The Insurance Institute for Highway Safety reports that in 2015, 3,852 people died in crashes involving large trucks. Sixteen percent of these deaths were truck occupants; 69 percent were passenger vehicle occupants; and 15 percent were pedestrians, bicyclists, or motorcyclists.

IIHS researchers partnered with the University of North Carolina Highway Safety Research Center and the North Carolina State Highway Patrol to investigate factors that affect crash risk for large trucks operated by interstate carriers. This research shows that serious vehicle defects triple the risk of being involved in a crash. According to the report, nearly three-quarters of large trucks involved in serious crashes had vehicle defects that were identified during a post-crash inspection. Eric Teoh, a senior statistician with the Institute and the study’s main author, noted that defects on large trucks are a serious threat to highway safety.

Driver fatigue is another significant contributor to crashes involving large trucks. Long hours behind the wheel and use of the short-haul exemption for federal hours-of-service rules also contributed to crashes, according to the research. Although short-haul drivers must comply with federal rules on work and rest times, they don’t have to record their service hours.

Researchers also found that drivers who operated under a short-haul exemption logged fewer miles per year than other trucks but had a crash risk nearly five times higher than those drivers who did not operate under the exemption. And, short-haul trucks were more likely to have inspection violations.

The new mandate for electronic logging devices (ELDs) – set to take effect in late 2017 – may help increase safety and lower crash risk among the large trucks included the study.

Crash avoidance features may also help reduce crash risk. IIHS states that electronic stability control systems (ESC) and roll stability control show promise to reduce crashes involving large trucks. Electronic Stability Control (ESC) systems will be required on tractor-trailers and buses as of August 2017. They are designed to reduce rollovers and mitigate severe understeer or oversteer conditions that lead to loss of control.