Reducing vehicle lane widths has been proposed as an effective strategy to decrease vehicle speeds and enhance road safety. However, the safety benefits of narrower travel lanes remain a topic of debate due to mixed findings in the literature. This study examines the relationship between lane width, vehicle speed, and crash occurrence to comprehensively understand their impact on road safety and transportation planning. Using data from 320 urban arterial sections in Utah, the analysis reveals that narrower lane widths are associated with reduced vehicle speeds. For every additional foot of lane width, 85th and 95th percentile speeds increase by 1.012 mph and 1.088 mph, respectively. Furthermore, injury crash modeling indicates that a one-foot increase in lane width is associated with a 38.3% increase in the odds of an injury crash on a roadway section. These findings contribute to the growing evidence supporting the implementation of narrower lane widths as a strategy to improve road safety, foster multimodal infrastructure, and promote sustainable urban transportation systems. We recommend that UDOT adopt a minimum lane width of 10 or 11 feet for arterials in highly urbanized areas, such as downtowns and major activity centers.

This study investigates the relationship among lane width, velocity, and accident rates to enhance understanding their impact on road safety and transportation. Analysis of data from 320 urban arterial sections in Utah indicated that narrower lane widths can improve road safety. Reduced vehicle speeds were related to narrower lanes on urban arterials, which did not result in increased collision rates. Reducing one foot in lane width led to an average speed decrease exceeding one mph. Additional factors influencing speed on urban arterials encompass the number of lanes, the existence of medians, on-street parking, roadside obstructions, and block length. Safety modeling indicated no clear correlation between lane width and total crash frequency per mile. Injury crash rates positively correlated with lane width and speed, suggesting that broader lanes and elevated speeds augment the probability of injury crashes. Additional critical elements affecting crash statistics comprised the number of lanes and the Average Annual Daily Traffic (AADT) per lane (in thousands). The study endorses the reduction of lane widths as a viable approach to augment road safety and boost urban transportation infrastructure. The results provide essential direction for policymakers and transportation authorities aiming to enhance road safety and efficiency.