An analytical assessment of freeway service patrol on incident clearance times

Highway service and assistance patrols are widely used to respond to incidents and help manage traffic until conditions return to normal. Traffic Management Centers (TMCs) and other response personnel depend upon on these programs to respond quickly and safely as possible to incidents. This paper examines the impact of highway service and assistance patrols on incident clearance times. The goal of this paper is to measure and understand the impact of Alabama Service and Assistance Patrol (ASAP) along with other influential factors on incident clearance time. Four different datasets were collected, including 18,275 highway crashes collected from the Center for Advanced Public Safety (CAPS) and 7,323 highway incidents recorded by TMCs, as well as the average annual daily traffic (AADT) data and the ASAP coverage area gathered from the Alabama Department of Transportation (ALDOT). The final dataset contains 2,206 crash incidents during the period January 1, 2018 to December 31, 2018. A fully parametric hazard-based duration model has been examined to analyze the incident duration data. Seventeen variables are found to have significant effect on the duration of the incident clearance time, including incident types and characteristics, temporal effects, traffic characteristics, and operational characteristics. The novelty of this paper is the inclusion of additional ASAP coverage area information in the duration models. The contribution of this paper is to provide a better understanding of the factors that contribute to the incident clearance time and to provide a quantitative estimate of the impact of ASAP programs.