Xuesong Wang,Ming Chen
Abstract:While it is generally agreed that traffic safety on urban arterials is closely associated with operational conditions, analysis of theserelationships has been hampered by the absence of continuous measurements of operational variables such as traffic flow. Operationalfeatures of both peak and off peak were examined on a total 176 arterial segments from 23 different corridors within specific regions.These operational data, together with road segment characteristics, (e.g., segment length, number of lanes, median type), were used toconstruct models to estimate crash frequencies under various operational conditions for differing road segments. To account for the spatialcorrelations among the segments along the same corridors, Poisson-lognormal models with a two-level hierarchy under a Bayesianframework were used. Results showed significant relationships among operational conditions, roadway characteristics, and crashoccurrence on these urban arterials. Lower average speeds at the corridor segment level were found to be associated with higher crashfrequencies. The implications of using FCD data to assess operational conditions.