Disaggregate Safety Evaluation for Signalized Intersections and an Evaluation Too1

摘要

The purpose of this study was to evaluate traffic safety at four-legged signalized intersectionsand to develop a spreadsheet tool for identifying high-risk intersections that considered vehiclemovements, left-turn signal phase types, and times of day. The study used data from Virginiaand employed count data models and the empirical Bayes (EB) method to conduct the safetyevaluation. Crash pattern defined by vehicle movements involved in a crash and time of daywere found to be important factors for intersection crash analysis. Especially for a safetyperformance function (SPF), a model specification (Poisson or negative binomial), inclusion ofleft-turn signal types, type of traffic flow variables, variable functional forms, and/or magnitudesof coefficients turned out to be different across times of day and crash patterns.The spreadsheet application tool incorporated the developed SPFs and the EB method.As long as Synchro files for signal plans and crash database are maintained, no additional fielddata collection efforts are required. The developed SPFs and the spreadsheet can be adapted forrecent traffic and safety conditions by applying the calibration methods employed inSafetyAnalyst and the Highway Safety Manual.