As the 2013 mayoral race gradually shudders to life, the city New Yorkers should look to as a cautionary tale is Toronto. It was in Jane Jacobs’ adopted home town that a progressive mayor, David Miller, laid plans to prioritize pedestrian safety, surface transit, and bicycling, only to see his successor Rob Ford assume office, declare an end to “the war on the car,” and proceed to reverse much of the previous administration’s initiatives.

So when a 2013 mayoral contender calls the last five years of progress toward safer, more sustainable streets the product of a “radical” approach, as Public Advocate Bill de Blasio did in a David Seifman column this weekend, everyone’s ears should perk up.

De Blasio soft-pedaled his words by framing himself as the “incrementalist” to DOT Commissioner Janette Sadik-Khan’s “radical.” But when you consider how large the city is, the innovative street designs that are making it safer to walk and bike in New York have been rolled out in small increments. Less than one half of one percent of NYC street space had been reallocated to pedestrians, bike lanes, and bus lanes as of last summer.

And there is no tide of public sentiment threatening to undo these changes. The public opinion numbers are unambiguous: New Yorkers have a healthy appetite for the portions of progress that NYC DOT has been serving up the past five years. Every time a polling outfit asks people what they think of these projects — from the 2009 Q Poll about the Times Square plazas right up until yesterday’s Times poll about bike lanes — clear majorities say they approve. If the point of incrementalism is to gradually enact progressive policies without provoking widespread hostility to change, then you can call what DOT has been doing “incrementalism.”

While DOT obtains community board approval for the vast majority of these projects, the process of implementing each one can still be rocky at times. By now, the pattern should be pretty familiar: A city street is redesigned to prioritize biking, walking, buses, or public space, and not everyone is pleased with the effect on traffic lanes, parking spaces, or delivery zones. In some cases, acceptance of the project becomes widespread after an initial adjustment period. In other cases, the city makes changes in response to feedback.

The project that de Blasio cited as an example of Sadik-Khan’s “hell or high water” approach, the Kent Avenue bike lane, is actually a good example of the latter. It arose from plans for the Brooklyn Waterfront Greenway, a grassroots transportation project if ever there was one. But when DOT removed parking on Kent Avenue to make room for an interim, painted bike lane, the Williamsburg Hasidic community took issue. So DOT went back and installed a two-way, protected bike lane, converted the street to one-way flow, and restored the parking lanes. Today Kent Avenue is a safe, lively street, a big momentum-builder for the greenway, and a great example of how bike infrastructure can support growing neighborhoods.

If you don’t have the fortitude for any kind of pushback, trial-and-error, or negotiation, then you can just stop trying to improve city streets for transit, biking, and walking. But then you’ll never have a moment like we saw in Jackson Heights last week, where the one-time skeptics of the 37th Road pedestrian plaza came together with Council Member Daniel Dromm to pledge their support and resources to maintain the project. You’ll never produce a success like Kent Avenue or Prospect Park West, never demonstrate how new ways of planning our streets produce tangible safety benefits or better bus service, and never build any kind of constituency to keep moving forward. You might as well declare an end to “the war on the car” and let the status quo — hundreds of annual traffic deaths, buses that crawl along in congested traffic, neighborhoods starved for public space — continue.

In a way, supporters of livable streets should be thanking de Blasio for this eye-opener. No matter how strongly public opinion backs pedestrian- and bike-friendly policies — and every poll indicates that the support is broad — the 2013 race is wide open and there’s just no telling, at the moment, how the next mayor will align on these issues. You can be certain, though, that New Yorkers who want to see continued progress will have to work hard to make their voices heard before next November, and after.