SafeTREC

Impact of Traffic States on Freeway Collision Frequency

Yeo, Hwasoon
Jang, Kitae
Skabardonis, Alexander
2010

Freeway collisions are thought to be affected by traffic states. To reduce the number of collisions, the study to reveal how the traffic states influence collisions are required. Therefore, the purpose of the paper is to suggest a method to relate traffic states to collision frequency in freeway. We first defined section- based traffic phases showing traffic state of a section using upstream and downstream traffic states: free flow (FF), back of queue (BQ), bottleneck front (BN) and congestion (CT). Secondly, by integrating freeway collision data and traffic data from the California PeMS...

California Traffic Safety Survey 2024: Data Analysis and Comparison with 2010-2023 Survey Data Results

Ewald & Wasserman Research
2024

The 2024 California Traffic Safety Public Opinion Study was conducted on behalf of the California Office of Traffic Safety (OTS) and the Safe Transportation Research and Education Center of UC Berkeley (SafeTREC), using an online self-administered survey. Similar to previous years of the study, the survey panelists were provided through Marketing Services Group, a commercial sample and panel vendor. To ensure a comparable sample disposition to previous years of data collection, six quota groups were set for age and gender groups based on the California census and previous waves of the...

Variations in Teens' Perception of Risk Factors for Teen Motor Vehicle Collision Injuries

Chen, Katherine L.
Cooper, Jill F. MSW
Grembek, Offer, PhD
Henk, Russell H., PE
Tisdale, Stacey M.
2014

Teen drivers, especially males, are known to be at greater risk of being involved in a motor vehicle collision than any other age group. While novice teen drivers’ primary risk factors are commonly known, less is known about what teens perceive as risk factors for peers getting hurt or killed in motor vehicle collisions. This mixed methods study uses survey data from the Teens in the Drivers Seat (TDS) program in California to explore (1) teens' perceived risk factors for motor vehicle collision injury; and (2) the relationship between perceived risks and age, gender, and driving...

Cross-Section Designs for the Safety Performance of Buffer-Separated High-Occupancy Vehicle (HOV) lanes

Jang, Kitae
Kang, Sanghyeok
Seo, Jongwon
Chan, Ching-Yao
2011

High-occupancy vehicle (HOV) lanes have been deployed as a tool for traffic management in urban freeway systems to improve reliability and mobility of trips. As they are planned to traverse crowded urban areas, it is often difficult to acquire sufficient right-of-way for retrofitting HOV lanes to existing freeway systems with recommended cross-sectional design. The present study proposes a methodology to determine the optimal set of cross-sectional design for safety performance by evaluating individual impact of each design element on safety as well as tradeoffs between them. Detailed...

Observational Study of Cell Phone and Texting Use Among California Drivers 2012 and Comparison to 2011 Data

Cooper, Jill F
Ragland, David R
Ewald, Katrin
Wasserman, Lisa
Murphy, Christopher J
2013

This methodological report describes survey research and data collection methods employed for the second Observational Survey of Cell Phone and Texting Use among California Drivers study conducted in 2012. This study was conducted by Ewald & Wasserman Research Consultants (E&W) on behalf of the California Office of Traffic Safety and the Safe Transportation Research and Education Center at University of California at Berkeley. The survey’s goal was to obtain a statewide statistically representative observational sample of California’s cell phone use behaviors, focusing on...

Traffic Safety in Communities of Color

Gantz, Toni
De La Garza, Enrique J.
Ragland, David R.
Cohen, Larry
2003

Over the past half-century in the United States, medical advances, improvements in road and vehicle design, and traffic safety efforts have all helped in reducing traffic-related injury and death. However, research suggests that among the US population, certain ethnic groups, namely African Americans,* American Indians, and Latinos, continue to face higher traffic-related risk. Among all US ethnic groups, motor-vehicle injury is a leading contributor to unnecessary injury and premature death. Improving traffic safety outcomes among these groups could help reduce their overall health...

High Collision Concentration Location: Table C Evaluation and Recommendations

Ragland, David R.
Chan, Ching-Yao
2007

This report describes the research work that was conducted under PATH Task Order 5215 and its extension Task Order 6215, “Methods for Identifying High-Concentration Collision Locations (HCCL).” The subject matter is related to regularly published Caltrans reports, so-called Table C, that are used to screen for and investigate locations within the California State Highway System that have collision frequencies significantly greater than the base or expected numbers when compared to other locations. The accuracy and reliability of such reports are critical as Table C is the basis for follow-...

Driver/Pedestrian Understanding and Behavior at Marked and Unmarked Crosswalks

Ragland, David R.
Mitman, Meghan Fehlig
2007

Pedestrian injuries at crosswalk locations represent a significant problem. In 2002, 22.7 percent of US pedestrians involved in collisions were in a crosswalk at the time of the collision, and over 96% of these occurred at an intersection. Almost all crosswalk collisions resulted in pedestrian injury or fatality (98.6 percent), and about one-third resulted in severe or fatal injury (National Automotive Sampling System (NASS) and General Estimates System (GES) 2002). As the owner of the California State Highway System, Caltrans is responsible for providing access to safe and convenient...

A Review of ITS-Based Pedestrian Injury Countermeasures

Bechtel, Allyson K
Geyer, Judy
Ragland, David R
2003

Crashes between motor vehicles and pedestrians caused at least 4,882 deaths and about 78,000 injuries in 2001 in the United States. In recognition of these troubling statistics, many public and private institutions look to Intelligent Transportation Systems (ITS) technologies. Few resources are available to provide a comprehensive summary of the effectiveness of these options. This report reviews previous scientific evaluation of red light enforcement cameras, illuminated walk signal push buttons, automated pedestrian detection systems for traffic signals, flashing crosswalk lights,...

Pedestrian Volume Modeling for Traffic Safety and Exposure Analysis:

Raford, Noah
Ragland, David R.
2005

This paper examines three types of pedestrian volume models in light of their usefulness for estimating pedestrian exposure for pedestrian safety research. The need for pedestrian flow data as part of pedestrian exposure and safety analysis is outlined, and the background of each type of model is discussed. It then selects the space syntax network analysis model to estimate pedestrian volumes for the city of Boston, Massachusetts. It was found that the model was able to accurately predict pedestrian flows (r-squared 0.81, p-value < 0.0001) after incorporating distance to transit...