Evaluating the Potential Safety Benefits of Electronic Hours-of-service Recorders Final Report

The purpose of the current study was to assess the benefits of installed electronic hours-of-service recorders (EHSRs) on safety and hours-of-service (HOS) violations related to Class 7 and 8 trucks as they operated during normal revenue service. Data were obtained through a third-party vendor that compiled previously-generated compliance data regarding participating motor carriers. Although the final data sets included data from 11 carriers representing small, medium, and large carriers (including a total of 82,943 crashes, 970 HOS violations, and 224,034 truck-years that drove a total of 15.6 billion miles), the data set in the current study was skewed toward larger, for-hire carriers and may not represent the overall U.S. trucking population. After controlling for calendar year, carriers in the data set, onboard safety system (OBSS) status, and long-haul/regional indicator, EHSR-equipped trucks had a significantly lower total crash rate (11.7 percent reduction) and a significantly lower preventable crash rate (5.1 percent reduction) than trucks not equipped with an EHSR. Small sample sizes limited the power to detect a significant difference between the EHSR cohort and the non-EHSR cohort for U.S. Department of Transportation (USDOT)-recordable and fatigue-related crashes. This result is primarily attributed to the lack of sufficient data (in terms of the number of these types of crashes) to be able to detect safety benefits with statistical significance at the observed level. After controlling for year, carrier index, OBSS status, and long-haul/regional indicator, EHSR-equipped trucks had a 53 percent lower driving-related HOS violation rate and a 49 percent lower non-driving-related HOS violation rate than trucks not equipped with EHSRs. The results show a clear safety benefit, in terms of crash and HOS violation reductions, for trucks equipped with EHSRs.