in areas reduce fatalities, researchers at the Johns Hopkins Bloomberg School of Public Health . The findings go against conventional wisdom that suggests that wider lanes are safer because they leave drivers with more room for error. Based on an analysis of 1,117 streets in the seven cities, the study’s authors believe narrowing the lane width of low-speed city streets would actually reduce traffic-related collisions.

Additionally, making city streets narrower would create more room to build out , which could make streets even safer while also improving quality of life for people who live in the area.

The study found that while you don’t see a significant increase in crashes when a lane is nine, 10 or 11 feet wide, but there’s a 50-percent increase when going from nine feet to 12 feet. Speed limits also appear to be a factor, as they found no significant increase in crashes on streets with 20 and 25-mph limits. Streets with 30 and 35-mph limits have a lot more crashes when lanes are wider than nine feet.

Considering that the leading cause of death in the U.S. for people under 55 is road traffic collisions, this is a pretty big deal. Additionally, pedestrian deaths have been skyrocketing, with the U.S. seeing a 40 percent increase between 2010 and 2018. .

The authors included several policy recommendations:

Street sections with lane widths of 11, 12, or 13 feet in urban settings with a 20–25 or 30–35 miles per hour speed limit that do not serve as a transit or freight corridor should be considered first for lane-width reductions.Decision-makers should set the standard lane width at 10 feet in low-speed urban settings and provide justification for wider lanes.City and state departments of transportation should establish a context-appropriate speed before determining lane width.Engineers and city planners should prioritize inclusive street design rather than driving speed and functionality.City and state departments of transportation could pair lane-width reduction projects with the launch of a lane-repurposing program to add a bike lane or wider sidewalk.

“Lane-width reduction is the easiest and most cost-effective way to accommodate better sidewalk and bike lanes within the existing roadway infrastructure,” Shima Hamidi, PhD, Bloomberg Assistant Professor of American Health and director of the Center for Climate-Smart Transportation at the Bloomberg School, said in a statement. “Narrower lanes ultimately minimize construction and road maintenance and also reduce environmental impacts.”