Skinny Streets: New Study Finds Narrower Lanes Improve Traffic Safety

A new national study has revealed that narrower lanes on roads do not increase the risk of accidents and, in fact, can reduce traffic crashes in certain cases.

The new report by researchers at Johns Hopkins Bloomberg School of Public Health sheds light on the impacts of reducing vehicle lane widths in urban areas. The key finding of the study is that there is no evidence narrower lanes are associated with more crashes. Specifically, the research found no significant difference in crashes between streets with 9-foot, 10-foot or 11-foot lanes. However, a change from 9-foot to 12-foot lanes did increase crashes.

“This study highlights the immense potential for saving lives and reducing injuries on our local roads, making it clear that we must prioritize these changes for the well-being of our community,” said Matt Clark, managing partner and attorney at the Law Office of Chain | Cohn | Clark. “Narrower lanes not only can reduce accidents but can also pave the way for more pedestrian and cyclist-friendly streets. It’s a win-win for everyone who uses our roads.”

Researchers analyzed 1,117 street sections across seven diverse U.S. cities, collecting detailed data on lane widths and roadway design characteristics. They then used statistical models to analyze the relationship between lane width and the number of crashes, controlling for factors like traffic volume, speed limits, and roadside design features. The report summarizes the findings of a major research project investigating whether and to what extent existing vehicle lanes can be narrowed without adversely impacting traffic safety.

The findings have immediate policy implications and open the door to safer and more efficient roadways, offering a transformative path for urban planning and transportation policy, traffic safety experts say.

The motivation behind the study is the constant competition for space within urban roadways’ rights-of-way between different modes of transportation. In most American cities, the automobile has historically won this competition, making it challenging to find space for bike lanes and sidewalks. However, with the recent growth in demand for biking and walking, cities are looking for opportunities to reallocate space to these active modes. One potential solution is reducing vehicle lane widths, which can free up space for pedestrians and cyclists. But concerns persist about the traffic safety impacts of this approach.

Interestingly, the study also found the relationship between lane width and crashes varies by speed limit. For streets with speed limits of 20-25 mph, lane widths had no significant impact on crashes. But on streets with 30-35 mph speed limits, those with 10-, 11- or 12-foot lanes had more crashes than streets with 9-foot lanes.

The researchers conclude that, with proper attention to roadway context, lane widths can potentially be reduced without compromising safety. They suggest the best opportunities are urban streets with higher speed limits of 30-35 mph that do not serve as major freight or transit corridors. Narrowing lanes on these roads could improve conditions for biking and walking.

As reported by Chain | Cohn | Clark, the number of people killed on U.S. roads in 2021 — 42,915 — was also 10% higher than the year before, and the largest annual percentage increase since 1975 when such tracking began. At the same time, a nationwide study lists Bakersfield as the No. 2 most dangerous metropolitan area in the United States to be a pedestrian. And even more, Bakersfield lays claim to being No. 1 on the list of worst driving cities, according to a report on the 70 best and worst driving cities in the nation.

In all, this new research provides rigorous evidence that with thoughtful design, lane width reductions can be a win-win, improving walking and biking opportunities while maintaining traffic safety. As cities across the country look to build more sustainable, multimodal transportation networks, this report offers an encouraging path forward. While more research is still needed, these findings suggest revisiting lane width standards offers real promise to support the shifting transportation priorities of the 21st century.