New data bombards us, regardless of what we do. Given what I do for a living, I see a constant stream of truck accident data and studies. While I read, digest, and comment on this data, federal regulators make new laws based on the same studies, and responsible trucking companies use them to devise new safety procedures for their drivers.
One thing that very few of us ever do is look back at old studies to gauge whether researchers viewed the issues of their day through the right end of the telescope. Recently, I came across a study titled, Car/Truck Accidents in Texas 1976-1979. Looking through this study is a fascinating read, because of what the authors, while well-meaning, got spectacularly wrong. Looking back 40 years later, it's amazing how many of the authors' concerns would be irrelevant in just a few short years.
A Quick Look at the Trucking Accident Landscape in the late 1970s
Comparing truck accident deaths through the years, it might be easy to conclude that not much changed. For instance, 4,305 people died in large truck accidents in 1975, while 4,119 people lost their lives in such crashes in 2019. Looking at both numbers, it's easy (and absolutely wrong) to conclude that things are pretty much as they were in 1975. Dig a little deeper and you'll find that the chance of dying in a commercial truck accident was 491% higher in 1975 than in 2019. So how did truck accident deaths decline nearly five-fold in a little over 40 years?
Commercial Truck Accidents Surged in the Late-1970s
In fairness to the authors of the study, it's important to understand the time they studied. Between 1975 and 1979, commercial truck accident deaths surged 51.9%. A large portion of the increase occurred because commercial trucks traveled 34% more miles in 1979 than they did in 1975. It's likely that much of the rest of the increase came from the last of the baby boomers becoming old enough to drive and an influx of new drivers into the trucking profession. Since inexperienced drivers of all types are most likely to cause fatal accidents, 1975-1979 represented a peak for inexperienced drivers on the roadways.
Of course, the 1970s also saw oil embargoes from Middle Eastern countries, which changes how Americans looked at gasoline. The ensuing shortages resulted in a demand for increased vehicle fuel economy. The easiest way to achieve this in the short run was to make cars lighter. The study authors note this trend. They also point out that the same fuel scarcity led to increases in vehicle weight for commercial trucks. It made sense from a fuel economy standpoint to haul as much cargo as possible on each trip that a truck took.
Emissions Concerns Affected Car Performance
While the study authors discuss vehicle size at great length, they don't call attention to other impactful trends from the 1970s. A newfound focus on emissions and vehicle pollution triggered impactful changes. A government-mandated switch from leaded to unleaded gas robbed many vehicles of performance. Adding pollution controls, such as catalytic converters further choked the engines of the time. The study authors mention poor acceleration as a potential source of some crashes, but they fail to understand why vehicle performance was poor in the first place. While they don't come out and say it, their analysis equates acceleration with engine size. This mistake neglects the fact that even cars with large engines accelerated poorly in the 1970s.
With that background, it's easier to understand how this study's predictions ended up getting so much wrong. The authors do a thorough job of understanding the effects of vehicle size and the increase in highway fatalities but failed to understand the evolving technological and legal landscapes, which ended up making many of their concerns misguided in retrospect.
1990: The Year of Tiny Cars and Giant Trucks
Nowhere did the authors' speculation miss the mark more than when they asserted that by 1990, fewer than 2% of American cars would be large cars, while the majority would drive compact and sub-compact cars. Obviously, this did not come to pass.
Again, I'm not picking on the researchers. Had the car industry not changed in the 1980s, had the gas shortage not turned into a gas glut, and had consumer behavior continued responding to 1970s market conditions through the 1980s, then their prediction likely would have hit closer to the mark.
This wasn't the only side of the equation that the researchers missed. They noted that trucking companies responded to increasing fuel prices by increasing the loads on trucks, thereby increasing commercial truck weight. As a result, the amount of energy that trucks carried into crashes increased, resulting in more fatalities.
Researchers couldn't predict the rise in package delivery services such as UPS and FedEx. These 2 companies account for the lion's share of commercial trucks on the road today. Their average truck is significantly smaller than a fully-loaded tractor-trailer combination. So while passenger cars didn't decrease in size as much as predicted, the commercial truck weight didn't increase as much as anticipated, either.
The Researchers Missed How Quickly the World Would Change
Sports-Utility Vehicles, Mini-vans, lower fuel prices, more efficient engines, safer vehicle designs, mandatory seatbelt laws, increased drunk driving enforcement, and airbags were just some of the innovations that hit affected vehicle travel in the 1980s.
Each of these innovations contributed to a fleet that differed greatly in the 80s from what researchers predicted at the end of the 1970s. Had things not changed, then commercial truck accidents likely would have continued to increase throughout the 1980s. However, they did, and by 1990, a person was 232% less likely to be involved in a fatal commercial truck accident than they were in 1980.
If the researchers were guilty of any mistake, it was projecting a short-term trend from the late 1970s far into the future. The problem with an "if these trends continue" mindset is that very few trends continue indefinitely because the world always changes.
What Can Be Learned from the Mistake in Old Studies?
At this point, you may be wondering, "So what, Jeff? A couple of researchers made some bad predictions 40 years ago. What's the big deal?" It's a fair criticism, and my response is that as a society, we rely on a constant barrage of studies to inform our view of the world and what should be done to improve it.
Deep down, we know that the shocking study of the day is not perfect, but rarely does anyone go back and review these studies years later to see where they were correct and where they went off the rails. This is a missed opportunity because the same mistakes often crop up again and again.
Behavior Often Trumps Material Factors
Just take seatbelt laws as one example. Mandatory seatbelt usage didn't exist at the time the researchers conducted their study. In a world where now close to 90% of all people in a vehicle wear a seatbelt, it's easy to understate how much of an impact this simple behavior has when it comes to increasing the survivability of a crash. Even in smaller cars, people today survive at much higher rates when they're not ejected from the vehicle. But what is obvious today, was a novel idea in the late-1970s.
While it's certainly interesting to speculate about the impact of smaller vehicle size, it obscures that behavioral changes can do more than any change in material conditions. Even today, a staggering proportion of vehicle accident fatalities occur among the 10% of the population that doesn't wear seatbelts.
Behavior In Complex Systems Is Difficult to Predict
It's not that researchers in this study didn't try to predict behavior, they just focused on the wrong behaviors. Predicting an increased preference for compact and sub-compact cars is a behavioral prediction. The problem is that road safety has so many players, with so many different interests and behaviors.
To predict the changes that took place just a few years after the report came out, researchers would have needed to know how lawmakers, regulators, the car industry, the trucking industry, and the average driver would behave over the next 10 years. Obviously, the complexity of that problem is infinite. This is likely why so many alarming trends don't continue on a predictable path. Awareness and changes in behavior invariably alter the trend line.
Certainly, had automakers not developed more powerful, efficient, and safer cars, consumers may have continued to downsize. Had legislators not cracked down on drunk driving and mandated seatbelts, deaths would likely have continued their upward trajectory.
The Takeaway: Be Vigilant When Someone Simple Explanations to Complex Systems
If I am perfectly frank, this is one of the better road safety studies I have come across. It presents a lot of quality data about where crashes occurred, how many people died, and provided a useful starting point for discussing road safety on Texas roads in the late 1970s.
The only mistakes came when the researchers ventured away from gathering data and into making conclusions. This problem afflicts many of the studies we see today. Even when good researchers properly measure a problem, like truck accident fatalities, the complexity of all the events that lead to a commercial vehicle accident means that suggestions for improvement will miss key factors in such crashes.
This applies to studies in pretty much every area of life. The researchers in this old study don't have an obvious ideological ax to grind but still managed to focus on contributing factors that technology rendered largely irrelevant within a few years of the report's publication. Given that not every researcher is so constrained by the facts, it makes vigilant reading even more important for the public and policymakers.