Skip to Content
Streetsblog California home
Streetsblog California home
Log In
Speeding

Study: Lowering the Speed Limit … Works To Reduce Speeding

Photo: IIHS

Here's some encouraging news for cities trying to reduce speeding: New research from the Insurance Institute for Highway Safety shows that lowering posted speed limits appears to be effective at reducing driver speeds.

The IIHS study compared speeds before and after Boston lowered its speed limit from 30 mph to 25 mph in January, 2017 — and the results were clear: "Vehicles exceeding 25 mph, 30 mph, and 35 mph all declined at sites in Boston, with the largest reduction in proportions of vehicles exceeding 35 mph," wrote the study authors Wen Hu and Jessica Cicchino.

In fact, the odds of a Boston driver exceeding 35 miles per hour after the speed limit change decreased 29 percent and that a driver would exceed 30 mph declined 8.5 percent (the study offered "odds" because it tracked speeds at specific sites rather than following the same drivers before and after the change).

The study did not examine the impacts on crashes, but prior research shows that slower speeds reduce collisions, said Hu and Cicchino.

IIHS President David Harkey said in a statement that the study should encourage other cities to adopt lower speed limits to reverse the dramatic increases in pedestrian fatalities that have occurred over the last five years. Cities like Seattle, Portland and New York that have lowered their speed limits in recent years.

Two Boston City Council members — Ed Flynn and Frank Baker — have proposed lowering speed limits in the Hub even further, to 20 miles per hour.

Stay in touch

Sign up for our free newsletter

More from Streetsblog California

Incomplete Streets Part 1: How Caltrans Shortchanges Pedestrians

Caltrans has a history of failing to follow its own policies around Complete Streets.

July 15, 2024

Sustainable Transportation Advocates Need to Talk About Sustainable Urban Design

A new book hopes to act as a "magic decoder ring" to our built environment — and a powerful tool to understand how sustainable transportation networks can fit within them.

July 15, 2024

Long Beach Leads in Traffic Circles

Traffic circles aren't quite ubiquitous in Long Beach, but they're around. Riding and walking through the city one encounters circles in neighborhoods rich and poor, new and old.

July 15, 2024

Monday’s Headlines

What transit agencies are dealing with; Oakland's Basic Mobility program is working; Zero emission trains and ferries; More

July 15, 2024
See all posts