Safety

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...

Best Practices for the Public Management of Electric Scooters

Karl Reinhardt
Elizabeth Deakin
2020

This research projects evaluates the social, environmental, and safety impacts of shared electric scooters (e-scooters)’ through a literature review, a nationwide scan of state and local laws and regulations, and a case study of Oakland’s experience with e-scooters, including an analysis of the city’s user survey and our own in-depth interviews. E-scooters offer an enjoyable, low-cost travel option, but are used mainly by young, affluent, white males. To improve equity, cities are requiring e-scooter rental companies to serve low-income and minority communities and some further mandate...

Strategies for Improving Pedestrian Safety: Cases from Jalisco and Michoacán, Mexico

Carolyn McAndrews
Elizabeth Deakin
Alfredo Celis De la Rosa
2008

In developing countries, the growing use of autos is creating a clash with pedestrians. Pedestrian-vehicle collisions clearly have immediate negative consequences on public health. In the longer run, if walking is not safe, comfortable, and convenient, it is likely to decline as a mode of travel in countries where households and individuals increasingly have the means to choose alternatives. Even so, most people will continue to walk for many trips, and with increasing motorization will be at risk of harm unless the safety and comfort of the walking environment is improved. We use data...

Towards Automated Air Traffic Safety Assessment Around Non-Towered Airports Using Large Language Models

Darrell, Torsten
Ghazanfari, Mahyar
Kam, Jordan
Alexandre Bayen
Tabrizian, Amin
Wei, Peng
2026

We investigate frameworks for post-flight safety analysis at non-towered airports using large language models (LLMs).

Optimal-Velocity-Based Car-Following Model With Control Lyapunov-Barrier Functions

Yeo, Yuneil
Bonsanto, Pietro
Miti, Masuma Mollika
Maria Laura Delle Monache
2026

This paper develops an optimization-based control framework for a microscopic nonlinear car-following model. The controller is obtained from a Control Lyapunov Function-Control Barrier Function-Quadratic Programming framework that enforces stability, velocity feasibility, and collision-avoidance constraints while minimizing control effort. The resulting controller mitigates the limitations of the spacing-dependent singularity-based car-following models and guarantees closed-loop safety and stability.

Extreme Heat Disproportionately Increases Severe Road Traffic Crashes in High Conflict Settings and Among Vulnerable Road Users in California

Hsu, Cheng-Kai
Quistberg, D. Alex
Pérez-Ferrer, Carolina
Daniel Rodriguez
2026

Emerging evidence suggests that extreme heat elevates road-traffic injuries, undermining international road safety efforts like Vision Zero as global warming intensifies. However, the mechanisms underlying heat-related crashes remain poorly understood, with limited research linking heat exposure to specific crash types that may be driven by heat-induced unsafe road behaviors. Here, we analyzed temperature data and police-reported crash records—including detailed crash scene information—from 177 California cities (2012–2023) using a time-stratified case-crossover design, examining...

Trends in Alcohol-involved Crashes Among Young California Drivers Before, During and After the COVID-19 Pandemic

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

Objectives: To examine changes in alcohol-involved traffic crash rates among young drivers in California during and following the COVID-19 pandemic.
Methods: We conducted a cross-sectional study of alcohol-involved crashes among drivers aged 15–24 using data from the University of California, Berkeley Transportation Injury Mapping System (2016–2024). The primary exposure was COVID-19 policy period (pre-, during-, and post-pandemic). Annual crash rates per 100,000 population were calculated, and Quasi-Poisson regression models estimated rate ratios (RRs) comparing COVID-19 periods,...

Ambient Temperature and Homicide Mortality in 307 Latin American Cities: A Case Time Series Design

Moraes, Sara Lopes de
Daniel Rodriguez
Schinasi, Leah H.
Kephart, Josiah L.
Dronova, Iryna
Bakhtsiyarava, Maryia
Caiaffa, Waleska Teixeira
Rangel-Moreno, Karla
Rodriguez-Villamizar, Laura A.
O’Neill, Marie
de Lima Friche, Amélia Augusta
Herrera López, Astrid Berena
Alazraqui, Marcio
Magalhães, Amanda Silva
Sarmiento, Olga L.
Sanchez, Brisa N.
Gouveia, Nelson
2026

Homicide is a leading cause of death in many countries, and growing evidence suggests that short-term variations in ambient temperature, especially high temperatures, might be associated with higher risk of homicide. Latin America is the most violent region in the world, yet knowledge about the linkages between ambient temperature and homicide mortality in the region remains limited. We conducted a case time series design using conditional quasi-Poisson and distributed lag non-linear models to estimate short-term associations (0-7 lag days) between daily mean temperature and homicide...

Unsupervised Anomaly Detection in Multi-Agent Trajectory Prediction via Transformer-Based Models

Lyu, Qing
Fu, Zhe
Alexandre Bayen
2026

Identifying safety-critical scenarios is essential for autonomous driving, but the rarity of such events makes supervised labeling impractical. Traditional rule-based metrics like Time-to-Collision are too simplistic to capture complex interaction risks, and existing methods lack a systematic way to verify whether statistical anomalies truly reflect physical danger. To address this gap, we propose an unsupervised anomaly detection framework based on a multi-agent Transformer that models normal driving and measures deviations through prediction residuals. A dual evaluation scheme has been...