and enjoy city festivals.

The interesting thing for Mayor John Tory is that the then-mayor of Seoul, Lee Myung-bak, built his political future on this landmark freeway-removal project. He became South Korea's president in December, 2007, when the New York Times wrote: "The man chosen as South Korea's next president in Wednesday's election owes much of his victory to a wildly successful project he completed as this city's mayor: the restoration in 2005 of a paved-over, four-mile stream in downtown Seoul, over which an ugly highway had been built during the growth-at-all-cost 1970s. The new stream became a Central Park-like gathering place here, tapped into a growing national emphasis on quality of life and immediately made the mayor, Lee Myung-bak, a top presidential contender."

All these large freeway closings are possible because the predicted traffic does not occur. Traffic engineers think of traffic as a liquid, which retains its volume and will simply flood over everything if its channels are removed. But traffic has behaved repeatedly like a gas, whose volume contracts when space is removed. The majority of traffic simply disappears. There are now innumerable examples of this worldwide.

Toronto is a magnificent city, admired by so many around the world. It already demonstrates some very positive transportation features, which my comparative urban research has quantified. For example, rather than being the overwhelmingly car-dependent environment that Mr. Tory portrays when talking about the Gardiner Expressway, the Greater Toronto Area has less than half the per-capita car use of an average American city. Its transit use per capita is 2.3 times higher.

Toronto is poised at an advantageous and opportune time to capitalize on the trend away from car-based planning and thinking throughout the world's cities.

The jury is no longer out on the correct decision for Toronto to make. Toronto has much to gain by removing the Gardiner Expressway. Mr. Tory has more to gain politically by supporting the project. He has a choice. He can resign himself to the dustbin of history, as yet another unimaginative leader who opted for a business-as-usual approach of promoting destructive freeways. Or he can become a member of a distinctive group of successful politicians who have built their political careers on taming the automobile by creating beautiful city spaces.

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In the end, the tortured politics are quite unnecessary. It is really an easy choice.