Data collection

Evaluation of Wet Weather Accident Causation Criteria

Oh, Soonmi
Ragland, David R.
Chan, Ching-Yao
2008

This report documents findings from analysis of traffic collision data from sites that display high collision rates only under wet pavement conditions. These sites were selected using Caltrans safety engineers’ field reports, Wet Table C “investigation required” locations, and a new approach called Continuous Risk Profile (CRP). The geometric features at the sites were studied via field visits and review of as-built plans. Rapid spatial changes (i.e., vertical and horizontal curve in short distance), narrower lane width, lack of median, and wider total freeway width were some of the...

Safety Evaluation of High-Occupancy Vehicle (HOV) Facilities in California

Ragland, David R.
Oh, Soonmi
Chan, Ching-Yao
2008

This report documents findings from analysis of traffic collision data from sites that display high collision rates only under wet pavement conditions. These sites were selected using Caltrans safety engineers’ field reports, Wet Table C “investigation required” locations, and a new approach called Continuous Risk Profile (CRP). The geometric features at the sites were studied via field visits and review of as-built plans. Rapid spatial changes (i.e., vertical and horizontal curve in short distance), narrower lane width, lack of median, and wider total freeway width were some of the...

Attribution of functional limitation to cancer decreases in the year following breast cancer diagnosis in older patients

Sehl, Mary E.
Satariano, William A.
Ragland, David R.
Reuben, David B.
Naeim, Arash
2008

Objectives: To examine the prevalence of self-reported functional limitations in a breast cancer population, identify whether these reported limitations are attributed to breast cancer versus other coexisting illnesses, and examine how this attribution changes over time from early in treatment to 9 months later.

Design: Longitudinal, observational study.

Setting: Community dwelling adults in Detroit metropolitan area. Participants: 2033 participants (1011 breast cancer patients, 1022 controls) aged 40–84 years.

Measurements: Participants were asked about each of 23...

Crosswalk Confusion: More Evidence Why Pedestrian and Driver Knowledge of the Vehicle Code Should Not Be Assumed

Mitman, Meghan F.
Ragland, David R.
2014

Traffic safety researchers have long argued that driver behavior outweighs physical elements (such as road design) as a causal factor in motor vehicle collisions. A fundamental causal component of pedestrian—vehicle collisions is also behavior: that of the driver and that of the pedestrian. One determinant of this behavior may be whether the driver, the pedestrian, or both understand the motor vehicle code, which demarcates the right-of-way in pedestrian-vehicle interactions. That is, inappropriate or unlawful behavior may occur because the law is not understood or is misunderstood....

Spatiotemporal Analysis of Macroscopic Patterns of Urbanization and Traffic Safety: A Case Study in Sacramento County, California

Sanghyeok, Kang
Spiller, Margot
Jang, Kitae
Bigham, John M.
Seo, Jongwon
2012

This study provides a preliminary investigation into the relationship between urbanization and trafficcollisions by analyzing the spatial patterns in Sacramento County, California from 1998 to 2008 using urban land classifications and traffic collision data. The ArcGIS directional distribution tool was used to create standard deviational ellipses to investigate the distributional trend of urban land and traffic collisions over time. Statistical outputs representing changes of geographical centroids, elliptical areas, and standard distances (long and short axes) were then...

Transportation and Health: Policy Interventions for Safer, Healthier People and Communities

Ragland, David R.
Orrick, Phyllis
2011

The public road system in the U.S. is the world’s busiest, sustaining more than 3 trillion vehiclemiles of travel each year on a network of more than 4 million miles of roads and highways. It has had enormous positive impacts on U.S. society, driving economic growth and innovation, providing mobility and opportunity to its users, and helping the U.S. maintain its global economic competitiveness. This system was built with a focus on motor vehicles; only recently has substantial funding and attention been given to transit, walking, and bicycling. There is still a huge disparity in how we...

Pedestrian and Bicyclist Safety Effects of the California Safe Routes to School Program

Gutierrez, Nicolas
Orenstein, Marla
Cooper, Jill F.
Rice, Thomas M.
Ragland, David R.
2008

In the last decade, there has been an increased focus in California on encouraging children to walk and bicycle to school safely. In 1999, the California Legislature created the Safe Routes to School (SR2S) program, authorizing issuance of a competitive grant process for roadway construction projects. There has been an overall decline in the numbers of child pedestrian/bicyclist collisions in California as a whole. When compared with the control areas, the SR2S project areas did not show a greater decline in numbers of collisions. However, it is likely that the number of children...

The Marked Crosswalk Dilemma: Uncovering Some Missing Links in a 35-Year Debate

Mitman, Meghan F.
Ragland, David R.
Zegeer, Charles V.
2008

Largely in response to several landmark safety studies, as an official or unofficial policy, many agencies across the U.S. have elected to remove marked crosswalks at uncontrolled intersections, or have shown resistance to installing them in the first place. This approach results in unacceptable pedestrian mobility restrictions, yet such restrictions are often not considered in policy-making. As such, there is a need for roadway system owners to develop strategic safety guidelines to address the marked crosswalk dilemma.

Since 2005, the UC Berkeley Traffic Safety...

Safety Performance of Experimental Pavement Types in California Using Before-and-After Comparisons

Oh, Soonmi
Ragland, David R.
Chan, Ching-Yao
2010

This study focused on safety performance of new pavement surface types. Open graded or coarse- textured roadway surfaces are advisable for high-speed, wet-weather traffic conditions. They provide drainage relief at the tire-pavement interface, reduce the steepness of the speed gradient, decrease the likelihood of hydroplaning, minimize splash and spray, reduce the glare from wet pavements, and improve high-speed skid resistance. Before-and-after comparisons using historical collision data from California Traffic Accident Surveillance and Analysis System (TASAS) were conducted to...

Traffic Injury on Tribal Lands in California

Ragland, David R.
Bigham, John M.
Oum, Sang Hyouk
Chen, Katherine L.
Felschundneff, Grace
2014

There is a disproportional risk of motor vehicle death and injury among American Indian/Alaska Native (AI/AN) populations in the United States. As home to the nation’s largest population of AI individuals, it is vital that California develop a better understanding of the factors contributing to this risk to guide the development and implementation of interventions to improve traffic safety for this population on the nearly 100 Rancherias and reservations in the state. However, there is very little data about the numbers and types of collisions, and driver and environmental factors...