Murder by firearm is an urban threat so terrifying that the Bloomberg administration stopped and frisked hundreds of thousands of people ostensibly trying to find guns, district attorneys ran buy-back operations at local churches to get guns off the street and a nonprofit funded by the former mayor sent undercover private investigators to firearms shops and gun shows to expose the shady dealings that fueled the illegal gun trade.

After all, the threat is real: in calendar year 2012, some 239 New Yorkers were murdered with guns.

But in fiscal 2012, 21 percent more New Yorkers (291 of them) were killed in automobile accidents than were slain by bullets.

Six years ago Mayor Bloomberg—during whose term traffic fatalities dropped significantly—announced a plan to to cut the number of traffic deaths in half by 2030. For a mayor who often set ambitious goals, it was pretty modest. During the 2013 campaign, Bill de Blasio promised something far bolder: eliminating traffic fatalities to zero within ten years. He did so in response to organized lobbying by transportation advocates and families of people killed by cars, many of whom had taken up a goal called Vision Zero, a fatality elimination effort that originated in Sweden in 1997.

On Wednesday, de Blasio took a step toward making good on his promise, announcing a working group composed of the NYPD, health department, transportation department and taxi commission to develop a plan for increasing traffic enforcement, improving fifty dangerous corridors and intersections, making more 20 mph zones and going to Albany to get permission to install more speed cameras. The mayor also said that a small set of traffic cameras recently installed would start generating tickets this week. And his police commissioner, Bill Bratton, increased personnel in the Highway Division by 10 percent on the way to a 50 percent increase.

When Bloomberg left office, there were stark warnings that an era of enlightened, ambitious government—the spirit of leadership that had yielded the smoking ban, PlaNYC 2030 and so on—was over. Life under his class-obsessed successor was going to be some dreary Leninist experiment; think Dr. Zhivago, without the pretty girl. De Blasio’s commitment—assuming it’s genuine—to VisionZero is a big middle-finger-out-the-window-while-leaning-on-the-horn at that notion.

If you think targeting traffic death is political softball, think again. “The critical work of redesigning dangerous corridors and intersections, lowering speed limits and increasing penalties for drivers who kill or maim will doubtlessly meet resistance in certain quarters,” said StreetsPAC in a statement yesterday. “The mayor will need to be firm in his resolve. “

Indeed, it may mean wrangling with some community boards and local interests—including our beloved small businesses—over redesigning streets and intersections to be safer. The whole point of VisionZero is that traffic safety requires moral commitment, not cost-benefit analysis. “Under Vision Zero,” reads material from Transportation Alternatives, “safety is prioritized over all other objectives of the transportation system, including mobility.”

It will also mean changing the culture of the police department, which will have to shift focus and resources. Cristina Furlong of Make Queens Safer, who hailed today’s announcement as “historic for the city of New York and a great model for the country,” says that under Bloomberg, “the police department was not on board to make changes to how traffic was enforced. They had other priorities.” And it’s not just the brass: the police union has opposed increases in the use of traffic cameras, preferring that the city hire cops instead.

Finally, it’ll require convincing Albany to give New York City home rule over traffic measures like speed cameras and slow zones. And past attempts to get that authority have failed. In the state Capitol, “there definitely is a windshield perspective among people who aren’t from New York City—legislators from Western and Northern New York who drive cars everywhere,” says Keegan Stephan, an organizer from the transit advocacy group Right of Way. But the opposition isn’t only cultural, it’s also transactional: If the city wants something, legislators from other areas have to feel they’re getting something in return. “It’s horse trading. It’s the political process,” says Juan Martinez, the general counsel at Transportation Alternatives. “At the end of the day, there are things that shouldn’t be fooled around with. Stopping preventable, violent deaths is one of them.”

Given those obstacles, advocates may have to push de Blasio. “I think the fact that we mobilized grieving families across New York City made this happen so quickly,” says Furlong of Wednesday’s announcement. They may need to stay mobilized. What the mayor unveiled on Wednesday was “pretty much everything the community has been asking for,” but “the most important thing is that this is just a first step,” says Stephan, whose organization unveiled a VisionZero Clock just before the inauguration measuring whether the city is on track to de Blasio’s goal. With eleven deaths so far in 2014, it’s not.

If de Blasio delivers the policies he’s promised, there’s another question: Can New York actually reach the target? “The goal is literally to reduce fatalities on our roadways to zero. That is our singular focus,” the mayor said on Wednesday.

Sweden has not reduced its traffic fatalities to zero, but it has cut them in half. The rate of traffic death in Sweden is one of the lowest in the world, and less than a third the per capita rate in the United States.

A 2011 report by Transportation Alternatives said that “over a hundred lives could be saved every year if New York’s traffic fatality rate was the same as many of our peer cities.” A decrease of a 100 deaths would be notable—essentially equal to the progress made against traffic fatalities during the Bloomberg years—but would not get the city to zero. The elusive variable is driver and pedestrian behavior.

Red light cameras and tickets will probably have an immediate effect,” says Furlong. “Changing drivers’ mentality will be more of a long-term thing.”