Evaluation

Driving Cessation and Increased Depressive Symptoms

Ragland, David R.
Satariano, William A.
MacLeod, Kara E.
2003

Background. To understand the consequences of driving cessation in older adults, the authors evaluated depression in former drivers compared with active drivers.

Methods. Depression (as assessed using the Center for Epidemiological Studies Depression Scale), driving status, sociodemographic factors, health status, and cognitive function were evaluated for a cohort of 1953 residents of Sonoma County, California, aged 55 years and older, as part of a community-based study of aging and physical performance. The authors reinterviewed 1772...

Problems With Vision Associated With Limitations or Avoidance of Driving in Older Populations

Satariano, William A.
MacLeod, Kara E.
Kohn, Theodore E.
Ragland, David R.
2004

Objectives. This report examines the role of (a) disease processes affecting vision, (b) reported troubles with vision, (c) physical symptoms affecting the eyes, and (d) objective measures in reported driving limitation due to problems with eyesight among older drivers.

Methods. Data for this study (N 1⁄4 1,840) were obtained from participants in a community-based study of aging and physical performance in people age 55 or older in the city of Sonoma, California. Each of 16 visual conditions was...

HOV Lane Configurations and Safety Performance of California Freeways – An Investigation of Differential Distributions and Statistical Analysis

Jang, Kitae
Chan, Ching-Yao
2009

From a recent study of safety evaluation of HOV-equipped freeways, it was found that limited- access HOV lanes appear to have a safety performance disadvantage when measured by collision distribution or collision rates for the HOV lane alone and for the HOV and left lanes combined. This paper describes the work performed to verify the statistical significance of related findings. Several statistical tests were used: empirical cumulative density function (CDF), Kolmogorov-Smirnov Tests, and comparison of means based on Poisson Distributed Samples. The conclusion that continuous-access...

Influential Factors on Level of Injury in Pedestrian Crashes: Applications of Ordered Probit Model with Robust Standard Errors

Jang, Kitae
Park, Shin Hyoung
Chung, Sungbong
Song, Ki Han
2010

Pedestrian-involved crashes that occurred in the city of San Francisco over a six-year period, 2002–2007, were analyzed to examine various influential factors on the injury severity of pedestrian crashes. The crash data extracted from the Statewide Integrated Traffic Records System (SWITRS) include five categorical levels of injury severity in traffic crashes also in addition to detailed information about the features of each crash. This study applied an ordered probit model for injury severity analysis to specify the ordinal nature of injury categories. To draw unbiased implications...

Identification of High Collision Concentration Locations Under Wet Weather Conditions

Hwang, Taesung
Chung, Koohong
Ragland, David R.
Chan, Chin-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...

Effectiveness of a Commercially Available Automated Pedestrian Counting Device in Urban Environments: Comparison with Manual Counts

Greene-Roesel, Ryan
Diogenes, Mara Chagas
Ragland, David R.
Lindau, Luis Antonio
2008

High-quality continuous counts of pedestrian volume are necessary to evaluate the effects of pedestrian infrastructure investments and to improve pedestrian volume modeling. Automated pedestrian counting devices can meet the need for continuous counts of pedestrian volume and reduce the labor cost associated with manual pedestrian counting and data entry. However, most existing automated pedestrian devices are not well suited to the task of counting pedestrians in outdoor environments, and little is known about their effectiveness and accuracy. This study addresses the lack of...

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...

Health Impacts of the School Commute

Lee, Murray
Orenstein, Marla
Richardson, Maxwell J.
Ragland, David R.
2008

A dramatic decline in walking and cycling to school has been observed in many geographic and cultural regions, and most children in the US are now driven to school in private vehicles. There are a number of health implications associated with the choice of commute mode, including traffic safety, exposure to air pollution, and levels of physical activity and obesity, and the risks and benefits of each must be weighed. This paper reviews current evidence on these risks and benefits for each health topic area. From a traffic safety perspective, buses are best, while the risks of private...

Estimating Bicycle and Pedestrian Demand in San Diego

Jones, Michael
Buckland, Lauren
2008

This paper introduces the concepts behind estimating bicycle and pedestrian demand and provides an example of the development of a sketch-plan method for estimating bicycle and pedestrian demand from land use in San Diego County. The paper describes the methodology involved in collecting counts for the currently ongoing Seamless Travel project. The Seamless Travel project intends to develop a model for estimating bicycle and pedestrian demand within San Diego County. The project methodology includes conducting bicycle and pedestrian counts and intercept surveys over a two-year period...

Comparison of collisions on HOV facilities with limited and continuous access

Jang, Kitae
Chung, Koohong
Ragland, David R.
Chan, Ching-Yao
2008

This paper describes comparisons of traffic safety during the morning and afternoon peak hours in extended stretches of eight High Occupancy Vehicle (HOV) lanes with two different types of access – four corridors with continuous access and the others with limited access. Traffic collision patterns in two different types of HOV lanes were investigated by evaluating 1) the differences in collision distribution, severity, types of collisions and per lane traffic utilization, 2) spatial distribution of collision concentrations by using Continuous Risk Profile (CRP) approach, and 3)...