Evaluation

The Effects of Transportation Corridors' Roadside Design Features on User Behavior and Safety, and Their Contributions to Health, Enviornmental Quality, and Community Economic Vitality: a Literature Review

Macdonald, Elizabeth
Sanders, Rebecca
Supawanich, Paul
2008

A transportation corridor communicates many things to its users through its design elements. What it communicates can affect the travel mode a user decides to take, the speed at which a motorist decides to drive, whether a pedestrian will walk along or across a street, and whether a resident will bicycle to local shops. Design elements give visual cues to the users of transportation corridors that let them know where they are and how to behave. The vehicle lane widths, presence or absence of sidewalks, and presence or absence of buffering elements such as street trees and parked cars all...

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.
2008

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...

Evaluation of Wet Weather Accident Causation Criteria

Oh, Soonmi
Ragland, David R.
Chan, Ching-Yao
2008

This report documents findings from analysis of traffic collision data from sites that display high collision rates only under wet pavement conditions. These sites were selected using Caltrans safety engineers’ field reports, Wet Table C “investigation required” locations, and a new approach called Continuous Risk Profile (CRP). The geometric features at the sites were studied via field visits and review of as-built plans. Rapid spatial changes (i.e., vertical and horizontal curve in short distance), narrower lane width, lack of median, and wider total freeway width were some of the...

Quantifying the Performance of Countermeasures for Collision Concentration Related to Ramp/Freeway Mainline Junctions

Lee, Joon Ho
Chan, Ching-Yao
Ragland, David R.
2009

This study performed before-and-after analyses (comparisons of collisions before and after the construction of auxiliary lanes) on collision rate at nine study sites in California in order to achieve two objectives: (i) to estimate the freeway Crash/Collision Reduction Factor (CRF) for auxiliary lanes, and (ii) to develop design guidelines for the construction of auxiliary lanes. Findings indicate that on average, collision rates decreased by 17.3 percent at nine study sites. The study also found that after construction of auxiliary lanes at two study sites, collision rates increased when...

Red-Light-Running Collision Avoidance

Grembek, Offer
Zhou, Kun
Zhang, Wei-Bin
2009

Red light running (RLR) problem has been recognized as a significant safety problem in California as well as throughout the United States. This paper follows a two step process to develop enhanced signal timing models for possible reduction of RLR. In the first step, field data are collected with one-second resolution and discrete choice models are estimated to determine the significant influencing factors of RLR; in the second step, based on the findings from the first step, T7F software package as well as custom designed programs is used to find the enhanced signal timing plans that can...

A Comparative Safety Study of Limited versus Continuous Access High Occupancy Vehicle (HOV) Facilities

Jang, Kitae
Ragland, David R.
Chan, Ching-Yao
2009
The report summarizes the findings from comparative studies of safety performance between two different types of High Occupancy Vehicle (HOV) facilities in California - continuous access versus limited access. The findings show that HOV facilities with limited access offer no safety advantages over those with continuous access, whether measured by percentage of collisions, collisions per mile, collisions per VMT, or collision severity. As part of the present research, the authors investigated the relationship...

Develop Methods to Reduce or Prevent Backing Crashes

Cooper, Douglas L.
Duffy, Sarah
Orrick, Phyllis
Ragland, David R.
2009

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...

Seamless Travel: Measuring Bicycle and Pedestrian Activity in San Diego County and its Relationship to Land Use, Transportation, Safety, and Facility Type

Jones, Michael G.
Ryan, Sherry
Donlon, Jennifer
Ledbetter, Lauren
Ragland, David R.
Arnold, Lindsay S.
2010

This paper provides the data collection and research results for the Seamless Travel project. The Seamless Travel Project is a research project funded by Caltrans and managed by the University of California Traffic Safety Center, with David Ragland, PhD., as the Principal Investigator and Michael Jones as the Project Manager. The project is funded by Caltrans Division of Innovation and Research and is being conducted by the Traffic Safety Center of University of California Berkeley and Alta Planning + Design. Measuring bicycle and pedestrian activity is a key element to achieving the goals...

Evaluation of Traffic and Environment Effects on Skid Resistance and Safety Performance of Rubberized Open-grade Asphalt Concrete

Oh, Soon Mi
Ragland, David R.
Chan, Ching-Yao
2010

Wet pavement-related collisions represent a significant traffic safety concern, due in part to the lack of adequate friction between tire and pavement, known as skid resistance. State agencies employ a skid number (SN) system, based on a standard test procedure in which a locked wheel is towed at 40 mph and the skid number (SN40) is calculated from the measured resistance. SN40 is used as a reference value for speeds both greater than and less than 40 mph. For most Departments of Transportation (DOTs) in the nation, excluding California, pavements for which the SN40 is below 30 are deemed...

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
2010

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...