Economists and transportation experts will tell you there’s only one proven policy that reduces traffic congestion. The only question is whether the public has the palate for it.

In Boston, the question is particularly pressing.

According to a study released this month, Boston drivers spend the highest percentage of their time stuck in traffic compared to any other city in the country. INRIX, a transportation analytics firm, found that drivers in Boston spent 14 percent of their drive time in congestion in 2017. The city was also tied with San Francisco for highest rate of time in congestion during rush hour at 23 percent.


According to the study, the combined direct costs (such as wasted fuel and time) and indirect costs of sitting in all that traffic amount to $2,086 per driver each year.

“If you’re a household of two drivers, you’re losing $300 a month in traffic congestion,” said Chris Dempsey, the director of the advocacy coalition Transportation for Massachusetts. “Think about what $300 a month would mean for the average household.”

Traffic woes are hardly a new issue in Boston, where the daily congestion has taken its toll on commuters and local businesses alike, as well as the city’s perceived ability to attract future businesses. In some ways, Boston’s traffic is a good thing, in that it is an indicator of healthy economy and a growing population. However, like the city’s resulting housing crunch, it’s a problem that can worsen if left unaddressed.

“The traffic we have is emblematic of a place where it’s very desirable to live, but it’s also a result of our failure to get our public policy and our politics right on transportation,” Dempsey said.

What have other places with bad traffic done?

Boston isn’t the first or only metropolitan area to face traffic issues, as INRIX’s full 2017 global traffic scorecard attests. However, there are a few cities that have dramatically reduced their traffic through a policy called congestion pricing.


“Conceptually and empirically, it’s the only thing that’s ever been shown to reduce traffic congestion,” Mike Manville, a UCLA professor and Massachusetts native who studies transportation, recently told Commonwealth magazine.

There are several different forms of congestion pricing, but all of them follow the same fundamental principle: Charge a fee to drivers in the most high-traffic areas in order to incentivize them to get off the road — or at least drive at a different time.

“It causes people to realize the costs they’re imposing on others,” says Harvard professor Jose Gomez-Ibanez, who has studied the effects of congestion pricing in other cities.

Congestion pricing was first implemented in Singapore, where the government began charging drivers to enter the city-state’s two-square-mile central business area in an attempt to address widespread gridlock in the 1970s.

Signs indicating London congestion charges that drivers pay for entering the capital’s central areas. —Tolga Akmen / Getty Images

More recently, zone-based congestion pricing has resulted in sustained, double-digit percentage decreases in traffic in London and Stockholm, where the policy was tested and then implemented in the mid-2000s. London enforces a relatively steep £11.50 daily charge for driving into the central part of the city between 7 a.m. and 6 p.m. on weekdays. Stockholm, meanwhile, implemented a lesser, more incremental charge — about $1.25 to $2.50 on weekdays depending on the time of day — to enter the city. Despite initial resistance, the policy has been increasingly embraced by residents in the two European cities, according to polls. And in addition to dramatic reductions to overall and peak traffic, the two cities also saw an increase in people taking public transit.

How does it actually work?


To understand how congestion pricing is effective, it’s perhaps first important to understand the economic perspective of traffic. First, congestion results when and because roads are underpriced, according to Manville.

“We have meters for our gas, for our heating oil, for our electricity, and it should tell us something that we don’t twice a day have blackouts,” he told Commonwealth. “We don’t twice a day have our heat shut off. We don’t twice a day see our toilets back up. We do, twice a day or more, see our road systems fail from overuse, and that’s because we give it away for free.”

Second, traffic is something economists call a “nonlinear function,” which means that congestion can get exponentially worse with each additional car.

“Every car after [a road’s] capacity level actually creates more traffic than the car that came before it,” Dempsey said. “That’s really bad, and that’s why we go from like a clear road to gridlock relatively quickly.”

The flip-side of the nonlinear nature of congestion is that it means taking a small number of cars off the road can make a meaningful difference. As Dempsey put it, it’s why driving into work on a Friday morning in the summer is so much better than doing the same drive on a Tuesday.

“When you’re way up that exponential curve, you only have to get a small number off to drop the traffic way down,” he said. “The rule of thumb that economists use on this is if you can get 5 percent of the cars off the road, you can reduce your traffic by 20 percent.”

What are the concerns?

One point of consideration when it comes to any form of congestion pricing is equity, since it is effectively a regressive tax.

“Low-income people may not be able to afford congestion tolls,” Gomez-Ibanez said. “They may not have job flexibility to change hours.”

In a vacuum, lower income people may disproportionately bear the costs of the fee itself. But proponents of the policy have argued that they may also disproportionately benefit from the policy, since lower-income earners are more likely to use public transportation, such as buses, which are hampered by congestion. According to Dempsey, jurisdictions that have raised revenue from congestion fees have often taken that money and “plowed it right back into congestion mitigation in that corridor,” including improving the reliability of trains and buses in the area.

“The big problem with buses is that they get stuck in traffic,” he said. “In a world where we’re doing a better job of managing our roads and you don’t have as much traffic, then the bus becomes a much more desirable and a much more efficient way to get around.”

Others have proposed using congestion fee revenues to finance a sales tax cut or a “congestion dividend” to local residents, which could offset the regressive effects of the policy.

Another big obstacle to a straightforward congestion zone in Boston would be the actual logistical implementation. Unlike Stockholm or Manhattan, the city has countless different entry points, which would make enforcement of the zone (whether it be by special licenses, gantries, or toll sensors) difficult and expensive.

“The geography is not quite as favorable,” Gomez-Ibanez said of Boston.

He also noted that Singapore, London, and Stockholm also benefited from reliable, highly used public transportation systems, which made congestion pricing more effective and palatable.

Would it be feasible here?

Zone-based congestion pricing has yet to be implemented in the United States. Despite its effectiveness around the world, Dempsey says that even progressive cities like Boston aren’t politically there yet.

“If you just go out and say, ‘Hey, we’re going to start putting up toll gantries all around the city and people will have to pay money,’ that’s like literally the least popular public policy you could ever propose,” he said. “It just kills the conversation.”

Noting the general hostility against taxes or fees in the United States, Gomez-Ibanez concurred: “The politics of congestion pricing are tough.”

For example, when former City Councilor Paul Scapicchio proposed a congestion charge for downtown Boston in 2005, he was reportedly widely ridiculed, even by The Boston Globe‘s editorial page.

“Boston officials should not assume that the capital of Massachusetts matches up with the capital of England as a draw for corporations and their employees,” the Globe wrote, adding that it was “hard to imagine a package sufficient to drive away fears over lost business and outraged visitors who could be fined simply for making a downtown day trip.”

But the traffic problem isn’t going away. Perhaps ironically, the Globe‘s editorial page just endorsed a more incremental form of congestion pricing, which Dempsey describes as “smarter tolling.”

The Tobin Bridge heading into Boston in 2014. —Suzanne Kreiter / The Boston Globe file

Smaller steps

Forty different jurisdictions in the United States have reportedly implemented tolls on certain high-traffic roadways that fluctuate based on time or congestion — as opposed to the zone-based congestion pricing model. With higher fees during the peak travel times like the morning and afternoon rush hours, so-called dynamic tolling incentivizes drivers to either shift the time that they travel or utilize alternatives.

Despite generating a few eye-popping headlines, transportation experts say the policy is the best bet to rid urban freeways from costly congestion. Dempsey says it’s worth testing in Boston on roads that are already tolled, such as the Tobin Bridge. Instead of the current flat $1.25 charge at all times of day, he proposes state officials charge less during non-peak hours and more during rush hour.

“That might get 2 or 3 or 5 percent of people to decide to shift their trip,” Dempsey said. “If we can do that, we’re going to see a traffic reduction of 5 or 7 or 10 percent.”

Even the higher rush hour charges may seem more appealing for drivers who benefit from the breezier ride — unlike the current situation, in which drivers on the Mass. Turnpike pay a toll for no noticeable benefit compared to those who drive on I-93 for free. Dempsey says it’s a “pro-driver policy” in the sense of getting cars moving faster.

“If we tolled in a smarter way, then the drivers would actually see the benefit of that tolling, and I think we would all be much more willing to pay the toll,” he said.

With tolling gantries hanging above the Tobin Bridge and the Turnpike, Dempsey says the technology is already there. He at least wants to see MassDOT test the policy to show it works.

“We know this is a tool that has worked well in other places,” he said. ” The technology is actually the easy part. The hard part is the change we need in our conversations.”