Freeway Incident Management: Analyzing the Effectiveness of Freeway Service Patrols on Incident Clearance Times

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Traffic incidents caused by vehicular crashes, roadway construction, disabled and abandoned vehicles, extreme weather conditions, and planned special events, comprise about half of all traffic congestion. As the duration of traffic incidents increases, it increases the probability of severe congestion, secondary crashes, traveler delay, travel time variability, emissions and fuel consumption, air pollution, economic and social inadequacy, as well as reduces the roadway capacity and the reliability of the whole transportation system. Freeway service patrol (FSP) programs have been considered as an effective Traffic Incident Management (TIM) program for reducing incident duration and thereby minimizing the adverse effects of traffic incidents. The overarching goal of this dissertation is to assess the impact of Alabama Service and Assistant Patrol (ASAP) program based on a unique compiled dataset. The specific objectives are: (1) to merge and match four different datasets, including response data, crash data, traffic volume data and ASAP data; (2) to identify the explanatory variables of incident clearance times with an emphasis on the ASAP coverage area information; (3) to assess duration data using hazard-based duration models with the aim of determining which modeling method best fits the data; and (4) to verify the spatial transferability for the impact of ASAP coverage area. To achieve the research objectives, this dissertation is divided into three parts. The first part describes the Weibull distribution with gamma heterogeneity in identifying the explanatory variables of incident clearance times. The second part compares two advanced econometric modeling methods (random parameters and latent class) in identifying which modeling method best fits the data. The third part employs random parameters modeling method to verify the spatial transferability of the impact of the ASAP program across the state. Ultimately, this dissertation presents a data-driven assessment of the ASAP program in the state. The distinctive contribution of this research is to provide a better understanding of the significant variables that influenced the freeway incident clearance times. The findings of this dissertation are anticipated to assist TIM agencies in formulating and implementing strategic plans to reduce freeway incident clearance times while maximizing the advantages of the ASAP program.

Electronic Thesis or Dissertation
Crash and Incident Data, Freeway Service Patrol, Hazard-based Duration Models, Road Safety, Spatial Transferability, Unobserved Heterogeneity