Shrink that street

By: J. David Chapman/December 7, 2023

In November, 2023 a much-anticipated study by Johns Hopkins hospital was released on lane width and safety.

This project is one of the first, and the most comprehensive, efforts to date to address a long overdue built environmental challenge to health: unnecessarily wide travel lanes that are designed to accommodate fast and convenient driving.

This national study investigates the feasibility of narrowing vehicle lanes as the easiest and most cost-effective way to accommodate better sidewalk and bike lane facilities within the existing roadway infrastructure. The study asks whether, and to what extent, we can narrow existing vehicle lanes (for different road classifications) without adversely impacting traffic safety.

Overall, the study found no evidence that narrower lanes (9 feet and 10 feet) are associated with higher number of crashes or increased the risk of vehicle accidents. Quite contrary, the models confirm that in some cases (in the speed class of 30–35 mph), narrowing travel lanes is associated with significantly lower numbers of non-intersection traffic crashes and could actually contribute to improvement in safety. These findings are novel with groundbreaking and have immediate policy/practical implications for identifying streets in each road class as the best candidates for lane width reduction projects.

This is not to say that 9-foot or 10-foot lanes are appropriate and recommended in every situation. In streets in the speed class of >35 mph that serve as a transit or freight corridor, 11-foot lanes would be more appropriate to accommodate oversized trucks. The most immediate candidates for lane width reduction projects are street sections with lane widths of 11, 12, or 13 feet in urban areas in the class of 20-25 mph and 30-35 mph that do not serve a transit or freight corridor.

Studies like this show something that I learned working in municipal government – it is difficult to form a one-size-fits-all policy for cities. Variances and overlay districts are important in developing a comprehensive plan for cities – especially suburban cities with active/productive downtown/urban centers. It appears to me that driving lane width fits in that category. The results of this study, and others, will give city planners, city traffic engineers, and city councils coverage to give narrower lanes and streets a chance in appropriate areas in their cities.

This should create a safer environment for pedestrians and bikers, creating a more engaged/active community in an otherwise auto-centric society.

David Chapman is professor of finance and real estate at the University of Central Oklahoma (jchapman7@uco.edu).