The relative effectiveness of signal related pedestrian countermeasures at urban intersections—Lessons from a New York City case study

Abstract

ProblemWalking, the simplest form of transportation has many benefits for pedestrians and the society. Yet, pedestrians are a vulnerable group of people and safety concerns are a significant barrier in one's decision to walk. Multiple signal related pedestrian countermeasures have been proposed to promote pedestrian safety. Although the safety impacts of individual strategies have been investigated, their relative effectiveness is little known. Furthermore, those effective in reducing pedestrian crashes may be at odds with motorist safety. PurposeIn this study, we evaluate the relative effectiveness of four signal related pedestrian countermeasures in New York City – increasing the total cycle length, Barnes Dance, split phase timing, and signal installation – and examine potential trade-offs in their reducing pedestrian crashes and multiple vehicle crashes. MethodsWe adopted a rigorous two-stage design that first identifies a comparison group, corresponding to each treatment group, and then estimates a negative binomial model with the generalized estimating equation (GEE) method to further control confounding factors and within-subject correlation. Built environment characteristics are also accounted for. ResultsSet in a large urban area, this study shows trade-offs between improving pedestrian safety and motorist safety. The study finds that two of them – split phase timing and signal installation – are effective in reducing multiple vehicle crashes. Increasing total cycle length is most effective in promoting pedestrian safety, but its effect on motorist safety is insignificant. Among the four examined, Barnes Dance is the second most effective countermeasure in reducing pedestrian crashes and yet, it tends to increase multiple vehicle crashes, though the effect is insignificant. Takeaway for practiceThe findings indicate that selection and implementation of countermeasures for urban intersections should consider the types of conflicts and balance the time for different groups of road users at the intersections so that the countermeasure is targeted to the problem and the improvement of the safety of one group does not compromise the safety of other groups. It is suggested that increasing cycle length be implemented at intersections with wide streets and areas where there is a higher percentage of elderly pedestrians; Barnes Dance is best installed at areas with many pedestrians and a modest amount of traffic; split phase timing is most desirable for locations with turning movements and relatively narrow streets; and installation of new signals depends largely on the volume of pedestrian and vehicle traffic at the intersections as warranted by MUTCD.