HMN 2026: How Congestion relief zone results after year one suggest notable road safety benefits

Early trends have pointed to reductions in traffic congestion, travel times, and air pollution within the Congestion Relief Zone (CRZ), the initiative launched by New York City in 2025. Traffic crashes also declined significantly after tolling began, according to a new study by Columbia University Mailman School of Public Health, in partnership with the Yale School of Public Health. However, the program’s impact on injurious and fatal crashes is less clear. The findings are published in the American Journal of Epidemiology.

The CRZ was associated with a substantial decline in overall monthly crash rates, driven largely by reductions in non-injurious and non-fatal crashes. Rates of injurious and fatal crashes—including those involving pedestrians and cyclists—also declined, though less substantially.

“Data just suggest New York City’s Congestion Relief Zone (CRZ) is advancing road safety,” said senior author Christopher Morrison, Ph.D., associate professor at the Yale School of Public Health, who is also affiliated with Columbia Mailman School of Public Health. “Crashes declined after the program began, which means safer streets for everyone who uses the roadways in lower Manhattan.”

The researchers analyzed publicly available collision data from NYC Open Data to assess changes in crash outcomes before and after implementation. NYC Open Data is a free, public database published by New York City agencies.

Launched in January 2025, the CRZ is the first congestion pricing program in the United States. Covering Manhattan south of 60th Street, the initiative aims to reduce congestion and improve travel reliability and quality of life across roughly eight square miles. Vehicles entering the zone are charged between $1.05 and $21.60 depending on vehicle type and time of day.

“Congestion pricing programs have been effective in reducing crash injuries elsewhere in the world,” said first author Nicole Itzkowitz of Columbia Mailman’s Department of Epidemiology. “Cities such as London and Stockholm have seen decreases in road traffic injuries following similar policies, and we wanted to know if we would see the same results in NYC. However, without the additional traffic calming measures often found in European cities, reducing traffic volume in NYC may allow drivers within the CRZ to travel faster, potentially increasing crash risks.”

In the year before implementation, the CRZ averaged 549 crashes per month, compared with 502 in the control zone. In the six months after implementation, averages fell to 496 crashes per month in the CRZ and 492 in the control zone.

“Our findings suggest that while the introduction of the CRZ is associated with fewer overall crashes, the program’s benefits may be less pronounced for injurious and fatal crashes—the outcomes with the greatest public health implications,” said Morrison. He noted that faster vehicle movement within the zone may partly explain the weaker effects on severe crashes, since vehicle speed is strongly linked to injury severity.

The authors say congestion pricing alone is unlikely to achieve the city’s goal of eliminating traffic deaths and serious injuries. New York City’s Vision Zero—the citywide initiative launched in 2014, is aimed at eliminating all traffic-related deaths and severe injuries by focusing on redesigning streets, lowering speed limits, expanding automated enforcement, and increasing public awareness. According to Itzkowitz and Morrison, additional measures—such as red-light cameras and traffic calming by physically forcing drivers to slow down, thus reducing aggressive driving—may be needed to complement the CRZ and further improve road safety.

The researchers conclude that additional study is needed to better understand how vehicle speed and traffic density influence crash outcomes following CRZ implementation, and to understand how the program is affecting crashes in neighborhoods just outside the Zone.

Co-authors are Leah E. Roberts, Andrew Rundle, Kathryn G. Burford, Siddhesh Zadey, Adam Whalen and Brady Bushover, Columbia Mailman School; Guohua Li, Columbia Mailman School and Vagelos College of Physicians and Surgeons; and Joyce C. Pressley, Columbia Center for Injury Science and Prevention.

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