Road Safety Benefits from Bus Priority: An Empirical Study

The provision of bus priority is often a major consideration in on-street bus rapid transit design. However, the research is limited and suggests mixed outcomes. This paper explores the impact of bus priority treatments on road safety. An empirical analysis of accident data about bus rapid transit routes in Melbourne, Australia, was conducted. The analysis included an aggregate crash frequency analysis that accounted for statistical effects and a disaggregate analysis that used a safety audit and review of accident types. Overall, bus priority treatments reduced accidents, with a statistically significant reduction of 14.0%. The number of fatal and serious incidents dropped considerably (42 to 29 per annum). The disaggregate safety audit showed reductions in intolerable risks, but some concerns such as interaction of buses and traffic at bus lane setbacks (section of a curbside lane where traffic may enter to make a turn as the bus lane reaches an intersection) and greater pedestrian road-crossing distances caused by bus lanes. However, disaggregate analysis of accident type suggested that bus lanes act as a roadside buffer, reducing collisions with roadside objects and other vehicles. The shifting of stopping buses from the traffic lane into a bus lane was shown to reduce accidents. Bus lanes were thought to increase sight distances at unsignalized intersections and consequently reduce accidents with vehicles to the side. Some treatments were thought to increase traffic density, creating safety benefits through slowed traffic. These findings were statistically robust and suggest that a new perspective on planning for and justifying bus priority measures is warranted.