Understanding Road Diets

An explainer from Momentum highlights the advantages of reducing vehicle lanes in favor of more bike, transit, and pedestrian infrastructure.

1 minute read

April 17, 2025, 11:00 AM PDT

By Diana Ionescu @aworkoffiction


Two people on bikes in red painted bike lane with bus in traffic lane next to them.

Kara / Adobe Stock

An explainer from Momentum Magazine outlines the benefits of road diets, a popular but controversial traffic calming strategy that focuses on reducing the number of vehicle lanes and adding sidewalks and other bike and pedestrian infrastructure to streets.

According to author Ron Johnson, “ The first road diet in the United States was implemented in 1979 in Billings, Montana. Since then, cities like Charlotte, Chicago, San Francisco, and New York have all embraced the model. But it’s not just a design trend—road diets are backed by powerful data and safety results.”

Reducing the number of lanes and average speeds can cut crashes by as much as 52 percent, and slower speeds also mean crashes can be less serious when they do occur.

Although road diet opponents worry about traffic, “Removing travel lanes can actually lead to a reduction in overall vehicle trips—a phenomenon known as traffic evaporation. Some drivers shift to alternative routes or, increasingly, to alternative modes of transport.” Better bike and pedestrian infrastructure incentivizes more people to use those modes, and bus lanes make transit a more reliable option. Road diets thus also lead to reduced carbon emissions and cleaner air. 

“As our cities continue to evolve, road diets offer a cost-effective, data-backed, and scalable way to make them safer, cleaner, and more livable,” Johnson concludes.

Tuesday, April 15, 2025 in Momentum Magazine

portrait of professional woman

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching. Mary G., Urban Planner

I love the variety of courses, many practical, and all richly illustrated. They have inspired many ideas that I've applied in practice, and in my own teaching.

Mary G., Urban Planner

Get top-rated, practical training

Close-up of "Apartment for rent" sign in red text on black background in front of blurred building

Trump Administration Could Effectively End Housing Voucher Program

Federal officials are eyeing major cuts to the Section 8 program that helps millions of low-income households pay rent.

April 21, 2025 - Housing Wire

Logo for Planetizen Federal Action Tracker with black and white image of U.S. Capitol with water ripple overlay.

Planetizen Federal Action Tracker

A weekly monitor of how Trump’s orders and actions are impacting planners and planning in America.

April 30, 2025 - Diana Ionescu

Ken Jennings stands in front of Snohomish County Community Transit bus.

Ken Jennings Launches Transit Web Series

The Jeopardy champ wants you to ride public transit.

April 20, 2025 - Streetsblog USA

Close-up of white panel at top of school bus with "100% electric" black text.

Driving Equity and Clean Air: California Invests in Greener School Transportation

California has awarded $500 million to fund 1,000 zero-emission school buses and chargers for educational agencies as part of its effort to reduce pollution, improve student health, and accelerate the transition to clean transportation.

April 30 - California Air Resources Board

Aerial view of Freeway Park cap park over I-5 interstate freeway in Seattle, Washington at night.

Congress Moves to End Reconnecting Communities and Related Grants

The House Transportation and Infrastructure Committee moved to rescind funding for the Neighborhood Equity and Access program, which funds highway removals, freeway caps, transit projects, pedestrian infrastructure, and more.

April 30 - Streetsblog USA

"No Thru Traffic - Open Streets Restaurants" sign in New York City during Covid-19 pandemic.

From Throughway to Public Space: Taking Back the American Street

How the Covid-19 pandemic taught us new ways to reclaim city streets from cars.

April 30 - Next City