Prevalence and Risk Associated with Risky Commercial Motor Vehicle Driver Behavior

Abstract

This report investigates the prevalence and risk of risky driving behaviors among commercial motor vehicle (CMV) operators, with the goal of identifying behaviors and conditions that contribute to safety-critical events (SCEs). The study draws on over 15,000 driving events from three large naturalistic driving studies: the Onboard Monitoring System (OBMS) Field Operational Test, the Canada Naturalistic Driving Study, and the Canada Distraction Study. These datasets provide real-world insight into driver behavior during both baseline (BL) driving events and SCEs. The literature review established a strong foundation by synthesizing decades of CMV safety research. It confirmed that human error is the dominant factor in large truck crashes, with studies such as the Large Truck Crash Causation Study (LTCCS) attributing 87% of crashes to driver behavior. While past research has extensively explored fatigue and distraction, the literature review identified critical gaps in our understanding of other risk factors such as aggressive driving, speeding, and situational judgment failures. Additionally, it highlighted a need for more granular data on the role of environment and temporal variables, including time of day, weather, and roadway familiarity, as they interact with human factors to influence crash risk. The report categorizes the literature surrounding risky driving behaviors into observable errors (e.g., distraction, fatigue), judgment errors (e.g., speeding, improper lane changes), and performance errors (e.g., following too closely, overcorrecting). However, descriptive statistics and regression modeling were used to determine the prevalence, temporal trends, and the association of risky behaviors with SCEs. Error was not used in the analysis because fault was not assigned in the analyzed data. Key findings include: • The majority of SCEs are linked to driver behavior, especially behaviors during complex maneuvers or when the driver was impaired. • Turning and evasive maneuvers were associated with greater SCE risk. • The majority of observed driving maneuvers were classified as “no driver behavior.” However, of the observations with a behavior noted, distraction, drowsiness, driving slower than other traffic, and failing to use a turn signal were the top four observed behaviors in the combined datasets. • In the observations containing distraction or non-driving-related secondary task engagement (NDST), the most prevalent activities were talking/singing, external distraction, adjusting the instrument panel, and hands-free cellphone use. • Reaching, interacting with an electronic device, and handheld cellphone use were among the distraction tasks associated with the greatest risk. • Using a hands-free phone was linked with a lower odds ratio of being involved in an SCE. • Driving slower in relation to other traffic was linked with lower odds of being involved in an SCE; however, further investigation is necessary to quantify the speed difference and context of this finding. • The odds of driving slowly in relation to other traffic, following too closely, and passing on the right appearing in the data were more likely in the 2022–2023 dataset relative to the 2012–2016 dataset. • Changing lanes and negotiating a curve continued to show elevated odds of SCE involvement across the periods between 2012–2016 and 2022–2023.