By Eric Teoh, Director of Statistical Service, Insurance Institute for Highway Safety
The commercial motor vehicles (CMV) industry is a key component of America’s economy, transporting over $700.4 billion worth of goods each year. While the safe operation of CMVs clearly has economic benefits, perhaps more important is that those CMV drivers are also entrusted with the lives of those they transport and those they encounter on our nation’s roads. Due to the size and weight of many CMVs, there is an inherent risk involved in their operation. As such, it is important for all stakeholders to take actions that improve CMV safety. Of note, data collection is crucial in enhancing the safety of the commercial motor vehicle industry by enabling monitoring of driver behavior, vehicle maintenance, and compliance with safety regulations.
A key reason for accurate and comprehensive record-keeping is to hold drivers who operate these large vehicles accountable for bad driving behaviors. Our justice system plays a critical role in ensuring that the drivers and companies operating these large vehicles obey the rules of the road and the rules of their commercial operation. Enforcing these rules translates into real-world reductions in crash risk, as shown in a study, Crash risk factors for interstate large trucks in North Carolina, my colleagues and I completed several years ago and is still relevant today.
For this study, we partnered with the University of North Carolina’s Highway Safety Research Center and with the North Carolina Highway Patrol. Additional data were obtained from a brief questionnaire form for truck drivers and from the Federal Motor Carrier Safety Administration, which regulates trucking companies engaged in interstate commerce.
This study identified factors that increase large trucks’ crash risk by assessing large trucks involved in crashes and comparing them to control trucks. Trucks involved in crashes were eligible to be in the study if:
- the crash involved a fatality or injury with medical transport,
- and 2) if a Commercial Vehicle Safety Alliance Level 1 post-crash inspection was conducted.
For each crash-involved truck in our sample, we selected a control truck of the same type at approximately the same location as the crash and about the same time of day and part of the week (weekend vs. weekday). Each control truck selected also was subjected to a Level 1 inspection. This is known as a matched case-control study design. To ensure consistency in vehicles and in the rules they are subject to, we restricted the sample to trucks with gross vehicle weight ratings over 26,000 pounds and operated by interstate trucking companies.
A key reason for accurate and comprehensive record-keeping is to hold drivers who operate these large vehicles accountable for bad driving behaviors. This type of study in which the goal is to identify factors that increase large trucks’ crash risk is different than a crash causation study. For example, consider a situation where a car passes a truck, enters its lane, and slows rapidly. Arguably, the car’s maneuver is the main causal factor, but the presence or absence of truck brake defects could be the difference between a crash and an avoidance maneuver. So, if we are able to compare trucks with brake defects and those without, then we may be able to identify this as a risk factor. Using this theory, we employed a more statistically efficient way to do this by comparing crash-involved trucks with a control sample to look for differences in brake defects and other types of violations.
A common theme of the study’s findings was that violating rules was associated with increased crash risk. For instance, having inspection violations for vehicle defects (e.g., out-of-adjustment brakes, defective tires, inoperable lights) tripled the risk of crashing. For vehicle defect violations severe enough to put the truck out of-service, crash risk more than quadrupled. These results align with a similar study we published in 1989.
We found it was not just the truck’s history that mattered; the record of the driver and the company mattered as well. Drivers with one or more moving violations per year, on average, had a 30% higher crash risk than drivers with fewer moving violations. Drivers with out-of-service logbook violations had 50% higher crash risk. Drivers working for companies with histories of violations and crashes also had elevated crash risk. For instance, drivers for companies in which at least 10% of their roadside inspections resulted in trucks being placed out-of-service had 31% higher crash risk, and those driving for companies with over 100 crashes per 1,000 power units in the past two years had 71% higher crash risk.
Research studies like this and the development of appropriate interventions are only possible with accurate and robust recordkeeping. Moreover, for these efforts to be successful, records must accurately represent driver and motor carrier behavior. Charges that are adjudicated in such a manner that do not allow the behaviors to be accurately reflected on the driver and motor carrier records preclude studies from accurately measuring the association between specific violations and crash risk. Holding CDL holders and motor carriers accountable for their dangerous behaviors is just one step, albeit a vital one, in preventing large truck crashes.
Recognizing that enforcement alone cannot prevent crashes and their tragic outcomes, the Department of Transportation has adopted the Safe System Approach to address and mitigate risks in our transportation system. Acknowledging that humans make mistakes, the Safe System Approach addresses this by building and reinforcing multiple layers of protection to both prevent crashes and minimizing harm when crashes occur. Beyond rules and enforcement, other aspects of a Safe System for trucking would include addressing speed with technologies such as speed limiters and intelligent speed assistance and by setting and enforcing reasonable speed limits, equipping large trucks with strong rear and side underride guards, equipping trucks with crash avoidance technology, equipping other vehicles with crash avoidance technology that appropriately detects trucks, and establishing policies at every level that prioritize safety. Holding CDL holders and motor carriers accountable for their dangerous behaviors is just one step in preventing large truck crashes.
None of these are new ideas, but they are essential if we are to address the more than 4,000 lives lost each year due to large truck crashes—and the more than 40,000 people killed in all motor vehicle crashes. Road safety is a shared responsibility, and to that end, IIHS recently put forward a vision called 30×30 to reduce traffic fatalities 30% by 2030.5 This goal is ambitious but achievable and would put us closer to the ultimate goal of eliminating traffic fatalities. It involves doing the things we know are effective and doing them broadly. No single organization can achieve 30×30 alone. Please join us in working toward this vision and help ensure that more people arrive safely at their destinations.
