Leading pedestrian intervals treating the decision to implement as a marginal benefit–Cost problem

To improve the safety of people walking at particular signalized intersections, traffic signal engineers may implement leading pedestrian intervals (LPIs) to provide pedestrians with a walk signal for a few seconds before the parallel vehicular green indication. Previous beforeandafter studies and simple economic analyses have indicated that LPIs are lowcost tools that can reduce vehicle–pedestrian conflicts and crashes at some signalized intersections. Despite this evidence, municipalities have little guidance for when to implement LPIs. A marginal benefit–cost framework is developed with quantitative metrics and extends the concept of traffic conflicts and marginal safety–delay tradeoffs to analyze the appropriateness of implementing an LPI at specific signalized intersections. The method provides guidance to help quantify the probability of a conflict occurring and direction on whether to implement an LPI at a given location from macroscopiclevel inputs, including number of turning movements, crash data, and geometry. A case study with sample data indicated that an LPI was costeffective for the scenario presented.