Understanding the Problem
Roadway environment, vehicle type and design, weather, and road user behaviors contribute to pedestrian crashes. These factors are not mutually exclusive, and risky behaviors such as speeding, impairment, and distraction introduce a compounding effect. Reducing risky driver behaviors improves safety for people walking. While reductions in crashes and injuries are the gold-standard for evaluating countermeasure effectiveness, it is important to note that the absence of crashes does not necessarily indicate the presence of safety. People may be dissuaded from walking along certain routes because of perceived threats to safety even in areas without high crash numbers.
Traditional safety management methods attempt to address safety through infrastructure improvements at high-crash locations, but they may be unable to reduce the network-wide risks. The Safe System approach has been adopted by cities, States, and the U.S. DOT to eliminate fatalities on the roadway (U.S. DOT, 2022). The National Roadway Safety Strategy recognizes that no mistake made by a road user should lead to death and seeks to build a transportation system that prevents serious and fatal crashes for all road users. The Safe System approach is a way to look beyond reducing raw crash numbers toward reducing (and eventually eliminating) the forces and risks in our transportation system that create death and serious injury. This concept is especially important for pedestrian safety because modern vehicle technology protects occupants from much of this energy impact, but people outside the vehicle remain particularly susceptible (Kumfer et al., 2019).
Pedestrians are particularly vulnerable to severe injury and fatality in crashes; countermeasures aimed at reducing speeds have the potential to save lives for both pedestrians and drivers. The risk of death or serious injury increases along an S-shaped curve as the impact speed—which is a product of speed limits, the built environment’s cues to drivers, and driver behavior—increases. The study by Rosen and Sander (2009) estimated the risk of pedestrian fatality based on driver impact speeds using data from a sample of more than 2,000 pedestrian fatalities. The study estimated fatality risk curves based on driver impact speeds, ranging from 8% at 31 mph and reaching 50% at 47 mph. Other studies have estimated similar relationships, although the magnitude varies (Leaf & Preusser, 1999; Tefft, 2011). The figure below shows the adjusted, standardized risk of severe injury and the risk of death for pedestrians by impact speed from a sample of 422 pedestrians 15+ years struck by a single forward-moving car or light truck model year 1989–1999, United States, 1994–1998. Risks are adjusted for pedestrian age, height, weight, body mass index, and type of striking vehicle, and standardized to the distribution of pedestrian age and type of striking vehicle for pedestrians struck in the United States in years 2007–2009. Dotted lines represent pointwise 95% confidence intervals. Serious injury is defined as AIS score of 4 or greater and includes death irrespective of AIS score (Tefft, 2011).
Risk of Severe Injury (Left) and Death (Right) in Relation to Impact Speed
Source: Tefft (2011)
Tefft (2011) also includes graphics showing risk in relation to speed for older adults and by type of striking vehicle. Since travel speed data are challenging to obtain, researchers often use speed limit data as an imperfect surrogate. In their guide on systemic pedestrian safety analysis, Thomas et al. (2018) consider speeds greater than 25 mph as risk factors in areas of pedestrian activity. Driving speed also appears to affect the tendency for drivers to yield to pedestrians at crosswalks, with fewer drivers yielding as speeds increase (Bertulis & Dulaski, 2014; Gårder, 2004; Sandt, Gallagher & Gelinne, 2016). See Speeding and Speed Management for speed-related countermeasures. For a comprehensive synthesis on speed management and countermeasures that may reduce speed, see NCHRP Synthesis: Pedestrian Safety Relative to Traffic-Speed Management (Sanders et al., 2019).
The role of alcohol in pedestrian crashes has not been well defined, based on the lack of complete and high-quality data on alcohol use or BACs of drivers and pedestrians involved in crashes. A BAC of .08 g/dL is commonly used to indicate impairment in a road user regardless of mode. While this measure relates to the ability to operate a vehicle, research has not established whether this is a meaningful threshold for walking. In 2021 some 43% of all crashes resulting in pedestrian fatalities involved either a driver or pedestrian with a BAC of .08 or higher (NCSA, 2023c). Thirty-one percent of pedestrians killed in crashes had BACs of .08 or higher, while 19% of fatal pedestrian crashes involved drivers with BACs of .08 or higher. From 1982 to 2014 the proportion of fatally injured pedestrians with BACs of .08 or higher decreased at a lesser rate than fatally injured passenger drivers with BACs of .08 or higher (Eichelberger et al., 2018). While crash statistics measure the BACs of road users, other studies attempt to link alcohol use with pedestrian safety in particular. A study that combined crash data and driving record data from 5 States found that people with prior alcohol-related driving offenses may be at greater risk for being killed as a pedestrian with a BAC over .08 compared to those without prior driving offenses (Blomberg et al., 2019). While studies involving roadside data collection have assessed the prevalence of drinking and drugged driving, less in known about the prevalence among people walking or bicycling. A convenience sample of seriously and fatally injured road users suggests drug and alcohol prevalence is similarly high regardless of mode (Thomas et al., 2020). Alcohol use is also related to the land uses that permit alcohol sales surrounding a road. A study of alcohol outlet density and pedestrian safety in Baltimore City found that each additional off-premises alcohol outlet was associated with a 12.3% increase in the risk of pedestrian injuries in the neighborhood, and an attributable risk of 4.9% (Nesoff et al., 2018). Alcohol-related countermeasures that may also help address certain pedestrian crashes are presented in the Chapter on Alcohol-Impaired Driving.
Alongside factors such as speed and pedestrian age, the design of the vehicle contributes to the injury severity for the person outside the vehicle as well as the occupants. Eighty-five percent of all pedestrian injuries are caused by impact with the vehicle, even if the pedestrian strikes the pavement (Hu & Klinich, 2012). Vehicle weight, size, and power have been found in several studies to increase the risk of fatality and injury when a pedestrian is struck (Thomas et al., 2018). Although involvement of all types of passenger vehicles and medium or heavy trucks in pedestrian fatalities increased from 2009 to 2016, the rate of increase was highest among SUV-class vehicles (81%) compared to minivans and large vans (15%), and passenger cars (41%) (Hu & Cicchino, 2018). During this time, the number of registered SUVs increased 37%. In addition, the power-to-weight ratio increased significantly among all weight classes of passenger vehicles, and pedestrian fatality involvement of pickups, and medium or heavy trucks, each increased by 32%. Anywhere from double to triple the risk of fatality for the pedestrian has been correlated to crashes with light trucks when compared to crashes with passenger vehicles (Hu & Klinich, 2012). From 2016 to 2018 about 6.6% of all pedestrian fatalities involved a large truck (defined in FARS as a truck with a gross vehicle weight rating greater than 10,000 pounds) (FMCSA, 2020). While most people walking or bicycling who are fatally struck by a motorist are initially struck by the front of the vehicle, large trucks make up the highest percentage of right-side impact and rear impacts in pedestrian fatalities (NCSA, 2023c).
Distraction is considered anything that diverts a traveler’s attention from the primary task of navigating the roadway environment and responding to critical events. In the case of pedestrian distraction, the conversation has focused on distraction via smartphones. A literature review from NHTSA found that, based on the limited amount of research done on pedestrian distraction, distraction is associated with a small but statistically significant decrease in pedestrian safety (Scopatz & Zhou, 2016). Talking on cell phones is associated with cognitive distraction that may reduce the frequency of prudent pedestrian behaviors (Hatfield & Murphy, 2007; Nasar et al., 2008; Ortiz et al., 2017; Stavrinos et al., 2009, 2011); however, the results from real-world observational studies are mixed (Walker et al., 2012; Thompson et al., 2013). A study of road user distraction at four intersections in Washington, DC, found that of the 4,871 people observed, the primary form of distraction was engaging with other people for both pedestrians (44%) and drivers (49%) (Ortiz et al., 2017). More than a quarter (27%) of all people observed were distracted by cell phone use. The prevalence of distraction among pedestrians was higher than for drivers: pedestrians had 1.5 increased odds of being distracted. Thompson et al. (2013) sampled pedestrian behaviors at 20 high risk intersections and reported that only pedestrians who were texting were associated with suboptimal crossing behaviors. Most interactions (20 of 21) between distracted pedestrians and distracted drivers resulted in some form of evasive maneuver by either (Ortiz et al., 2017).
The studies described above report 7% to 30% of pedestrians using varying types of portable electronic devices and confirm that device use effects pedestrian crossing behavior, but they do not establish direct links between pedestrian distraction and pedestrian-involved crashes. Looking specifically at smartphone use, a review of observational studies of distracted walking found rates ranging from 1.1% to 8.4% of observed pedestrians (Gary et al., 2018). The review also separately considered survey-based studies, which tended to find higher rates of smartphone distraction. Nationally representative estimates on use of portable electronic devices are not available since distraction is not a universal variable on police crash reports, but would likely only capture a snapshot in time, as device use continues to grow in popularity. FARS/CRSS data on pedestrian device use or involvement in pedestrian crashes is not complete (NCSA, 2023b).
Engineering and Roadway Design
The countermeasures described in this guide relate primarily to educational and enforcement measures aimed at improving knowledge and preventing behaviors that contribute to crashes. Roadway design and engineering also impact road user behavior, both pedestrian and drivers, affecting safety for pedestrians. The Safe System Approach (U.S. DOT, 2022) recognizes the integrated role of different measures, including roadway design, in creating a safe, welcoming environment for all road users. The Safe System Approach recognizes the vulnerability of road users, especially for those unprotected by a vehicle and seeks to employ layers of protection that include safer roads to prevent serious and fatal crashes. The U.S. DOT’s (2014) national pedestrian safety action plan focuses significant attention on built environment research and countermeasures.