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Why Speed Kills Cities

U.S. cities are dropping urban speed limits in an effort to boost safety and lower crash rates. But the benefits of less-rapid urban mobility don’t end there.  
Slow and steady wins the urban mobility race.
Slow and steady wins the urban mobility race.Madison Johnson/CityLab

“Slow the hell down.” That’s the message New York City Mayor Bill De Blasio delivered on Twitter as he announced the revival of the city’s speed camera program. The cameras went live in July with expanded hours, issuing hefty tickets to any driver who creeps above 36 miles per hour—that’s 11 mph above the city’s 25 mph posted limit—in 750 school zones throughout the city’s five boroughs.

New York City, which has been struggling to get its Vision Zero safe-streets program back on track after a 2019 surge in cyclist deaths, has also been the most prominent American city to test the idea of a “neighborhood slow zone”—a relatively infrastructure-light path to safer streets that drops speed limits to 20 mph on interior roads in residential areas. It will soon be joined by Philadelphia, where the inaugural designation of two slow-speed corridors, modeled after the New York City program, was overwhelmed with more than two dozen applications.