Safety

The Continuous Risk Profile Approach for the Identification of High Collision Concentration Locations on Congested Highways

Chung, Koohong
Ragland, David R.
Madanat, Samer
Oh, Soon Mi
2009

This paper documents a new method for monitoring traffic collision data from continuous roadway facilities to detect high collision concentration locations. Many existing methods for detecting collision concentration locations require segmentation of roadways and assume traffic collision data are spatially uncorrelated, resulting in both false positives (i.e., identifying sites for safety improvements that should not have been selected) and false negatives (i.e., not identifying sites that should have been selected). The proposed method does not require segmentation of roadways; spatial...

Giving cycling the green light: An overview of transportation in Ireland and the design of the National Cycle Network

Manton, Richard
2013

Similarly to the US, driving a car to work continues to gain ground in Ireland and the country is presented with major challenges in environment and health as a consequence. In safety, at least, Ireland has had some major successes. In 40 years, the number of fatalities has fallen from 640 to 162, a drop of 75%. Such improvements in road safety have been attributed to a combination of education, enforcement and engineering. Pedestrian and cyclist fatalities have each fallen by 66% in 20 years, however, this could be attributed to the lower numbers of people walking and cycling....

Performance Measures for Complete, Green Streets: Initial Findings for Pedestrian Safety along a California Corridor

Sanders, Rebecca
Macdonald, Elizabeth
Anderson, Alia
Ragland, David R.
Cooper, Jill F.
2011

This paper reports on research conducted by the Safe Transportation Research and Education Center and sponsored by the California Department of Transportation (“Caltrans”) to establish performance measures for pedestrian and bicycle safety and mobility along urban arterials. Although historically focused on motorized vehicle mobility, Caltrans has recently joined in a national trend to incorporate non-motorized transportation and community-level outcomes into transportation decision-making frameworks, an approach known as "Complete Streets." Recognizing that its current performance...

Pedestrian Counting Methods at Intersections: a Comparative Study

Diogenes, Mara Chagas
Greene-Roesel, Ryan
Arnold, Lindsay S.
Ragland, David R.
2007

Resources for implementing countermeasures to reduce pedestrian collisions in urban centers are usually allocated on the basis of need, which is determined by risk studies. They commonly rely on pedestrian volumes at intersections. The methods used to estimate pedestrian volumes include direct counts and surveys, but few studies have addressed the accuracy of these methods. This paper investigates the accuracy of three common counting methods: manual counts using sheets, manual counts using clickers, and manual counts using video cameras. The counts took place in San Francisco. For the...

Identification of High Collision Concentration Locations Under Wet Weather Conditions

Hwang, Taesung
Chung, Koohong
Ragland, David
Chan, Ching-Yao
2008

This paper focuses on identifying roadway locations that display high collision rates only under wet pavement condition. A unique approach of screening and identifying such locations, called the continuous risk profile (CRP) method, was utilized for this analysis The CRP method was applied to over 380 miles of freeways in the San Francisco Bay Area to identify sites that display high collision rates only under wet pavement condition. Twelve of the identified sites were then further investigated to determine if there are any common geometric, topographic, or site conditions that may...

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...