Motorized Vehicle Safety

Impact of Pedestrian Presence on Movement of Left-Turning Vehicles: Method, Preliminary Results & Possible Use in Intersection Decision Support

Banerjee, Ipsita
Shladover, Steven E.
Misener, James A.
Chan, Ching-Yao
Ragland, David R.

Warning systems are being developed for left-turning vehicles at intersections where protected left-turns are not warranted or cannot be provided, based on limitations of right of way or intersection capacity. These are meant to provide warnings to left-turning vehicles of vehicles approaching from the opposite direction, when the time to turn may be deemed unsafe. To implement these warning systems, it is necessary to estimate in near real time, the probability of conflict between the two approaching vehicles. A study is being conducted with the help of video and radar at various...

Rural Road Links: A Review on Current Research Projects & Initiatives Aimed at Reducing Vehicle Crash Fatalities on Rural Roads

Quiros, Lesliam
Shaver, Barrett

Rural America accounts for a smaller and more dispersed portion of the nation’s population, yet it comprises a considerable portion of the transportation system. Rural areas account for approximately 83 percent of the land in the U.S and their roads account for 80 percent of the total U.S. road mileage and 40 percent of the vehicle miles traveled. Fatalities on rural roads surpass those in urban areas, even though urban areas are more densely populated and consequently, have a higher traffic flow. In 2001 alone, fatal crashes on rural areas accounted for 61 percent of all traffic...

Intersection Decision Support Project: Taxonomy of Crossing-Path Crashes at Intersections Using GES 2000 Data

Ragland, David R.
Zabyshny, Aleksandr

The Intersection Decision Support (IDS) Project is designed to reduce crossing-path (CP) crashes at intersections by providing crucial information to drivers that would help them avoid such crashes. Over the past decade, researchers have used the General Estimates System (GES, a representative sample of police-reported crashes in the US) and other data sources to develop a taxonomy of CP crashes and pre-crash scenarios as groundwork for crash-prevention efforts. The current study builds on and extends prior work by constructing a taxonomy of CP crashes using data from the 2000 GES and...

Safety and Other Impacts of Vehicle Impound Enforcement

Cooper, Douglas L.
Chira-Chavala, T.
Gillen, David

This study was conducted by a team of researchers at the Institute of Transportation Studies, University of California at Berkeley, with funding from the California Office of Traffic Safety. Ted Chira-Chavala directed the study, coordinated the write-up of the final report, and wrote many chapters. Douglas Cooper was the key researcher, who performed the literature review, worked with key personnel of Upland Police Department to acquire essential data for the evaluation, analyzed the data, and contributed significantly to all chapters. David Gillen performed all time-series analyses and...

Driver/Pedestrian Understanding and Behavior at Marked and Unmarked Crosswalks

Mitman, Meghan F.
Ragland, David R.

Pedestrian injuries at crosswalk locations represent a significant problem. In 2002, 22.7 percent of US pedestrians involved in collisions were in a crosswalk at the time of the collision, and over 96% of these occurred at an intersection. Almost all crosswalk collisions resulted in pedestrian injury or fatality (98.6 percent), and about one-third resulted in severe or fatal injury (National Automotive Sampling System (NASS) and General Estimates System (GES) 2002). As the owner of the California State Highway System, Caltrans is responsible for providing access to safe and...

Applying Safety Treatments To Rail-Highway At-Grade Crossings

Cooper, Douglas L.
Ragland, David R.

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...

Building a Highway Linear Referencing System from Preexisting Reference Marker Measurements for Transportation Data Management

Bigham, John M.
Kang, Sanghyeok

To manage events associated with highways, data systems have been developed to store relevant event information. To reap the full benefits of geographic information system technologies, the relative locations can be integrated into a linear referencing system. The objective of this paper is to present a methodology for building a highway linear referencing system by applying preexisting marker measurements to a digital street network. The system was developed for locating motor vehicle collisions in California and resulted in improved accuracy compared to a previously developed...

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.

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...

Error Consideration for Geocoding Police Reported Collision Data in California

Bigham, John M.
Oum, Sang Hyouk

Geographic Information Systems (GIS) are frequently used to analyze collision data. In order to 3 utilize GIS, the data must be geocoded, or assigned a latitude and longitude coordinate by 4 translating a descriptive location onto street network data. However, the ability for accurate 5 spatial analysis can be limited by geocoding errors that may occur due to limitations in data 6 collection technologies, incorrect data entry due to human error, or inaccurate street reference 7 data. In the state of California there is an increased opportunity for data entry errors, given the 8 long...

Using Variable Speed Limits To Reduce Rear-End Collision Risks Near Recurrent Bottlenecks

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

Rear-end collisions would occur if vehicle speeds decrease abruptly when encountering kinematic waves (KWs) emanating from active bottlenecks. This study aims to develop a control strategy in variable speed limits (VSL) to reduce rear-end collision risks near recurrent bottlenecks. Using the crash prediction model developed for rear-end collisions related to risky KWs, the effectiveness of VSL control strategies were evaluated in the cell transmission model (CTM). Several strategies were tested in sequence to determine the best case for risk reduction. Results of this study show that the...