Data collection

Attributable risk of alcohol and other drugs for crashes in the transit industry

Cunradi, Carol B.
Ragland, David R.
Greiner, Birgit A.
Klein, M.
Fisher, June M.
2005

Objective: To estimate the impact of employee alcohol and drug use on crashes in the transit industry from 1995–2000.

Design: Secondary analysis of federally mandated post crash and random alcohol and drug testing results.

Setting: The US transit industry.

Subjects: Transit industry employees.

Main outcome measures: Relative risk (RR), population attributable risk (PAR), and population attributable risk percentage (PAR%).

Results: For alcohol testing, the estimated PAR% ranged...

Design of Alert Criteria for an Intersection Decision Support System

Shladover, Steven E.
Vanderwerf, Joel
Ragland, David R.
Chan, Chin-Yao
2005

This paper describes the design and preliminary evaluation of the criteria for alerting drivers to a specific set of intersection hazards. The research is being conducted as part of the development of an intersection decision support (IDS) system that uses the sensing and computational technologies of infrastructure-based intelligent transportation systems. The IDS system under consideration is intended to help drivers avoid conflicts with oncoming traffic when they are making left turns under a permissive (i.e., unprotected) green signal. These conflicts account for a significant...

Physical workload, ergonomic problems, and incidence of low back injury: A 7.5-year prospective study of San Francisco transit operators

Krause, Niklas
Rugulies, Reiner
Ragland, David R.
Syme, S. Leonard
2004

Background: The etiologic role of biomechanical factors for low back injury (LBI) needs to be confirmed in prospective studies that control for psychosocial factors.

Methods: Complete baseline information on 1,233 vehicle operators was gathered during medical examinations and by questionnaire. First LBI during 7.5 years of follow-up was ascertained from insurance records. Hazard ratios and etiologic fractions were analyzed with Cox regression models stratified by injury severity and controlling for age, sex, height, weight, ethnicity, and biomechanical and...

Observations of Driver Time-Gap Acceptance at Intersections in Left-Turn Across-Path Opposite-Direction Scenarios

Chan, Ching-Yao
Ragland, David R.
Shladover, Steven E.
Misener, James A.
Marco, David
2005

Intersection collision warning systems can potentially reduce the number of collisions and associated losses. A critical design aspect of these systems is the selection of warning criteria, which represent a set of conditions and parameters under which the decision and the timing to issue warnings are determined. Proper warning criteria allow the generation of timely signals for drivers while minimizing false and nuisance alarms. We describe the development of a methodology to observe and analyze the selection of time gaps exhibited by driver behaviors in a real-world setting. The data...

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...

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...

Evaluating the Performance of Network Screening Methods for Detecting High Collision Concentration Locations on Highways

Kwon, Oh Hoon
Park, Min Ju
Yeo, Hwasoo
Chung, Koohong
2012

This paper documents findings from evaluating performances of three different methods for segmenting freeway sites for the purpose of identifying high collision concentration locations: Sliding Moving Window (SMW), Peak Searching (PS) and Continuous Risk Profile (CRP). The traffic collision data from sites segmented in each method under two different roadway definitions were used to estimate excess expected average crash frequency with Empirical Bayes adjustment with respect to two different sets of Safety Performance Functions (SPFs). The estimates from each of the methods were then used...

Alcohol, Stress-Related Factors, and Short-Term Absenteeism Among Urban Transit Operators

Cunradi, Carol B.
Greiner, Birgit A.
Ragland, David R.
Fisher, June M.
2005

Transit operators, relative to workers in many other occupations, experience high levels of work-related stress, as documented through neuroendocrine elevations on the job vis-à-vis resting states (J Occup Health Psychol. 1998;3:122–129). Previous research suggests that self-reported job stress is associated with higher levels of alcohol consumption among transit operators (Alcohol Clin Exp Res. 2000;24:1011–1019) and with absenteeism (Working Environment for Local...

On The Legal Deterrence Of Pedestrian Hit-and-Run Collisions

Grembek, Offer
Griswold, Julia B.
2012

Hit-and-run collisions—those in which a driver involved in the collision leaves the scene before the arrival of law enforcement officials—are a unique type of traffic violation because the driver's decision is a question of damage control rather than damage prevention. To reduce hitand-run violations, individual state laws impose legal sanctions to deter drivers from leaving the collision scene prematurely. Deterrence Theory dictates that compliance with laws is associated with the certainty, severity, and swiftness of punishment. The purpose of this study is to explore the deterrent...

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...