Skip to Content
Streetsblog USA home
Streetsblog USA home
Log In

Traffic deaths in the U.S. are mounting, reaching more than 40,000 last year, and, according to a recent draft report by the National Transportation Safety Board, speed is the overlooked factor.

The NTSB reported that speeding accounts for about 10,000 deaths a year -- as many as drunk driving. One of the agency's key recommendation was to change the way streets are designed by reforming the "85th percentile rule," a laissez faire approach that seeks to accommodate motorist behavior instead of engineering streets for safety.

It's an argument that Randy LoBasso at the Bicycle Coalition of Greater Philadelphia has been making for a long time. Now the NTSB report is vindicating advocates' critique of the 85th percentile rule, he writes:

The 85th Percentile idea, based on the 1964 “Solomon Curve” says speed limits should be set at what 85 percent of drivers think is healthy. It was created back when the highway system was still young, cars didn’t approach speeds as quickly as they do today, and we didn’t have the sort of statistics and research on traffic dangers we do today.

I have long trashed the 85th Percentile speed approach as outdated and never meant for cities. That hasn’t stopped some -- who feel motor vehicle users should be able to drive as fast as they want -- from lashing out at the Bicycle Coalition’s rational attempts to curb speed and make streets safer for everyone.

Among [the NTSB's] specific recommendations: “Revise traditional speed-setting standards to balance 85 percentile approaches with safe systems approach that better incorporates crash history, safety of pedestrians, bicyclists.”

“In general, there is not strong evidence that the 85th percentile speed within a given traffic flow equates to the speed with the lowest crash involvement rate,” the NTSB says. “Alternative approaches and expert systems for setting speed limits are available, which incorporate factors such as crash history and the presence of vulnerable road users such as pedestrians.”

More recommended reading today: Pricetags shares some insight from transportation economist Todd Litman about the under-appreciated transportation costs of buying a house in the suburbs. Greater Greater Washington considers the potential drawbacks of diverting cut-through car traffic away from residents streets. And the Raleigh Connoisseur reports that a major increase in bus service goes into effect this week in Wake County, following a November vote to increase the local sales tax half a cent.

Stay in touch

Sign up for our free newsletter

More from Streetsblog USA

‘Whether They See It Or Not’: How the ‘Arrested Mobility’ of Black Americans Harms Everyone

"Policy could be the decision to invest in a community, or to disinvest [in that community]. In Black, brown, low-income communities, the policy has been disinvestment."

May 28, 2025

Wednesday’s Headlines Look for a Bailout

Congress's latest Band-Aid for the Federal Highway Trust Fund won't keep it solvent, but it will hurt transit.

May 28, 2025

Doug Gordon Takes on John Mulaney’s ‘Entitled’ and Humorless Anti-Bike Insanity

Why do New Yorkers feel the need to prove their "street cred" by hating on bicycles when it is, in fact, cars that have ruined this city?

May 27, 2025

Car Harms Tuesday: Cars Are Just Ugly

New York has always had businesses and people using its streets for work and play. But it hasn’t always had this many cars, and never before have they been this big.

May 27, 2025

What Transportation Priorities Could Get Cut Under the GOP’s ‘Big, Beautiful’ Budget Bill

Hint: a bloodbath for EVs, reconnecting communities, and environmental reviews.

May 27, 2025

Tuesday’s Headlines Unplugged

Republicans in Washington, D.C. are doing their best to make sure everyone is forced to drive a gas-guzzling, pollution-spewing vehicle.

May 27, 2025
See all posts