Published in 2006
Many state departments of transportation (DOTs) operate safety service patrols (SSPs) as part of their incident management programs. The primary objectives of SSPs are to minimize the duration of freeway incidents, restore full capacity of the freeway by removing incidents faster, and help reduce risks to motorists and response personnel. To become and remain competitive for funding, freeway SSPs must be able to quantify and articulate their value, relative to cost. Although estimates of the benefits of these programs have been quantified in other areas of the United States, the Virginia Department of Transportation (VDOT) does not have a documented methodology for quantifying the benefits of its SSP programs. This study sought to develop such a methodology. The scope of the study involved a state-of-the-practice literature review, the development of the methodology, and an application of the methodology to VDOT's Northern Virginia (NOVA) SSP program as a case study. The case study also included an examination of the NOVA SSP operations and a performance analysis of its incident responses. To quantify the benefits attributable to SSP programs, a methodology was developed for determining incident durations with and without SSP. This methodology was applied to the NOVA SSP, and the results were used as inputs into the Freeway Service Patrol Evaluation model, developed by the University of California-Berkeley, to estimate delay, fuel consumption, and emissions savings garnered by NOVA SSP deployments. The study found that 75 percent of SSP-recorded incidents are cleared in 15 minutes and approximately 23 percent are cleared in from 15 to 90 minutes. Further, the support of the NOVA SSP reduced the average incident duration by approximately 17 percent. This reduction contributed to an overall NOVA SSP benefit-to-cost (B/C) ratio of 6.2:1. The study recommends that all VDOT SSP programs track performance to measure and monitor trends. The study further recommends that SSPs conduct yearly benefit-cost evaluations using the Freeway Service Patrol Evaluation model and the associated methodology developed in this study for determining incident durations with and without SSP.
Michael J. Demetsky, Ph.D.
Last updated: November 27, 2023