You don’t really have to have been to New York City to know that traffic is bad there. Its soundtrack is car horns, its symbol the taxi, its common language whining about the gridlock on the West Side Highway. But New York traffic has, in fact, gotten worse. The average downtown Manhattan taxi moved at 9.35 mph in 2010, but was inching at 6.8 mph by 2016. The numbers are even worse in the heart of midtown, where the average taxi travels at 4.7 mph—a speed easily matched on foot by any real New Yorker.

Part of the problem is that New Yorkers seem to be driving more than they did a few years ago. The economy has improved, meaning more people are out and about and spending money. Meanwhile, subway service has dropped and bus ridership is down, pushing more locals toward drivers’ seats. (Vehicle registration is up 9 percent in the city since 2012.) And the rise of ride-hailing services like Uber, Lyft, and Via haven’t helped matters—recent research suggests the number of taxi and ride-hail vehicles zipping around downtown Manhattan during weekdays jumped 59 percent between 2013 and 2017, even after accounting for the drop in cab fares.

Now the city finally seems ready to do something about the mess. Something specific, and something other places have made work for them: a congestion charge. Change the price of driving to reflect the activity’s true cost—in time, efficiency, and pollution—and you just might change people’s behavior. Such schemes have succeeded (to various extents) in Sweden, Great Britain, Norway, and Singapore.

In January, a task force convened by the New York state legislature put out a 35-page initial analysis on how to get it done. The group proposes what’s called a cordon charge. It’s a flat $11.52 fee on personal vehicles and a $25.34 fee on trucks entering the busiest section of Manhattan (below 60th Street) from 6 am to 8 pm on weekdays. And they propose those charges be complemented by a $2 to $5 flat fee on taxi and ride-hail trips during those crowded hours, for an extra $355 million in revenue. They estimate that it would cut congestion by 13 percent and generate over $1 billion annually, to be pumped back into the city’s transit system, making the most virtuous of circles.

New York isn’t the only place toying with such ideas. State legislators in California are considering a bill that would allow busy downtowns to implement their own congestion pricing schemes, setting their sights on four unspecified locations in Northern and Southern California. (Expect the LA and Bay Area to make appearances.) And it’s not the first time New York has considered congestion pricing, either. A plan from the Mayor Michael Bloomberg a decade ago went down in a storm of political acrimony.

At heart, this is about behavioral economics. If the city pushes on this lever—say, hiking the cost to drive your own car into Manhattan—what happens? Will people choose the subway? Or will they choose a taxi instead? What if it pulls on that lever, raising fees on taxis and Ubers so that only the very wealthy can afford to take a solo ride in one? Which is better for the city as a whole?

"You have people who are relatively well off in the back seat riding by themselves on the most expensive land in America. It’s a space problem, not a morality problem."

It doesn't help that congestion schemes are supposed to inflict pain. “The object of a congestion charge is for people to cut down on unnecessary trips in their own vehicles, or solo trips in a taxi or car service,” says Sarah Kaufman, who studies transportation technology at New York University’s Rudin Center for Transportation. “It should affect people’s behavior, and it should force them to take mass transit and buses, or at least use a ride-share service like Lyft Line or Via, instead of a solo trip in an Uber or Lyft or taxi.”

But what do you do if none of the levers do what you expect? “What worries me—the reason why I got into looking into this at all—is you could do a full-fledged congestion pricing program and people would not see the effects, because you’re going against the headwind of rapid Uber and Lyft trip growth,” says Bruce Schaller, who served as the city’s deputy commissioner for traffic and planning in the Bloomberg administration, and now runs a transportation consultancy in the city. Schaller’s research addresses a central worry for policy wonks in the midst of the ride-hailing boom: how to make a trip cheap enough to be fair but expensive enough to shift riders off the streets and into public transit.