CHAPTER 4

Conclusions and Suggested Research

4.1 Commitment to Improving Pedestrian Safety in the U.S.

Walking (including using mobility devices like wheelchairs) is a fundamental human way to travel, yet is too often inaccessible, uncomfortable, or unsafe as a practical option for large numbers of people due to traffic risk, discomfort, or inconvenience – especially at night. This constrained and unsafe walking reality results from decades of auto-centric planning and engineering in the U.S. that has encouraged sprawl and prioritized motorist throughput and speed over pedestrian access and safety. Our research corroborated other studies and shed new light on the relationship between multilane roadways, higher design and posted speeds, and a lack of safe and convenient pedestrian walking and crossing facilities and operations – even at known attractors like bus stops and grocery stores – and pedestrian fatalities at night in the U.S. (Sanders, Schneider, and Proulx 2022; Ferenchak and Abadi 2021; Dumbaugh et al. 2023).

To reverse the tide of increasing pedestrian fatalities in the U.S. and create a safe system, our research identifies possible ways to address roadway design approaches and standards. Walking is an important part of the transportation system and a primary travel mode that provides access to all other modes of travel. Planning for safe walking will benefit all roadway users. To meet the challenge of substantially improving pedestrian safety at night, transportation practitioners can:

• Reduce the potential for a severe outcome through managing vehicle speeds,
• Decrease the likelihood of a crash through increasing driver awareness of pedestrians (enhancing visibility) and mitigating decades of driver-centered design, and
• Reduce pedestrian exposure (i.e., the time pedestrians spend in the roadway) to vehicles.

The companion document to this research, Strategies to Improve Pedestrian Safety at Night: A Guide, helps practitioners understand how to reduce pedestrian risk in darkness and create safe, convenient pedestrian infrastructure throughout our transportation system. To address pedestrian safety, especially for groups with higher documented risk, practitioners can focus on high-risk or high-exposure locations with the following elements:

• Proximity to commercial districts, convenience stores, grocery stores, liquor stores, transit stations/stops, entertainment districts and high-density residential areas (this research; Long and Ferenchak 2021),
• Higher posted speeds, especially on arterials (this research; Sanders, Schneider, and Proulx 2022),
• Multiple lanes, especially on arterials (this research; Sanders, Schneider, and Proulx 2022),
• Wider lane widths (Fitzpatrick and Park 2021), and
• Lack of sidewalks (Long and Ferenchak 2021).

In addition to an intentional focus on managing vehicle speed and mitigating auto-centric design, our research and companion guide discuss myriad actions that local and state transportation and planning agencies can take to create a holistic, systemic approach to improving pedestrian safety at night. These actions range from revising planning and engineering policies related to traffic forecasting, roadway design

• Evaluate proven and promising safety countermeasures in nighttime conditions and in a variety of circumstances to better understand their effectiveness. For example, Fitzpatrick and Park (2021) evaluated PHBs, RRFBs, and LED-embedded crossing signs during darkness versus daylight, but we found no other studies that focused on treatment effectiveness at night. Other types of pedestrian safety treatments that could be tested specifically at night versus daytime include marked crosswalks (including the visibility of different types of crosswalks at night), median islands, curb extensions, lane reconfigurations (i.e., road diets), and reduced speed limits. When are countermeasures sufficient on their own versus needing to be combined for the desired effect on driver behavior in darkness along arterials?
• Evaluate the nighttime pedestrian safety effects of more types of transportation facilities. In addition to analyzing the effectiveness of specific pedestrian safety treatments, researchers could evaluate pedestrian safety at night in relation to a wider variety of transportation facilities, including roundabouts, different types of driveway crossings, alleys, and parking lots.
• Test the effectiveness of lower nighttime speed limits. We found no research that examined the potential effectiveness of lower nighttime speed limits for pedestrian safety. This type of treatment is currently rare in the United States, and it has only been evaluated recently for rural highways. Good initial candidate locations for testing nighttime speed limits would be corridors with high numbers of nighttime pedestrian crashes.
• Examine the nighttime pedestrian safety effects of LED streetlights. Many communities have transitioned their streetlights to LED technology, and it is important to quantify the effect of LED lights on pedestrian crashes, injuries, and fatalities.
• Investigate the potential unintended consequences of nighttime pedestrian safety treatments in locations and on pedestrians who do not have the protection of the treatment. We did not find any studies that examined drivers’ abilities to detect and react to pedestrians in typical conditions after they had experienced a high-visibility treatment. For example, RRFBs could emphasize the presence of pedestrians at a specific crosswalk, or a retroreflective vest could increase the visibility of a pedestrian. However, the principle of driver expectancy (Tijerina 2016) suggests that drivers who have seen the high-visibility treatment enough times might become used to it and then be less likely to look for and be prepared to react to pedestrians in normal conditions (e.g., at a crosswalk without a RRFB treatment or pedestrians in normal clothing). Could these safety treatments potentially increase risk during darkness for locations or people without high-visibility treatments? If so, what are strategies to mitigate that increased risk?
• Examine the impact of an all-road-user transportation operations approach (NCHRP Research Report 1036, Semler et al. 2023) to both intersection operations and traffic safety outcomes across modes. Our traditionally vehicle-focused methods too often result in overdesigned roadways planned for capacity that may never materialize or is decades away. How does an all-user approach change shorter- and longer-term safety and operations outcomes, and what are the consequences of those changes for communities?
• Investigate possible changes to roadway design standards in response to the larger, taller, boxier, and heavier vehicles that comprise most new vehicle sales. Metrics such as braking distance, deceleration and acceleration time, the driver’s eye height, and sight distance could be tested using these newer vehicles to determine if and how those values could be adjusted.

Possible Safe Vehicles Research Topics

• Analyze the effect of vehicle cabin light sources on pedestrian risk at night. Types of cabin light sources include entertainment systems, driver assistance displays, portable electronic devices, and ambient cabin lighting designed to enhance in-vehicle atmosphere. We identified one study that explored the impact of interior cabin lighting on drivers’ abilities to detect pedestrians (Devonshire and Flannagan 2008). It found evidence that interior lighting decreased driver detection distances and

• speculated that the problem may be even worse in practice than it was in the experimental environment tested. Since new interior lighting features continue to be developed, the impact of this lighting on pedestrian risk could be evaluated as a part of new vehicle safety standards.
• Quantify the distance drivers can detect pedestrians with their vehicle headlights at night more precisely. We found many studies that tested driver detection of pedestrians at different distances during darkness, but few provided a measure of how far away pedestrians could be detected by drivers in vehicles with common headlight designs. One study suggested this distance might be 80 meters (Bhagavathula, Gibbons, and Nussbaum 2020), but more information about the variation in this measurement across a variety of headlight designs, vehicle types, and driver characteristics would be helpful. This research can help inform headlight design and roadway design.
• Study how vehicle blind spots could potentially lead to higher pedestrian crash risk at night. There is little research on how vehicle shapes, frame configurations, and window designs affect the ability of drivers to see pedestrians and ultimately affect pedestrian crashes during darkness.
• Explore how sub-optimal conditions may limit the effectiveness of vehicle headlights and pedestrian lighting. Test vehicle headlights and pedestrian lighting in a variety of weather conditions (e.g., rain, snow). Gather information about how often streetlights are blocked by street trees or other overgrown landscaping. Try to understand how the sub-optimal lighting in these situations might affect drivers’ abilities to detect pedestrians and affect pedestrian crashes at night.

Possible Safe Road Users Research Topics

• Analyze the effect of mobile phone usage on pedestrian crash risk in the daytime versus at night. We hypothesize that pedestrian risk will be worse at night because drivers’ eyes need time to adjust between looking at a bright screen and dark roadway conditions. However, we did not find any studies that examined this issue directly.
• Determine how long it takes drivers’ eyes to adjust to different levels of lighting and different types of glare and contrast. We found evidence that lighting level, glare, and contrast are related to drivers’ ability to detect pedestrians, but we only found limited research showing how long it takes drivers’ eyes to adjust to changes in each of these environmental characteristics (Dewar 2016a). None of this research focused specifically on pedestrian detection. Additional research on this topic is particularly important where drivers transition from rural areas with lower lighting levels to urban areas with higher lighting levels (and similar transitions within urban and suburban areas), and vice versa.
• Evaluate driver drowsiness as a contributing factor to nighttime pedestrian crash risk. Driver fatigue is a risk factor in traffic crashes (Dingus et al. 2016). Studies could use in-vehicle camera recordings to evaluate how driver fatigue relates to detecting pedestrians at crossing locations. Other research could evaluate the pedestrian safety effectiveness of on-board driver monitoring technologies that help alert drivers when they become drowsy.
• Examine what pedestrians understand and perceive about traffic and traffic risk at night. How do pedestrians understand and evaluate their crossing and walking risk at night, and how do they adjust for such perceived risk, if at all? How does this understanding differ across pedestrians according to sociodemographic characteristics?
• Previous studies have identified higher pedestrian fatality risk for Black, Hispanic/Latino, Pacific Islander, and Native American communities, but have not comprehensively identified why. Additional research could help identify underlying causes.
• Study why pedestrian nighttime risk might be higher for pedestrians with disabilities and wheelchair users. Quantify the number of pedestrian injuries and fatalities at night that involve people with disabilities. Estimate the population-based risk of pedestrian injuries and fatalities at night for people with disabilities. Conduct more in-person, ethnographic, and investigative research to understand factors underlying pedestrian risk at night for people with disabilities and how these risks may differ for those who have cognitive or physical disabilities. Strategies employed to reduce

• pedestrian risk at night may need to be adjusted to provide the same protections to pedestrians with disabilities and wheelchair users.
• Understand pedestrian risk at night for the unhoused population. Quantify the number of pedestrian injuries and fatalities at night that actually involve people who are unhoused. Estimate the population-based risk of pedestrian injuries and fatalities at night for people who are unhoused. Conduct more in-person, ethnographic, and investigative research to understand factors underlying pedestrian risk at night for the unhoused population.

Possible Post-Crash Care Research Topics

• Explore how improvements in emergency medical system response and emergency room treatment practices have affected pedestrian survivability at night. Gather this information to disentangle the effect of increased time to treatment from overall crash severity for pedestrians involved in hit-and-run crashes. This could include investigating response times in different land use contexts, such as urban versus rural. Further, do staffing differences, employee fatigue, and other challenges in the health system labor market affect medical outcomes broadly at night in emergency medicine?
• Collect post-crash information from drivers and pedestrians involved in crashes at night. Post-crash care is an opportunity to gather better data to increase our understanding of pedestrian nighttime safety. In this vein, it would be helpful to conduct more quantitative studies that examine the differences between daytime and nighttime pedestrian crashes and use their results to inform safety policies and strategies. It would also be helpful to improve understanding of nighttime pedestrian risk by gathering qualitative data from survivors of pedestrian crashes at night. Surveys and interviews could provide insights into trip purposes, what the drivers and pedestrians were doing and thinking immediately prior to the crash, how each party perceived the roadway environment prior to the crash, and many other aspects of the incident. Ferenchak and Abadi (2021) found that 12% of the increase in nighttime pedestrian fatalities between 2002-2009 and 2010-2017 involved drivers with revoked licenses. Post-crash data collection might help reveal how driver licensing and resources for license recovery intersect with driver behavior leading to nighttime pedestrian crashes.

Other Research to Reduce Nighttime Pedestrian Risk

Two additional categories of research gaps that our literature review revealed are studies that explore contextual influences on nighttime pedestrian risk and practical studies to quantify existing risk at night as well as the effectiveness of specific countermeasures. These studies do not fit cleanly within current SSA categories.

Future Research on Contextual Influences

Contextual influences on nighttime pedestrian risk include neighborhood and built environment characteristics. Many may have indirect effects on pedestrian safety at night, such as influencing driver and pedestrian behaviors or activity levels (i.e., exposure).

• Examine how pedestrian crash risk at night may be related to crime, harassment, and other personal and community security problems at night. Vehicle drivers and pedestrians in high-crime areas with inadequate lighting may drive faster or hurry to cross streets. Pedestrians of racial and ethnic minority groups may be particularly likely to experience harassment or be concerned about their own security at night (Deka et al. 2017). This personal security risk may introduce additional traffic safety risk. This topic has been relatively unexplored in previous research about pedestrian safety at night.
• Investigate rural pedestrian fatalities at night. Do these rural pedestrian fatalities cluster in any particular types of locations? Are there any notable risk factors near Native American reservations and Pueblos?

• Analyze nighttime pedestrian crashes on freeways. Several studies noted that a large number of pedestrian fatalities occur on freeways. However, specific causes for these freeway crashes have not been explored in depth, including the proportion of pedestrian freeway fatalities that occur at night. This research could examine adjacent land uses, possible reasons why the pedestrians were crossing, pedestrians traveling to or from disabled vehicles, unhoused pedestrians, and work-zone pedestrian fatalities at night.
• Understand the role of suburban development in nighttime pedestrian activity. The existing literature typically categorizes locations as either rural or urban, with suburban areas generally included as a subset of the urban environment. Yet, there are often substantive differences in the roadway types, infrastructure design characteristics, presence of pedestrian facilities, and surrounding land uses in suburban areas. How do these differences affect the level of pedestrian activity and exposure? Are crashes and fatalities in suburban areas increasing at a different rate than in denser urban areas? Do these areas require different strategies for pedestrian safety?
• Investigate how changes in the labor market toward more nighttime work may affect pedestrian safety at night. This research could explore differences in nighttime work by job category. Shift workers, or essential workers may be exposed to more risk because they need to travel at night.

Future Practical and Policy-Oriented Research on Nighttime Pedestrian Safety

Fundamentally, safety professionals would be well-served by better data to quantify nighttime pedestrian crash, injury, and fatality risk. Then, more policy-oriented research can be conducted to evaluate nighttime pedestrian safety strategies and practices. However, we found very few studies of efforts specifically intended to improve pedestrian safety at night. This may be because few transportation agencies have attempted to address nighttime pedestrian safety comprehensively (other than pedestrian visibility campaigns). The following types of research would be helpful to expand our understanding of strategies to improve pedestrian safety at night.

• Estimate exposure-based pedestrian injury and fatality rates for daytime and nighttime. After controlling for differences in daytime and nighttime pedestrian activity levels, how much greater is pedestrian risk at night? Answering this question requires better daytime and nighttime pedestrian exposure data. How does the exposure-based ratio of pedestrian nighttime to pedestrian daytime risk vary across communities? Why? Related to exposure, is there more pedestrian activity at night in areas or at roadway crossing locations with higher levels of lighting (Hanson, Noland, and Brown 2013)? How does this impact research on nighttime pedestrian crash rates? What land uses may be more likely to generate pedestrian activity at night? How can pedestrian volume models be refined to represent nighttime pedestrian exposure more accurately?
• Continue to examine which changes in the last fifteen years have contributed most significantly to the increase in U.S. pedestrian fatalities at night. We describe a variety of findings and hypotheses about the increase in US pedestrian fatalities at night since 2009 in Chapter 3 and in the Guide. However, more work, including in collaboration with disciplines like economics and public health, to converge on definitive reasons for this increase would be helpful. Following Ferenchak and Abadi (2021), we suggest that studies examine fatal and severe nighttime pedestrian crashes specifically. Related research comparing the increase in pedestrian fatalities over the fifteen years in the United States to the lack of such trends in peer countries could help further illuminate key factors and interactions to mitigate.
• Quantify the prevalence of pedestrian fatalities in darkness in different countries. Even without data on daytime versus nighttime pedestrian exposure, it would be helpful to understand where the prevalence of pedestrian fatalities at night might be higher or lower. How might the prevalence of nighttime pedestrian fatalities relate to transport and land use system patterns, environmental conditions, or policy actions taken in certain countries?

• Evaluate pedestrian nighttime crash risk between communities and over time. Well-documented pedestrian nighttime crash risk measurements at regular time intervals can help show which safety policies and treatments are most effective at reducing pedestrian risk. Comparative studies across a variety of states and local jurisdictions would help clarify which safety policies and treatments are most appropriate in different community contexts.
• Update design guidelines and safety standards to reflect nighttime pedestrian conditions. It would be particularly helpful for research to be conducted under nighttime conditions for all facility types so that roadway and pedestrian facility design guides can include more complete guidance related to nighttime conditions (as opposed to having a single, separate section about nighttime and lighting). Further, this research could inform new crash modification factors and safety performance functions in the Highway Safety Manual. Ideally, the guidance would discuss lighting quality and maintenance (e.g., how often light fixtures need to be checked and replaced), rather than simply noting the presence or absence of roadway lighting.
• Understand the nighttime pedestrian safety effects of community-level policies and practices. In some places, community members may oppose providing or improving roadway lighting (Markowitz 2022). More qualitative research could be done to understand these community concerns. Other community-level policies may lead to poor maintenance of lighting in low-income areas (e.g., relying on complaint-based systems to identify lighting maintenance issues). Research that quantifies the nighttime pedestrian safety consequences of community-level policies and practices like these would be helpful.
• Given the breath of factors that contribute to pedestrian risk at night, a comprehensive analysis of those factors based in the SSA categories can help clarify the influence and relationships of the various factors to improve the safety of the transportation system for all users. This work can be done at all levels of government as well as within private companies and safety-related organizations.