Experimental Microsimulation Modeling of Road Safety Impacts of Bus Priority

The safety implications of the implementation of bus lanes on road corridors remain unclear, given the mixed findings from previous research. Recent research found improvements in road safety resulting from bus priority in Melbourne, Victoria, Australia; however, the causal factors for this effect remain to be explored. In this study, an experimental microscopic traffic simulation modeling approach was adopted to explore the road safety effects of implementation of bus lanes on a representative road corridor in Melbourne. Models compared the traffic conflict patterns of three traffic configurations: mixed traffic (base case, no priority), curbside lane reallocated for buses, and new curbside lane added for buses. For each configuration, the safety performance of the road corridor, including intersection approaches and bus stop locations, was measured with two safety performance indicators: deceleration rate to avoid a crash and crash potential index. The overall results showed that curbside bus lanes reduced conflict occurrences at intersection approaches and bus stop locations, regardless of the scheme design. The results pointed to reductions in rear-end and sideswipe accidents as being a major driver of the reduced risk of a road accident, consistent with the outcomes found in previous research. Bus priority acts to remove bus movements from traffic flows and provides new and separate road space for curbside turning traffic at intersections. These effects of bus priority act to reduce sideswipe and rear-end traffic conflicts and thus to improve road safety. Implications for policy and future research are suggested.