Simultaneous equation modeling of freeway accident duration and lanes blocked

Publication date: July 2015 Source:Analytic Methods in Accident Research, Volume 7 Author(s): Yi-Shih Chung , Yu-Chiun Chiou , Chia-Hua Lin Unbiased estimates are crucial to providing correct information that is required in accident management. Whereas earlier studies have proposed various approaches to reduce the adverse effects of unobserved heterogeneity, this study proposes accelerated failure time (AFT) models of accident duration with flexible distributions of the error term and the frailty parameter. A two-stage residual inclusion (2SRI) method for identifying the effects of endogenous variable in the nonlinear AFT models is adopted. The Taiwanese freeway accident databases were used to evaluate the applicability of the proposed approach. The results reveal that AFT models with a non-monotone Log-logistic error term distribution and a gamma frailty parameter distribution outperformed those with other assumed distributions. Number of lanes blocked was found as a significant endogenous variable to accident duration; the endogenous variable effect, if not accounted for or accounted by traditional two-stage least squares estimators, would underestimate the effect of the number of lanes blocked on accident duration.
Source: Analytic Methods in Accident Research - Category: Accident Prevention Source Type: research