Safety

Assessing the Impact of Vehicle Weight on Road Safety

Banerjee, Ipsita
Julia Griswold
2026

Since 2009, pedestrian fatalities have risen by 80%, which mirrors the increase in the average weight of vehicles accompanying the rising popularity of SUVs and pickup trucks. Additionally, many modern safety and environmental technologies, including those in electric vehicles, contribute to increased vehicle weight. Heavier vehicles generate greater kinetic energy, which can lead to a higher risk of fatalities and serious injuries in crashes. This research synthesis examines the relationship between vehicle weight, design, and safety for road users, particularly pedestrians. However, not...

A Unified Framework for Safe System Implementation

Mitman, Meghan
Julia Griswold
Banerjee, Ipsita
Carpenter, Rachel
2026

The Safe System Approach (SSA) is a foundational element of US transportation safety policy, yet its implementation has often remained siloed, reactive, and disconnected from broader systemic change. To advance Vision Zero goals and institutionalize safety across disciplines, we propose a Unified Safe System Implementation Framework for state and local transportation agencies that brings together global best practices in public health, context-sensitive design, and kinetic-energy risk management. The framework addresses three core insights: the centrality of exposure, severity, and...

Sexual Exploitation and Safety in Ridehailing: Rider Perceptions, Precautionary Behaviors, Associations with Victimization Characteristics, Taxi Comparisons and the Prevention Mismatch

Koss, Mary P.
McGray, Taren
Peterson, Zoe D.
Tillewein, Heather
Susan Shaheen
2026

Uber, Lyft, and some taxi safety systems include driver screening, trip monitoring, emergency tools, complaint response, and driver deactivation. Their safety reports historically emphasized five of 21 industry-wide sexual-misconduct and sexual-assault categories. After Lyft disclosed all 21 in May 2026, its 2020–2022, the total was approximately 40 times greater. We examined whether ridehailing-related victimization history was associated with riders’ safety concerns, precautionary burden, company safety-feature use, and reporting. A quota-based opt-in survey of 638 U.S. ridehailing users...

Independent and Interactive Association of Reported Impairment in Fatal Crashes Among Young California Drivers: A Cross-Sectional Analysis

Lotito, Ainsley
Vaca, Federico E.
Li, Melody S.
Hu, Siwei
Hill, Linda
Julia Griswold
Li, Kaigang
2026

Objective
To examine the independent and combined associations of reported alcohol, drug, and fatigue involvement with crash fatality among young drivers in California.
Methods
Using 2016-2024 injury crash data from the University of California, Berkeley Transportation Injury Mapping System, we performed logistic regression to examine the association between reported driver impairment and crash fatality among drivers aged 15-24. Additive interaction was assessed using binary impairment indicators and interaction terms. Relative excess risk due to interaction (RERI) and 95%...

Unequal Risk: Longitudinal Observation of Socioeconomic Disparities and Pedestrian Mortality Patterns in Cali, Colombia

Villaveces, Andres
Fox, Lani
Daniel Rodriguez
Bangdiwala, Shrikant I.
Ortega, Delia
Serre, Marc
2026

Household locations of pedestrian injuries and fatalities are disproportionately concentrated in lower socioeconomic neighborhoods, reflecting deep-rooted disparities in urban infrastructure, pedestrian exposure, and traffic safety. This study analyzes the relationship between socioeconomic levels and pedestrian incidents in Cali, Colombia, focusing on both the residential locations of injured individuals and the physical locations of fatalities. By separately examining injury residences and fatality locations, we begin to investigate how socioeconomic disparities influence both who is...

Autonomous Vehicle Safety Performance in Mixed Traffic: Insights from NHTSA Crash Data

Mahdinia, Iman
Julia Griswold
Erz, Tristan
2026

The safe deployment of autonomous vehicles (AVs) depends on the ability of automated driving systems (ADS) to handle rare, complex, and safety-critical “edge cases.” This study develops a novel framework for identifying and analyzing such scenarios using the National Highway Traffic Safety Administration (NHTSA) ADS crash dataset. Two complementary approaches are applied. First, large language models (LLMs) are used to directly analyze crash narratives, identifying edge cases through high-risk keyword and phrase detection and anomaly-based rarity analysis. Second, LLMs are employed to...

Lead with the Helmet

Adam Cohen
Martin, Elliot
2016

Bikesharing systems offer access to a shared network of bicycles deployed on public streets. Present-day systems use information technology to manage user interactions, and to manage the fleet of bicycles. Bikesharing systems can be station-based, in which users access bicycles at kiosks with automatic locks, or free-floating, in which self-locking bicycles are accessed within a geo-fenced area. Bikesharing generally permits point-to-point travel, providing users with flexibility to use the service as a first-mile/last-mile connection or as its own means from origin to destination....

Bikesharing and Bicycle Safety

Martin, Elliot
Adam Cohen
Susan Shaheen
Botha, Jan
2016

The growth of bikesharing in the United States has had a transformative impact on urban transportation. Major cities have established large bikesharing systems, including Boston, Chicago, Denver, Minneapolis-Saint Paul, New York City, Salt Lake City, the San Francisco Bay Area, Seattle, Washington DC, and others. These systems began operating as early as 2010, and no fatalities have occurred within the US as of this writing. However, three have happened in North America—two in Canada and one in Mexico. Bikesharing has some qualities that appear inherently unsafe for bicyclists. Most...

Heterogeneity in Flood Hazard Exposure in 363 Latin American Cities

Xu, Jinwen
Dronova, Iryna
Tinoco, Vicente
Kephart, Josiah L.
Bilal, Usama
Sanchez, Brisa N.
Diez Roux, Ana V.
Gouveia, Nelson
Sarmiento Dueñas, Olga Lucia
Vives Vergara, Alejandra
Alazraqui, Marcio
Daniel Rodriguez
2026

Flooding is among the costliest natural disasters worldwide, yet how riverine flood hazard is distributed within cities remains poorly quantified, particularly across socially vulnerable population groups. Climate change is intensifying flood magnitude, duration, and frequency, raising concerns that existing inequalities in flood exposure will widen. Using data from the multi-country SALURBAL project, we assess disparities in riverine flood hazard among residents of 363 cities across 9 Latin American countries. We develop two city-level indicators, the Exposure Deviation Index (EDI) and...

Jaywalking in California: History, Pedestrian Safety Trends, Law Enforcement Patterns, and Decriminalization Legislation

Santos, Mike
Lutzker, Liza
Julia Griswold
2026

This report investigates jaywalking laws in connection with traffic safety, racial equity, and street design, focusing on California. It traces the concept of "jaywalking" to an early 20th-century auto industry campaign to shift safety responsibility from drivers to pedestrians. By analyzing national and California pedestrian injury and fatality data (2009– 2022) alongside California Racial and Identity Profiling Act (RIPA) police stop data (2018–2022), the study describes demographic disparities in both pedestrian crashes and law enforcement of jaywalking. It also documents recent...