Analysis of Stability Control Systems for Tractor-Semitrailers

This paper summarizes a study conducted by the University of Michigan Transportation Research Institute (UMTRI) under a Cooperative Agreement between NHTSA and Meritor WABCO to examine the performance of roll stability control systems (RSC), and electronic stability control systems (ESC) for heavy truck tractor-semitrailers. The study is based on the analysis of independent crash datasets using engineering and statistical techniques to estimate the probable safety benefits of stability control technologies for 5-axle tractor-semitrailer vehicles. The conventional approach for assessing the safety benefits of vehicle technologies is to analyze crash datasets containing data on the safety performance of vehicles equipped with the technology of interest. Because the deployment of the stability technologies for large trucks is in its infancy, national crash databases do not yet have a sufficient amount of factual data that can be directly linked to the performance of the technology. Therefore a novel method of examining the potential benefits of these systems was used. Crash scenarios that could likely benefit from the technologies were selected from national crash databases and the probable effectiveness of each technology was estimated. The analysis in this study did not have the advantage of examining representative crash datasets that contain identifiable data from vehicles equipped with the technology. Therefore, the analysis was based on probable outcome estimates derived from hardware-in-the-loop simulation, field test experience, expert panel assessment, and fleet crash data and these methods were used to estimate the safety benefits from the national crash data population.