Injury Exposure

A Multidimensional Clustering Algorithm for Studying Fatal Road Crashes

Fishbain, Barak
Grembek, Offer

Road fatalities are rare outcomes of events that occur in a small time-space region. Although the exact chain of events for each fatality is unique, there are inherent similarities between road fatalities. The science of road safety is dedicated to identifying such similarities, mainly using statistical analysis tools. Researchers typically analyze patterns that emerge over space, such as hot-spot studies, or patterns that emerge over time, such as before-after studies. Traffic research enumerates 84 parameters that characterize a road fatality. A vast number of papers have tried to...

SafeTREC Co-Director Offer Grembek talks about Safe Systems & Speed with the Vision Zero Network

July 21, 2020

This month, SafeTREC Co-Director and Collaborative Sciences Center for Road Safety (CSCRS) Associate Director Offer Grembek was featured in "Talking with Offer Grembek, Transportation Researcher, about Safe Systems & Speed" the latest entry of the Vision Zero Network's People Behind the Progress Series. In this conversation...

A behavioral modeling approach to bicycle level of service

Griswold, Julia B.
Yu, Mengqiao
Victoria Filingeri
Grembek, Offer
Joan Walker

Bicycle level of service (LOS) measures are essential tools for transportation agencies to monitor and prioritize improvements to infrastructure for cyclists. While it is apparent that different types of cyclists have varying preferences for the facilities on which they ride, in current research and practice, measures are used that are either insufficiently quantitative and empirical or lack cyclist segmentation. In this study, we conducted a detailed survey on cyclist habits, preferences, and user experience, capturing responses to videos of a bicycle traveling on road segments in the San...

The Association between Booster Seat Use and Risk of Death Among Motor Vehicle Occupants aged 4–8: A Matched Cohort Study

Rice, Thomas M.
Anderson, Craig L.
Lee, A. S.

Objective: To estimate the effectiveness of booster seats and of seatbelts in reducing the risk of child death during traffic collisions and to examine possible effect modification by various collision and vehicle characteristics.

Methods: A matched cohort study was conducted using data from the Fatality Analysis Reporting System. Death risk ratios were estimated with conditional Poisson regression, bootstrapped coefficient standard errors, and multiply imputed missing values using chained equations.

Results: Estimated death risk ratios for booster seats used with seatbelts...

Geocoding Police Collision Report Data from California: A Comprehensive Approach

Bigham, John M.
Rice, Thomas M.
Pande, Swati
Lee, Junhak
Park, Shin Hyoung
Gutierrez, Nicolas
Ragland, David R.


Collision geocoding is the process of assigning geographic descriptors, usually latitude and longitude coordinates, to a traffic collision record. On California police reports, relative collision location is recorded using a highway postmile marker or a street intersection. The objective of this study was to create a geocoded database of all police-reported, fatal and severe injury collisions in the California Statewide Integrated Traffic Records System (SWITRS) for years 1997-2006 for use by public agencies.


Geocoding was completed with a multi-step...

The Relative Vulnerability Index: A Framework for Evaluating Multimodal Traffic Safety

Grembek, Offer

The multimodal transportation network includes a mix of inherently different modes. In addition to differences in price, range, and comfort of travel, these modes differ in mass and velocity, which correspond to different orders of magnitude in the kinetic energy carried. This discrepancy in kinetic energy affects both the level of protection of each mode, and the level of damage it can inflict on users of other modes. Unfortunately, accounting for both sides of a crash is often overlooked. While the quantities and variables of collected data continue to increase, the analyses conducted...

Alcohol Consumption and Incidence of Workers' Compensation Claims: A 5-Year Prospective Study of Urban Transit Operators

Ragland, David R.
Krause, Niklas
Greiner, Birgit A.
Holman, Barbara L.
Fisher, June M.
Cunradi, Carol B.

Numerous studies have linked alcohol impairment on the job to occupational injury. Few studies have looked at the association of nonwork drinking and occupational injury. This study examines first workers' compensation claims after a baseline assessment of alcohol consumption and other occupational variables in 1836 transit operators participating in a medical examination for driver's license renewal. A proportional hazard model was used for the analysis.

Individuals with higher alcohol consumption were more likely to be male, have more years of driving, and have a higher job-...

Traffic Volume and Collisions Involving Transit and Nontransit Vehicles

Ragland, David R.
Hundenski, Ronald J.
Holman, Barbara L.
Fisher, June M.

This study reports an analysis of collisions occurring between public transit vehicles operated by the San Francisco Municipal Railway System (Muni), the public transit agency for the City of San Francisco, and nontransit vehicles. The analysis, focusing on weekday collisions during 1987, demonstrated a strong association between hourly transit collisions rates and hourly traffic volume. The collision rate varied from 0.01 per 1,000 Muni vehicle-hours of operation during the interval 5 a.m. to 6 a.m., a time of very low traffic...

Traffic Safety Among Latino Populations in California: Current Status and Policy Recommendations

Cooper, Jill F.
Wilder, Tammy R.
Lankina, Elena
Geyer, Judy A.
Ragland, David R.

This report summarizes the information gained from two community forums held in Latino communities in California, provides an analysis of trends in injury and demographic data, and reviews best practices for increasing safety and preventing injury in Latino populations. It highlights pressing traffic safety needs and presents recommendations. It is our goal that this report will serve as a prototype for policy, enforcement and program development to address traffic safety issues for Latinos in California.