Why Are Pedestrian Fatalities On The Rise?

Marc Green

In March, NPR (National Public Radio) aired an interview with Alissa Walker of Curbed about the recent increase in pedestrian fatalities. After remaining steady for a decade, the numbers suddenly bolted upward in the last few years and are now approaching 6000 US deaths a year. This is likely beyond normal variability, suggesting a genuine trend. Something must now be different. But what?

Ms. Walker, we learned, knew the answer: "I mean, speed is what kills." Apparently, Ms. Walker's is not an expert on roadway safety, so the basis for her opinion is the ability to quote ideological clichés. Of course, NPR was only doing what such media outlets always do - relying on a pet special interest group which shares their ideology.¹

Obtaining more nuanced, informed, and objective opinion from an actual authority seemingly never entered their minds. NPR might have learned something that they didn't want to hear. For example, they may have learned that research clearly demonstrates that pedestrian behavior is the major cause of pedestrian fatalities and that many studies find that vehicle speed is not a highly significant factor in pedestrian deaths. Organizations including Toronto Police Services and the National Highway Transportation Safety Administration (NHTSA) have concluded that speed plays a limited role in pedestrian fatalities.

Moreover, blaming speed doesn't explain the recent fatality increase. What is the evidence that drivers are suddenly traveling faster over the last few years? If anything, sub/urban vehicle speeds have likely decreased in recent years. Most cities have reduced speed limits and increased the number of STOP sign and traffic signals while making more use of devices such as speed bumps and traffic calming. These measures only add to the already decreased speed caused by the massive congestion. Commute times are skyrocketing in most urban centers.

Whatever is causing the pedestrian fatality increase, there is no evidence that it is speed. Then what is it? There probably is no simple, single answer but rather a combination of factors. For didactic purposes, I have categorized proposed factors as exposure, traffic density, demographics, technology and alcohol/drugs. Some factors are likely more important than others and a few are possible but not yet proven.

Exposure

1. Exposure: increased population: Exposure is one factor that must always be considered when interpreting accident data. How many people have been exposed to the hazard? Any factor increasing exposure is likely to increase the absolute number² of deaths and injuries, even if everything remains constant. The increased population alone should then be a factor in the increased pedestrian fatalities. If exposure and numbers vary together, then the problem is not "growing." However, the population has been increasing gradually for many years, including the period when fatality numbers remained constant. There must be more going on.

2. Exposure - more cars: The population size is not the only exposure factor. The number of cars and the number of miles driven have probably grown at a faster rate than the population. The booming economy over the last ten years has likely increased the number of cars, especially for younger drivers (See below). Lower gas prices and longer commutes also likely increase the average car's amount of travel.

Traffic Density

3. Traffic density - attention effects: In addition to simple exposure effects, the increase in traffic places greater demands on road users. Gaining situational awareness becomes more difficult as drivers and pedestrians are forced to constantly switch attention from one location to another. For drivers, they will always prioritize attention to other vehicles over attention to pedestrians. The reality is that other vehicles are larger, more massive, and produce a much greater hazard, so drivers will always be primarily concerned with avoiding them. Further, the presence of other vehicles also increasingly blocks driver sightline making pedestrian detection more difficult.

To make matters worse, drivers now also have to worry about bicyclists. Drivers have only so much attentional capacity, so splitting it further toward bicycles leaves less for pedestrians. Think about the mental demand that the modern roadway creates. Drivers are now expected search for other vehicles, motorcycles, bicyclists, pedestrians, signs, signals and possible physical obstructions in the increasingly congested and cluttered roadway, all the while having to look around SUVs and keeping their vehicles in the proper lane. One consequence of the increased attentional load is greater reliance on schemata and expectations. Pedestrians and bicyclists who violate this expectations are then at greater risk. Pedestrians also have to search more and face a tougher task in locating vehicles. However, this is only a problem when they cross at midlock and other illegal locations. Moreover, the possible locations of approaching vehicles is limited.

4. Traffic density - risk acceptance effects: The increased traffic density results in fewer and smaller traffic gaps. Research has shown that both drivers and pedestrians then accept smaller gaps in order to avoid long waiting times. This could translate to more collisions as road users increase their risk tolerance and act with a smaller margin-for-error and more disregard for traffic rules. For example, drivers may become frustrated, pull out with incomplete search and run red lights while pedestrians also run red lights, dart out and run into the roadway, often using rolling gaps that leave them exposed.

Demographics

5. More younger drivers: Not only are there more cars, there are more young drivers. My high school had 3000 students, but only two had their own cars. The high school currently down the street from me has a large parking lot specifically for the students to park their cars, even though I live right in the city. In college, very few classmates owned cars. Students and the young once seldom owned a vehicle. The increased in wealth over the last half decade, however, has produced three and four car families with children having their own vehicles. The result is not just more cars on the road, but more cars driven by younger, inexperienced motorists. It could be speculated that this contributes to increased accident frequency because they are the population most likely to have a collision. There are also more older drivers, but contrary to popular opinion, evidence suggesting that they pose more risk is weak. They are more experienced, driver slower, accept only large gaps and do not drive much less at night and in poor weather.

6. Older pedestrians: Older pedestrians are frailer and are more likely to suffer serious injury or death in a collision. The increase in the older population would naturally then increase then the number of pedestrian fatalities. Because of slower walking speeds, older pedestrians are especially at risk on wider roads that take longer to cross, so the widening of roads to accommodate the increased traffic may also be having some effect. Further, there is the increasing phenomenon of bicyclists killing older pedestrians. This is a relatively rare event now, but it may not be in the future.

Technology

7. Smartphone distraction: Cell phone usage has increased greatly over the last two decades, yet pedestrian fatalities remained constant until the last few years. This uptick in fatalities correlates with the growing adoption of smartphones and not cell phone use in general. The explanation is obvious: smartphones encourage users to look away from the road and engage the far more cognitive and visual demanding tasks of texting and emailing. The accident data are just beginning to roll in, but they are showing that use of smartphones by pedestrians and by drivers is likely an important factor in the blossoming fatality number. Lastly, "infotainment" systems in cars are becoming more complex with more complex controls. These may well also add to drivers looking away from the roadway.

8. SUVs: Another technological factor is the advent of the SUV.³ It is likely a major factor responsible for the increase in pedestrian serious injuries and deaths. Studies typically find that a vehicle-pedestrian crash is more likely to result in a fatality when the vehicle is a "light truck" (LTV), the category that includes SUV's, than when the vehicle is a passenger car. Studies vary, with the effect ranging from 50 percent (Desapriya, Subzwari, Sasges, Basic, Alidina, Turcotte, & Pike, 2010) to 340 percent (Roudsari, Mock, Kaufman, Grossman, Henary, & Crandall, 2004) when adjusted for impact speed. They are especially deadly for older pedestrians (Lefler & Gabler, 2004). However, SUV drivers travel at higher speeds than sedans (Rudin-Brown, 2004) so their risk is even greater. The number of SUV's involved in fatal pedestrian collisions rose 82 percent from 2009 to 2016 (Hu & Cicchino, 2018). One study (Tyndall, 2021) reckons that replacing SUVs with sedans would have resulted 1,100 fewer pedestrian fatalities between 2000 and 2018. (Of course the assumptions required to make such estimates are usually iffy and biased to inflate the number.)

The SUV increases pedestrian fatalities several ways. These larger vehicles have high bumpers and flat fronts, so the point of contact with pedestrians is higher up on the body and not just with the legs. The collisions also cause pedestrians to bounce off with more violent contact with the ground (Simms & Wood, 2006). SUVs also have high horsepower and mass. Since an SUV ban is not happening any time soon, the only option is to redesign their fronts to cause less injury on impact. Recent research (IIHS, 2022) found that SUVs are much more like to fatally injure pedestrians during turns, suggesting sightline problems.

SUVs produce other safety hazards. They likely cause many collisions indirectly by blocking the view of following drivers, who cannot anticipate pedestrians or other hazards such as stopped vehicles ahead. They also block sightlines at intersections. Further, SUVs have also created an arms race on the road toward increased vehicle size. No sensible person wants to be driving a compact car when he collides with an SUV or light truck. Ironically, the Insurance Institute for Highway Safety has recommended that parents buy teenagers the biggest possible vehicles, like SUVs. They think it a good idea to have the worst drivers controlling the most massive and most dangerous vehicles.

9. LED and HID headlamps. Since most pedestrian fatalities occur at night, visibility (and alcohol) factors are a good place to look for causation⁴. What has changed recently in roadway lighting? The answer is headlamp technology. The increase in pedestrian fatality numbers correlates with the growth of vehicles fitted with LED and HID headlamps. Ironically, these new headlamps should theoretically allow better pedestrian detection because of their shorter wavelength spectrum and greater efficiency. However, these factors also promote massive glare for oncoming drivers as well as for pedestrians. Headlamps are designed to aim down, but common circumstances, e.g., a heavy object in the vehicle rear, a road incline, etc., cause them to aim upward and shine directly into the eyes of oncoming drivers. Further, SUV headlamps are mounted higher than those on cars, so they also cause more glare. The problem is exacerbated by growth in the older population, who experience higher levels of glare disability.

10. Risk compensation. When humans feel that some factor such as technology has made a situation safer, they tend to partially offset the safety gain by engaging in more extreme behavior. Drivers may believe that the brighter LED/HID headlamps, along the greater size of their SUVs, makes driving safer, at least for themselves. This could result in riskier driving.

Alcohol/Drugs

11. Alcohol: It is nothing short of scandalous that the media and public officials promote hysteria about drunken drivers but have remained virtually silent on the role of pedestrian drunkenness in road fatalities. NHTSA finds that 35 percent of pedestrians who are killed on the roadway had a BAC at or above .08. Removing child and elderly pedestrians, who are very seldom drunk, the percentage rises to nearly 50 percent in nonsenior adults. In fatal pedestrian crashes where one party was intoxicated, it is 3-8 times more likely that the alcohol was in the pedestrian than in the driver. Moreover, there is a clear upward trend, with the number of drunken pedestrian deaths at 1,944 in 2016, compared to 1779 in 2015 and 1600 in 2014 (NHTSA). That is 21.5 percent increase in only two years and represents about a third of the total pedestrian fatality increase during that period. Interestingly, the data show that although the number of drunken pedestrian fatalities has increased significantly, the rate has remained constant. In fact, it has remained constant going back several decades. Yet this has escaped public notice because safety authorities, doubtless for ideological reasons, continue to blame drivers for everything that goes wrong on the roadway.

12. Marijuana: States that have legalized marijuana usage report a 16.4 percent increase in pedestrian fatalities between the first half of 2016 and 2017 compared a collective 5.8 percent increase in states that have not (according to the GHSA). It unclear whether the major factor is a drug in the drivers or in the pedestrians and whether marijuana was the cause in all or some of the crashes - remember that correlation is not causation. Taken at face value, however, this bodes ill for the future as many more states (and all of Canada) are soon legalizing marijuana.

Conclusion

Most of these factors have been gradually increasing over many years, including the period when pedestrian fatality numbers remained relatively constant. While they may account for some of the fatality increase, it is best explained by factors that have changed the most over the last 5-6 years. By this criterion, the obvious culprits lie in technology, smartphones, LED/HID headlamps, infotainment systems and SUVs. Of course, it is always possible that some longer term trends have reached a critical value or tipping point (see "catastrophe theory") or may also have been initially offset by factors such as the 2008 economic crash and by technology such as ABS brakes and hands free phones.

The more important questions are "Where do we go from here?" and "What to do?" Most of the major negative trends, population growth, number of cars, aging population, number of SUVs, growing traffic density, increasing smartphone distraction, etc. are only likely to make the situation worse while others which are currently minor, such as marijuana and bicycle collisions with pedestrians, are likely to become significant.

Solutions are problematic. Maybe we can hope that cars with pedestrian detection technology will bail us out. Possible, but that's still in the future, even if it works. Instead, it is better to look at the factors that cause collisions to occur and see what can be done. Lower speeds aren't the answer because speed is not a major factor. The major factor is pedestrian behavior. The vast majority of fatalities occur when pedestrians are crossing illegally, darting into the roadway, drink walking, distracted by smartphones, wearing low visibility clothing and so on. These are all behavioral choices, but as I describe elsewhere, they are not viewed by pedestrians as risky behavior. Forcing pedestrians to behave more safely through contingencies is the obvious step. This can only be accomplished by enforcing current traffic laws for illegal crossing and by penalizing smartphone distraction in both pedestrians and also in drivers in proportion to the risk that they create. Drivers currently only receive a slap on the wrist. Texting while driving should receive a draconian penalty, such as immediate license loss. Yes, it is that dangerous. Constraining infotainment systems would also be wise. However, there seems no political will to take such steps and even less to address other major problems such as pedestrian drunkenness, or the growth of LED/HID headlamps and SUVs. There is even less will to address population growth, which directly and indirectly has caused this and many, if not most, of society's other major problems. In sum, don't expect pedestrian fatality numbers to decrease anytime soon.

Endnotes

¹See, for example, journalist Bernard Goldberg's book, Bias: A CBS Insider Exposes How the Media Distort the News.

²Though not necessarily the rate, which is the number divided by exposure. Numbers can easily rise (or decline) with the rate unchanged.

³SUVs are often confused with crossovers. An SUV is a sports utility vehicle built on a truck frame. A crossover is a sports utility vehicle built on a car frame. However, the distinction is seldom made in everyday speech.

⁴The ratio of pedestrian fatalities at night vs. day is 3:1. However, there are fewer pedestrians walking at night. When the exposure difference is taken into account, pedestrian fatality risk is seven times greater at night.

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