Single-vehicle, single-pedestrian crash data for 2016-2021 finds hoods a problem.
It’s hard to escape the fact that American trucks and SUVs have been on a steroid-infused diet for the last few years. The trend was all too apparent at the last auto show we went to—at Chicago in 2020, I felt physically threatened just standing next to some of the products on display by GMC and its competitors. Intuitively, the supersized hood heights on these pickups seem more dangerous to vulnerable road users, but now there’s hard data to support that.
It hasn’t been a great few years to be a pedestrian in the United States. These most vulnerable road users started being killed by drivers more frequently in 2020, and while some states were able to reverse that trend, others went the other way, making 2022—the last year for which there is full data—the most deadly year on record for US pedestrians.
The problem has multiple causes. For decades, urban planners have prioritized car traffic above everything else, and our built environment favors speeding vehicles at the cost of people trying to cross roads or cycle. But it’s not all just the fault of those planners, as the vehicles we drive play a large role, too.
Some of that is the switch from sedans to crossovers, SUVs, and pickup trucks. Data from the 1990s found that a pedestrian hit by a light truck was two to three times more likely to be killed, with another study finding that light trucks were twice as likely to injure a pedestrian than a car, especially at low speed.
Now, a new study published in the journal Economics of Transportation has analyzed the National Highway Traffic Safety Administration’s crash data from 2016–2021, looking at crashes involving one vehicle and one pedestrian. The author, Justin Tyndall at the University of Hawai’i, matched NHTSA’s crash reporting sampling system data for those years to vehicle specifications where the vehicle’s VIN was included in the CRSS data.Advertisement
Tyndall’s data set started with 13,783 single-vehicle, single-pedestrian crashes, then filtered out those instances where there was no VIN recorded, except if the report included make and model. He also removed entries that did not record other important variables, such as vehicle speed, leaving a sample size of 3,375 crashes.
To make sure the smaller data set was still representative, Tyndall looked at the full data set as well as the final sample. He found “that average crash characteristics are similar across the two samples, suggesting that the reduced sample is broadly representative of the original data set,” although he notes that 6.7 percent of crashes in the large set resulted in a pedestrian death, while 9.1 percent of crashes in the smaller, final sample were fatal for the pedestrian.
Pickups and SUVs are more dangerous to pedestrians
There were 1,779 unique vehicles (as determined by make, model, and model year) in the data set. Pickups and full-size SUVs had significantly taller hoods than the average car, at 28 percent and 27 percent, respectively. Minivans weren’t much better, at 24 percent taller than the hood on an average sedan. Even compact SUVs—also known as crossovers—were 19 percent taller. Pickups and full-size SUVs were also much heavier than the average vehicle: 55 percent for SUVs and 51 percent for pickup trucks.
Tyndall also notes that while the data set only spans six years, over that time, “the median front-end height increased by 5 percent,” while weight increased slightly less (3 percent), and the chance that the vehicle was a light truck rather than a car went up by 11 percent.
Of the 3,375 crashes, 308 saw the vehicle kill the pedestrian. When examined by vehicle type, vans proved to be the least dangerous to pedestrians, with a 6.6 percent chance of death. Cars were a bit worse—8.5 percent of pedestrians hit by a sedan or hatchback were killed. Compact SUVs were roughly the same as cars at 8.8 percent.
But full-size SUVs and pickup trucks were significantly more deadly to pedestrians. Of pedestrians hit by pickup trucks, 11.9 percent were killed in the crash, rising to 12.4 percent for pedestrians struck by full-size SUVs.
It’s clear from the data that hood height plays a significant role in this death toll, together with vehicle weight. Tyndall finds that the chances of a pedestrian dying in a single-vehicle crash were 68 percent higher when that vehicle was a light truck relative to a car, all else being equal.
Looking at more granular data, he also finds that compact SUVs increase the probability of death by 63 percent relative to a car, pickup trucks increase the probability by 68 percent relative to a car, and full-size SUVs increase the probability by 99 percent. (Vans were overrepresented in minor crashes, and the increased probability of a pedestrian dying when hit by a van was not significant.)
It’s mostly how tall the hood is
When Tyndall controlled the data for vehicle body type, the effect of vehicle hood heights became more clear, actually increasing “the partial effect of front-end vehicle height, suggesting high-front-end designs are specifically culpable for higher pedestrian death rates, and this is not driven by other characteristics that are correlated with front-end height,” he writes. In fact, the study estimates that a 4-inch (100-mm) increase in front end height translates to a 28 percent increase in pedestrian death.Advertisement
Other variables were also associated with worse outcomes. Pedestrians struck at night were three times more likely to die than if they were hit by a vehicle during daylight. The gender of the driver did not matter, but under similar crash circumstances, women pedestrians were killed at a rate 70 percent higher than men, although Tyndall notes that the “difference between the raw data and the regression result suggests that women are involved in very different types of crashes. For example, the average vehicle speed for crashes with a female pedestrian is lower.” Age is a factor, too, with older pedestrians being more vulnerable to vehicles with high hood heights.
In a thought experiment, Tyndall calculated what would happen if vehicle hood heights were limited by regulation to 49.2 inches (1.25 m) or less. “Across the 2,126 pedestrians killed by high-front-ended vehicles (1.25 m), I estimate 509 lives would be saved annually by adopting a 1.25-m front-end limit. The lives saved equal 7% of annual pedestrian deaths. Reducing the limit to 1.2 m would spare an estimated 757 pedestrian lives per year, and further reducing the cap to 1.1 m would spare an estimated 1,350 pedestrian lives per year,” he writes.
Currently, it seems unlikely that NHTSA will move to regulate hood heights on new vehicles. In the meantime, let’s hope designers and executives at the various automakers that build these vehicles read this research.
Economics of Transportation, 2024. DOI: 10.1016/j.ecotra.2024.100342 (About DOIs).
