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July 20, 2026

Traffic calming works, and it's cheap

I wrote a letter to the city asking to make traffic calming the default

I went down a rabbit hole on traffic calming and wrote two pages: Traffic calming works and Traffic calming is cheap. Based on these, I also wrote a letter to Charlottesville's mayor, council, and transportation staff with three main requests: a citywide daylighting program, a Safe Streets Ordinance that makes calming the minimum standard for residential streets, and a standing traffic-calming program. If you live in Charlottesville too, feel free to borrow any of it. Also please let me know if you find any issues.

Some key points:

  • Changing the number on a sign does almost nothing: England's signed-only 20 mph limits changed speeds by 0.38 mph. Physical calming in British 20 mph zones cut them by 9.3 mph.
  • In London's calmed zones, casualties fell about 42%, and deaths and serious injuries to children fell roughly by half. Across London, Toronto, New York, and Oakland, measured cuts to children's pedestrian injuries cluster around 40–50%.
  • Hoboken, NJ—a real American city of 60,000—has not lost a single person to traffic in nine years. Its signature tools: plastic posts, paint, and curb extensions.
  • The prices are so cheap compared to other road-related cost: a daylighting post costs $40 in hardware, a speed hump about $3,000 installed. Speed humps along an entire mile cost about $40,000—roughly 2–3% of what repaving that same mile costs.
  • NHTSA prices one traffic death at $11.3 million—five thousand speed humps. If five thousand humps prevent a single death over their lifetime, the whole program has paid for itself.
  • One year of crashes in Charlottesville (pop. 45,000) costs $23–$30 million in economic terms alone; the measured crash reductions from calming would repay humps on fifty miles of streets in under a year.
  • The carbon cut from the mode shift comes along for free—plausibly more tons per year than the climate programs cities actually budget.

VDOT has an active transportation newsletter

You can sign up to receive periodic updates on the activities of VDOT's Bicycle and Pedestrian Program. HT Tommy Safranek.

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