Data collection

The Effectiveness of Child Restraint Systems for Children Aged 3 Years or Younger During Motor Vehicle Collisions: 1996 to 2005

Rice, Thomas M.
Anderson, Craig L.
2009

Objectives. We estimated the effectiveness of child restraints in preventing death during motor vehicle collisions among children 3 years or younger.

Methods. We conducted a matched cohort study using Fatality Analysis Reporting System data from 1996 to 2005. We estimated death risk ratios using conditional Poisson regression, bootstrapping, multiple imputation, and a sensitivity analysis of misclassification bias. We examined possible effect modification by selected factors.

Results. The estimated death risk ratios comparing child safety seats with...

A Methodology for Counting Pedestrians at Intersections: Using Automated Counters to Extrapolate Weekly Volumes from Short Manual Counts

Schneider, Robert J.
Arnold, Lindsay S.
Ragland, David R.
2009

Accurate methods of counting pedestrians are needed to quantify exposure for safety analysis, rank infrastructure improvements and safety programs by priority, evaluate the benefits of pedestrian projects, develop models of pedestrian volumes, and track changes in pedestrian activity over time. However, pedestrian counts are still much less common than motor vehicle counts in most communities. In addition, existing count methodologies are not standardized and rarely provide enough information to extrapolate to weekly, monthly, or annual volumes. This exploratory study presents a...

Household Travel Surveys in Context-Based Approach for Adjusting ITE Trip Generation Rates in Urban Contexts

Clifton, Kelly J.
Currans, Kristina M.
Cutter, April C.
Schneider, Robert J.
2012

With household travel surveys (HTSs) to produce a regional-scale policy model, this research develops a methodology for predicting context-based vehicle-trip reductions applied to ITE’s Trip Generation Handbook at a site-level development. This methodology may be used as a supplement to ITE trip generation rates, providing justification to vehicle-trip reductions based on known contextual vehicle mode splits. With the 2006 HTS of the Puget Sound Regional Council, Washington State, non-home-based trip ends were selected, and common built environment measures were extracted. A clustering...

Pedestrian Crash Risk on Boundary Roadways University Campus Case Study

Schneider, Robert J.
Grembek, Offer
Braughton, Matthew
2013

Prominent pedestrian trip attractors, such as college campuses and major urban parks, are often surrounded by roadways with high volumes of motor vehicle traffic. Although many pedestrians cross busy boundary roadways, relatively little is known about the pedestrian crash risk along these types of facilities. This study quantifies pedestrian crash risk at roadway intersections on the boundary of the University of California, Berkeley, campus during typical spring and fall semester weekdays. Manual pedestrian counts were extrapolated with data from three automated counter locations to...

Developing Safety Management Tools for State Departments of Transportation

Chung, Koohong
Grembek, Offer
Lee, Jinwoo
Choi, Keechoo
2013

Two safety management tools have recently been developed for the California Department of Transportation (Caltrans). One is the continuous risk profile (CRP) approach, which is a network screening procedure, and the other is the California Safety Analyst (CASA), a web-based application designed to assist state safety engineers in conducting safety investigations and in documenting their findings. This paper provides a qualitative description of the two tools and summarizes feedback from more than 100 Caltrans safety engineers who attended demonstrations of the web-based application....

Drivers, Pedestrians, and Cyclists in California Want Complete Streets: Comparison of Results from Roadway Design Surveys of Pedestrians, Drivers, Bicyclists, and Transit Users in Northern and Southern California

Sanders, Rebecca L.
Griffin, Ashleigh
MacLeod, Kara E.
Cooper, Jill F.
2014

This paper compares findings from two recent surveys on roadway design preferences among pedestrians, drivers, bicyclists, and public transit users along major urban corridors in the metro areas of San Francisco and Los Angeles. Sponsored by the California Department of Transportation (DOT), the research explored design preferences that could increase perceived traffic safety, walkability, bikability, and economic vitality along urban arterials. Results from intercept surveys showed that roadway users desire similar design features along the test corridors, which carry 25,000-40,000...

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.
2012

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
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...

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.
2014

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...