Training and education

Surrogate safety measure for evaluating rear-end collision risk related to kinematic waves near freeway recurrent bottlenecks

Li, Zhibin
Ahn, Seongchae
Chung, Koohong
Ragland, David R.
Wang, Wei
Yu, Jeong Whon
2013

This study presents a surrogate safety measure for evaluating the rear-end collision risk related to kinematic waves near freeway recurrent bottlenecks using aggregated traffic data from ordinary loop detectors. The attributes of kinematic waves that accompany rear-end collisions and the traffic conditions at detector stations spanning the collision locations were examined to develop the rear-end collision risk index (RCRI). Together with RCRI, standard deviations in occupancy were used to develop a logistic regression model for estimating rear-end collision likelihood near freeway...

Using Geographically Weighted Poisson Regression for county-level crash modeling in California

Li, Zhibin
Wang, Wei
Liu, Pan
Bigham, John M.
Ragland, David R.
2013

Development of crash prediction models at the county-level has drawn the interests of state agencies for forecasting the normal level of traffic safety according to a series of countywide characteristics. A common technique for the county-level crash modeling is the generalized linear modeling (GLM) procedure. However, the GLM fails to capture the spatial heterogeneity that exists in the relationship between crash counts and explanatory variables over counties. This study aims to evaluate the use of a Geographically Weighted Poisson Regression (GWPR) to capture these spatially varying...

Promoting Research Results and New Technologies: Making the Case for Accelerated Deployment

Andrews, Stephen
Madanat, Samer
Ragland, David R.
West, Thomas
2011

Deploying innovations in transportation products and services to Stage 5 of the product development process represents a growing challenge for the California Department of Transportation’s (Caltrans) Division of Research and Innovation (DRI). This technical agreement focused on communicating the promise of select products and services through outreach and promotion in an effort to gain broader knowledge, understanding, and acceptance of the innovations leading to their adoption by Caltrans and the transportation community at-large. Attention is given to outreach and promotion of ROSA-CRP...

Applying Safety Improvements to Fleet Vehicles

Cooper, Douglas L.
Sharafsaleh, Mohammad A.
Ragland, David R.
Begley, Loida
Kim, Yong Hee
Jin, Eui Jae
2007

The safety of both employees and the motoring public is of paramount importance to Caltrans, resulting in a continuing effort to improve the operating vehicle fleet. The potential safety changes that are the focus of this project are those that involve safety equipment enhancement over and above the original specifications for the vehicle or outside of the scope of the original equipment design or purpose, such as rear view backup video cameras. The motivation for this project was Division of Equipment (DOE) managers' need for an objective strategy to address safety equipment deployment...

Occupational stressors and hypertension: A multi-method study using observer-based job analysis and self-reports in urban transit operators

Greiner, Birgit A.
Krause, Niklas
Ragland, David R.
Fisher, June M.
2004

This multi-method study aimed to disentangle objective and subjective components of job stressors and determine the role of each for hypertension risk. Because research on job stressors and hypertension has been exclusively based on self-reports of stressors, the tendency of some individuals to use denial and repressive coping might be responsible for the inconclusive results in previous studies. Stressor measures with different degrees of objectivity were contrasted, including (1) an observer-based measure of stressors (job barriers, time pressure) obtained from experts, (2) self-reported...

Pedestrian and Bicycle Safety Evaluation in a SMART Corridor

Ragland, David R.
O’Connor, Terri
2007

The San Pablo/I-80 corridor is a “SMART” transportation corridor that extends about 20 miles along the eastern shore of the San Francisco Bay. The corridor uses Intelligent Transportation System (ITS) technologies to increase and enhance transportation mobility.

The goal of the SMART Corridor Plan was to improve vehicle mobility throughout the corridor. Since the plan focused almost exclusively on vehicular traffic, achieving these goals has the potential to raise the risk of injury to pedestrians and bicyclists without thorough analysis of the overall effects of the SMART corridor...

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....

Addressing Inappropriate Driver Behavior at Rail-Highway Crossings

Cooper, Douglas L.
Ragland, David R.
2008

Driver behavior at rail highway crossings has been the subject of numerous studies, most of which show that violations are relatively commonplace. The focus of this paper will be on those drivers who drive around fully descended gates. Drivers commonly misjudge the speed and distance of trains. They must make a decision about the time remaining before the train arrives based on sensory signals as well as non-sensory factors such as expectations and motivation. At a gated crossing, where drivers have been alerted to the imminent danger by lowered gates, there is more to be gained by...

Removing Barriers for Seniors at Transit Stops and Stations and the Potential for Transit Ridership Growth

Babka, Rhianna JoIris
Zheng, Joseph
Cooper, Jill F.
Ragland, David R.
2008

As the baby boomer generation ages there is an increased need for older adult sensitive transportation. Currently a small percentage of older adults utilize public transit; however, the utilization rates are likely to increase as the corresponding population of older adults increases. Older adults are a diverse population and it is likely that future generations of older adults will require a wider range of transit options.

The current research addresses (i) barriers for older adults at transit stops and stations, and (ii) older adult public transit habits and...