Skip to Content
Streetsblog New York City home
Streetsblog New York City 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I have long trashed the 85th Percentile speed approach as outdated and never meant for cities.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 Durham 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 New York City

Hundreds of Community Groups — From the Far Right to the Socialists! — Demand Daylighting

Two hundred New York City groups from across the ideological spectrum joined calls to ban parking at corners in order to improve safety and visibility, also known as daylighting.

October 24, 2025

OPINION: Canal Street — Not The Vendors — Is the Problem

If Zohran Mamdani becomes mayor — and is true to his vision for a fair, livable city — he will have to take on this long-ignored corridor. Here's how.

October 24, 2025

Vision Zero Cities: Bicycles Are Not Cars So They Shouldn’t Have to Follow the Same Rules

The default in nearly all states is to impose the same traffic rules on bicycles as on motor vehicles even though the needs of cyclists are so different.

October 24, 2025

Friday’s Headlines: Today’s the Day Edition

Mayor Adams's new 15 mph speed limit is officially goes into effect today. Plus more news.

October 24, 2025

Cough, Cough: DEP Considers Largest Ever Exemption Request to City’s Anti-Idling Law

Academy Bus claims no technological alternatives exist for heating and cooling buses without idling. Advocates warn an exemption would "gut" the city's 50-year-old idling ban.

October 23, 2025

Truckers to US DOT: Busways Are Good for Us!

The federal government has obviously lost its trucking mind.

October 23, 2025
See all posts