Influence of Lane Width on Bus Crashes

Abstract

Motor vehicle lane width is often reduced to accommodate non-motorized transportation and increase safety for all road users—in many cases from the conventional width of 12 ft to as narrow as 9–10 ft. Although it has not been a significant issue for passenger car drivers, the narrower lanes pose concerns for bus transit operators. This study analyzed data from the Capital Metropolitan Transportation Authority, the public transit provider in the Austin, Texas, area, to evaluate the influence of narrow travel lanes on bus crashes. It included a comprehensive review of literature, interviews with cities and transit agencies, an analysis to determine the correlation between lane width and target bus crashes (sideswipe, fixed-object, and mirror-to-mirror), and an assessment of the impact of a curb or parked car immediately adjacent to the narrow outside lane on bus crashes. The literature review and interview findings support a standard lane width of 11–12 ft for bus routes. The statistical analysis suggested that more target bus crashes were associated with narrower lane widths. A curb or parked car immediately adjacent to the outside lane was problematic regardless of whether the outside lane was less than 12 ft or not. Though narrower lane width could contribute to fewer catastrophic crashes because of the slower speeds, it increases the likelihood of certain bus crashes. Cities and transit agencies should work together to determine lane width to balance the needs of all road users.