Crash Estimation at Signalized Intersections Along Corridors: Analyzing Spatial Effect and Identifying Significant Factors

Intersections could be considered as isolated when the distance between them is long because, the influence between them is negligible. Signalized intersections, especially closer ones along a certain corridor, are spatially correlated and will influence each other in many respects. Use of the basic negative binomial regression for correlated crash frequency data leads to invalid statistical inference due to incorrect test statistics and standard errors that are based on the misspecified variance. Generalized estimating equations (GEE) provide an extension of generalized linear models to the analysis of correlated data and can account for the spatial correlation among signalized intersections. In this study, 476 signalized intersections from 41 corridors are selected in Orange, Brevard, and Miami-Dade Counties in Florida. Because the distance between some intersections along some corridors is very long, the intersections along the 41 corridors were divided into 116 clusters. The spatially correlated crash...