Data collection

Observational Survey of Cell Phone Use and Texting by California Drivers, 2011

Cooper, Jill F.
Ragland, David R.
Ewald, Katrin
Wasserman, Lisa
Murphy, Christopher J.

This methodological report describes survey research and data collection methods employed for the first observational survey of cell phone use and texting by California drivers. This study was conducted by Ewald and Wasserman Research Consultants on behalf of the California Office of Traffic Safety and the Safe Transportation Research and Education Center at the University of California, Berkeley. The goal of the survey was to obtain a statewide, statistically representative observational sample. Vehicle drivers were observed at controlled intersections, such as traffic lights and stop...

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

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.

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...

Investigating Bicyclists' Perception of Comfort on Physically Separated Bicycle Paths in Nanjing, China

Li, Zhibin
Wang, Wei
Liu, Pan
Schneider, Robert J.
Ragland, David R.

Providing bicyclists favorable and comfortable riding environments is an important objective for transportation professionals. This study investigated the factors that contribute to bicyclists' perception of comfort on physically separated bicycle paths and quantified their impacts. A survey was conducted on 29 physically separated bicycle paths in the metropolitan area of Nanjing, China. A factor analysis and an ordered probit model were used to analyze the data. The results showed that the mean perception of comfort was significantly different between age groups, but not...

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

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

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...

Visual Assessment of Pedestrian Crashes

Griswold, Julia B.
Fishbain, Barak
Washington, Simon
Ragland, David R.

Of the numerous factors that play a role in fatal pedestrian collisions, the time of day, day of the week, and time of year can be significant determinants. More than 60% of all pedestrian collisions in 2007 occurred at night, despite the presumed decrease in both pedestrian and automobile exposure during the night. Although this trend is partially explained by factors such as fatigue and alcohol consumption, prior analysis of the Fatality Analysis Reporting System database suggests that pedestrian fatalities increase as light decreases after controlling for other factors.


Develop Methods to Reduce or Prevent Backing Crashes

Cooper, Douglas L.
Duffy, Sarah
Orrick, Phyllis
Ragland, David R.

Workplace motor vehicle incidents at Caltrans are a significant cause of injuries, employee lost time, and property damage. Because backing crashes are major contributors to motor vehicle incidents, identifying and promoting methods of reducing backing accidents is a top priority. According to internal Caltrans’ data, 92.3% of workplace backing crashes were preventable by the driver. Backing crashes are the single largest category of preventable crashes, representing 30% of preventable crashes in the Caltrans fleet. From 1998 through 2007, preventable backing crashes cost Caltrans at least...

Evaluate the Causes of Pedestrian and Bicyclist Traffic Fatalities and Injuries, and Establish Appropriate Countermeasures for Use in California

Arnold, Lindsay S.
Ragland, David R.
Yip, Harry
Cooper, Doug
MacLeod, Kara E.
Hennessey, Daniel
Mitman, Meghan F.
DuBose, Brooke

The three primary objectives of this project were to: (1) conduct research on existing bicycle and pedestrian safety programs and guidelines in the U.S. and internationally, (2) obtain and analyze existing data related to pedestrian and bicycle safety in California, and (3) assist in developing methodologies for producing safety action plans, identifying and selecting projects, conducting education campaigns, and targeting enforcement campaigns. To meet these objectives, SafeTREC developed a set of resources and tools for use in California. These resources make information and data on...

Methods for Identifying High Collision Concentration Locations for Potential Safety Improvements

Geyer, Judy
Lankina, Elena
Chan, Ching-Yao
Ragland, David R.
Pham, Trinh
Sharafsaleh, Mohammad A.

The California Department of Transportation (Caltrans) uses Table C and related documents to identify and to investigate locations within the state highway system where a relatively large number of collisions occur. In earlier years, a task force evaluated the process of generating and using these reports and found that there was much room for improvements. A list of recommendations was made. The efforts undertaken within this project is part of the effort to make the process of safety investigations and improvements more efficient and productive. This report summarizes the work carried...

Qualitative Comparison of North-American Procedures for Areawide Pedestrian Travel Measurement

Greene-Roesel, Ryan
Diógenes, Mara C.
Ragland, David R.
Lindau, Luis A.

There is no standard system for estimating area-wide pedestrian volumes in the United States. As a result, pedestrian volumes cannot be routinely used to guide transportation investments and monitoring measures performance. Vehicle volumes, by contrast, are measured systematically in each state and are reported to the Federal Highway Administration annually to be used in the allocation of federal funds. This paper investigates the advantages and disadvantages of three approaches to the creation of a standard system of pedestrian volume measurement: direct sampling, survey methods, and...