title: Comparison of Multivariate Poisson lognormal spatial and temporal crash models to identify hot spots of intersections based on crash types.
abstract: Most of the studies are focused on the general crashes or total crash counts with considerably less research dedicated to different crash types. This study employs the Systemic approach for detection of hotspots and comprehensively cross-validates five multivariate models of crash type-based HSID methods which incorporate spatial and temporal random effects. It is anticipated that comparison of the crash estimation results of the five models would identify the impact of varied random effects on the HSID. The data over a ten year time period (2003-2012) were selected for analysis of a total 137 intersections in the City of Corona, California. The crash types collected in this study include: Rear-end, Head-on, Side-swipe, Broad-side, Hit object, and Others. Statistically significant correlations among crash outcomes for the heterogeneity error term were observed which clearly demonstrated their multivariate nature. Additionally, the spatial random effects revealed the correlations among neighboring intersections across crash types. Five cross-validation criteria which contains, Residual Sum of Squares, Kappa, Mean Absolute Deviation, Method Consistency Test, and Total Rank Difference, were applied to assess the performance of the five HSID methods at crash estimation. In terms of accumulated results which combined all crash types, the model with spatial random effects consistently outperformed the other competing models with a significant margin. However, the inclusion of spatial random effect in temporal models fell short of attaining the expected results. The overall observation from the model fitness and validation results failed to highlight any correlation among better model fitness and superior crash estimation.
authors.affiliation: Department of Civil Engineering, California State Polytechnic University, 3801 W. Temple Ave., Pomona, CA 91768, United States. Electronic address: wcheng@cpp.edu.
authors.forename: Wen
authors.initials: W
authors.lastname: Cheng
authors.affiliation: Department of Civil Engineering, California State Polytechnic University, 3801 W. Temple Ave., Pomona, CA 91768, United States. Electronic address: gurdiljotg@cpp.edu.
authors.forename: Gurdiljot Singh
authors.initials: GS
authors.lastname: Gill
authors.affiliation: California Department of Public Health, PO Box 997377, MS 0500, Sacramento, CA 95899-7377, United States. Electronic address: rkmdasu@gmail.com.
authors.forename: Ravi
authors.initials: R
authors.lastname: Dasu
authors.affiliation: Department of Civil Engineering, California State Polytechnic University, 3801 W. Temple Ave., Pomona, CA 91768, United States; School of Transportation and Logistics, Central South University of Forestry and Technology, Changsha, Hunan 410004, PR China. Electronic address: mxie@cpp.edu.
authors.forename: Meiquan
authors.initials: M
authors.lastname: Xie
authors.affiliation: Department of Civil Engineering, California State Polytechnic University, 3801 W. Temple Ave., Pomona, CA 91768, United States. Electronic address: xjia@cpp.edu.
authors.forename: Xudong
authors.initials: X
authors.lastname: Jia
authors.affiliation: Department of Civil Engineering, California State Polytechnic University, 3801 W. Temple Ave., Pomona, CA 91768, United States. Electronic address: jiaozhou@cpp.edu.
authors.forename: Jiao
authors.initials: J
authors.lastname: Zhou
mesh_terms: D000063:Accidents, Traffic / Q000706:statistics & numerical data*; D001499:Bayes Theorem; D002140:California; D002947:Cities; D006801:Humans; D015233:Models, Statistical; D016012:Poisson Distribution; D012449:Safety / Q000706:statistics & numerical data*; D017751:Safety Management / Q000379:methods*; D062206:Spatial Analysis
keywords: Crash count models; Cross validation; Hot spot identification; Multivariate; Spatial correlations; Temporal correlations