These big cities cut back cars. This is what happened next

Cities around the world trying to limit driving have faced objections — namely that the measures would limit personal freedom, cost too much, destroy commerce or have negligible effects on air quality.

Now the first data from these experiments in New York, London and Paris is trickling in. They offer some clues about whether cutting speed limits, charging traffic for entering a city center and penalizing drivers of the most polluting cars can reduce congestion and improve air quality, without causing too much disruption.

These lessons are helpful because cities, where problems with traffic and poor air quality are frequently more severe than in less urban areas, are often moving more quickly in restricting vehicle emissions than countries or states. In Europe, cities are outpacing laws and national regulations to cut traffic pollution, according to the think tank Transport & Environment. In total, 35 cities have committed to introducing “zero emissions zones” — where diesel and gasoline-powered vehicles will be banned.

Still, early results from some cities show reducing traffic is not enough. Take Oslo, which has pioneered lower speed limits, car-free zones and improvements to public transport, walking and cycling. Norway’s widespread adoption of electric cars has also helped reduce smog. But the city still suffers from high levels of particulate pollution from tire wear, wood-burning stoves and dust from gravel and salting on icy roads.

While restricting fossil-fueled vehicles won’t solve those problems, there is evidence that it helps clean the air and has other benefits too.

Here’s what policy makers and city dwellers can learn from other early adopters.

New York

The city introduced a policy on Jan. 5 charging cars up to $9 a day to enter certain parts of Manhattan. Travel time data from the first three months of the charging zone suggests commuting times are down on some of the busiest routes, in particular the bridges and tunnels that connect Manhattan with New Jersey, Brooklyn and Queens.

A site run by student brothers Joshua and Benjamin Moshes has been tracking travel times based on Google Maps traffic data on various routes affected by the New York congestion pricing since the policy was introduced in January. They found travel times have also dropped during weekends, while there’s been little change on other routes going from one part of Manhattan to another. That suggests people are choosing to take public transport or cutting out less urgent travel, they say.

In Boston and Chicago, which the Moshes use as a control, traffic levels have not changed significantly. A separate review released in January by the traffic data provider Inrix echoes their findings, while a Bloomberg analysis released around the same time found fewer private cars and more taxis on the road.

Paris

Mayor Anne Hidalgo introduced 50kph (30 mph) speed limits on the city’s outer ring road in October, despite opposition from France’s transport minister and conservative opponents.

A report from the city’s urban planning department found that the new, lower speed limit, introduced on Oct. 1 last year, has already had some positive effects. In the following five months, air quality improved by 12% and traffic accidents dropped by 17%, compared to the same period in the previous year. There are also signs that congestion is lower.

Hidalgo, who has said she won’t seek re-election next year, isn’t finished with her plans to reduce car traffic and encourage walking and cycling in Paris. In addition to charging higher parking fees for SUVs, the local government has reserved one lane on the main highway encircling the city for public transport and carpooling. Her office also banned motorized through-traffic from the center of the city in November. Local workers, residents and taxis are still able to drive into the zone, but anyone passing through to go somewhere else will be fined €135 ($153) once enforcement begins.

London

The city’s ultra-low emission zone has been in place for over five years. The restrictions, which place a daily charge on driving old gasoline or diesel vehicles, initially covered a small area of the city center. It was subsequently expanded to cover an almost 600 square mile area, making it the largest in the world. London has had a separate congestion charging zone, which means almost everyone who drives into the city’s core must pay, since 2003 (electric cars are exempt until December this year).

When London mayor Sadiq Khan announced the expansion in 2022, the decision was met with warnings that high street shops would wither away and small businesses would struggle to survive.

ULEZ, as the area is known for short, became a contentious topic in local elections, and Khan’s opponent, from the right-wing Conservative Party, made it a central part of her pitch to voters in the mayoral election last year. (Khan won).

In March, the mayor’s office released data suggesting that ULEZ had a positive impact on air quality, while causing little disruption to shops in the outskirts of London, an area which was only included in the zone in August 2023. In particular the change has cut emissions of nitrogen oxides, air pollutants linked to lung problems, asthma and inflammation, by between 33% and 39%, while footfall and spending in shops has not dropped, according to data from Mastercard Inc.

Almost 97% of vehicles driven within the zone are now compliant with the emissions standards, the report said. Vans, which were much more likely to be caught up by the changes, have been slower to switch, but over 90% are now compliant, compared with just 12% in 2017, before the zone was introduced.

“Everyone in the capital is now breathing cleaner air because of ULEZ,” said Christina Calderato, Transport for London’s director of strategy, commenting on the report.