Evaluation

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...

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...

Applying Safety Treatments To Rail-Highway At-Grade Crossings

Cooper, Douglas L.
Ragland, David R.
2012

At-grade rail crossings provide different levels of warnings and/or barriers to alert drivers to the potential dangers presented by approaching trains. For some drivers, an activated warning system, rather than being a signal to stop, merely serves as a cue for the need to make a decision whether or not to cross. In California, for the ten-year period from 2001 to 2010, the result was 1,033 trainvehicle crashes resulting in 157 deaths and 458 injuries. The best solution to rail crossing crashes is to remove the need for the driver to engage in a potentially faulty decision-making process...

Modeling Bicycle Passing Maneuvers on Multilane Separated Bicycle Paths

Li, Zhibin
Wang, Wei
Liu, Pan
Bigham, John M.
Ragland, David R.
2012

Bicycle passing maneuvers represent interferences between bicycle travelers and are important operational attributes of bicycle traffic. The number of bicycle passing maneuvers has been used to evaluate the level of service (LOS) of off-street bicycle facilities. The primary objectives of this paper are to propose a method to model bicycle passing maneuvers on multilane bicycle paths with heavy bicycle traffic and explore the characteristics of those passes. The authors classified bicycle passing maneuvers into free, adjacent, and delayed passes according to the lateral distance...

Variations in Teens' Perception of Risk Factors for Teen Motor Vehicle Collision Injuries

Chen, Katherine L.
Cooper, Jill F.
Grembek, Offer
Henk, Russell
Tisdale, Stacey M.
2014

Teen drivers, especially males, are known to be at greater risk of being involved in a motor vehicle collision than any other age group. While novice teen drivers’ primary risk factors are commonly known, less is known about what teens perceive as risk factors for peers getting hurt or killed in motor vehicle collisions. This mixed methods study uses survey data from the Teens in the Drivers Seat (TDS) program in California to explore (1) teens' perceived risk factors for motor vehicle collision injury; and (2) the relationship between perceived risks and age, gender, and driving...

Predictors of Nonstandard Helmet Use Among San Francisco Bay–Area Motorcyclists

Tsui, Casey K.
Rice, Thomas M.
Pande, Swati
2013
Objective: The use of helmets that do not comply with safety standards is common in California. The objective of this study was to describe the use of these nonstandard helmets among San Francisco Bay–area (SFBA) motorcyclists and to identify personal and motorcycle characteristics that are associated with the use of nonstandard helmets. Methods: A survey of 860 SFBA motorcyclists was conducted. Log-binomial regression was used to estimate risk ratios to compare probabilities of nonstandard helmet use. Results: Fifteen percent of motorcyclists reported wearing a nonstandard helmet sometimes...

Estimating Pedestrian Accident Exposure: Automated Pedestrian Counting Devices Report

Bu, Fanping
Greene-Roesel, Ryan
Diogenes, Mara Chagas
Ragland, David R.
2007

Automated methods are commonly used to count motorized vehicles, but are not frequently used to count pedestrians. This is because the automated technologies available to count pedestrians are not very developed, and their effectiveness has not been widely researched. Moreover, most automated methods are used primarily for the purpose of detecting, rather than counting, pedestrians (Dharmaraju et al., 2001; Noyce and Dharmaraju, 2002; Noyce et al., 2006). Automated pedestrian counting technologies are attractive because they have the potential to reduce the labor costs associated with...

Estimating Pedestrian Accident Exposure: Protocol Report

Greene-Roesel, Ryan
Diogenes, Mara Chagas
Ragland, David R.
2007

Walking is a healthful, environmentally benign form of travel, and is the most basic form of human mobility. Walking trips account for more than 8 percent of all trips taken in California, making walking the second most commonly used mode of travel after the personal automobile (Caltrans, 2002). In addition, many trips made by vehicle or public transit begin and end with walking.

In spite of the importance and benefits of walking, pedestrians suffer a disproportionate share of the harm of traffic incidents in California. As noted above...

Integration of Light Rail Transit into City Streets

Korve, Hans W.
Farran, Jose I.
Mansel, Douglas M.
Levinson, Herbert S.
Chira-Chavala, T.
Ragland, David R.
1996

This report addresses the safety and operating experience of light rail transit (LRT) systems operating in shared (on-street or mall) rights-of-way at speeds that do not exceed 35 mph. It is based on agency interviews, field observations, and accident analyses of 10 LRT systems in the United States and Canada. These systems—in Baltimore, Boston, Buffalo, Calgary, Los Angeles, Portland, Sacramento, San Diego, San Francisco, and San Jose—provide a broad range of current LRT operating practices and problems.

The report provides information to facilitate the safe, orderly, and...