Delphine Cody

Cooperative Collision Warning Systems: Concept Definition and Experimental Implementation

The concept of cooperative collision warning (CCW) systems is introduced and explained, followed by presentation of experimental results showing the performance of a first prototype CCW system. The CCW concept provides warnings or situation awareness displays to drivers based on information about the motions of neighboring vehicles obtained by wireless communications from those vehicles, without use of any ranging sensors. This has the advantages of a potentially inexpensive complement of onboard vehicle equipment (compared to ranging sensors that could provide 360-degree coverage), as well as providing information from vehicles that may be occluded from direct line of sight to the approaching vehicle. The CCW concept has been tested on a fleet of five prototype vehicles, supporting a variety of safety services (forward collision warning, blind spot and lane change situation awareness, and several modes of intersection threat assessment). The performance of the vehicle position estimation and wireless communication subsystems are demonstrated using samples of experimental data from test sites with both good and bad Global Positioning System (GPS) signal availability.

Comparison of Infrastructure and In-Vehicle Driver Interfaces for Left-Turn Warnings

To examine the feasibility of driver–infrastructure interface (DII) and driver–vehicle interface (DVI) in the context of a left-turn assistance system, 20 test participants drove through a test-track intersection with oncoming traffic. Participants decided, both with and without the aid of a real-time warning, whether there was enough time to turn in front of oncoming traffic. This study examined both the effects of warning location (DII versus DVI) and the timeliness of the warning onset, while controlling for vehicle arrivals to the intersection as measured by an algorithm that predicted the spare time (trailing buffer) if the participant decided to turn in front of an oncoming vehicle. Lag (gap) acceptance increased as the predicted trailing buffer increased, with almost all lags with a predicted spare time greater than 1 s accepted and almost all lags with a predicted spare time fewer than −1.5 s rejected. The presence of warnings in either location resulted in a reduction in the turning rate, but there were no differences between warning locations. Most drivers preferred the DII in this instance, but based on participants’ feedback, a visual-only DVI located more central to the drivers focus of attention may also be acceptable. In regard to warning onset, information provided as decision support, rather than a preemptive or reactive warning, will likely need to be provided about 3.5 to 4.5 s before a driver reaches the intersection, to be integrated into the drivers decision process.

TRB Workshop on Driver Models: A Step Towards a Comprehensive Model of Driving?

Various disciplines use the same or similar terminology for driver models — vehicle and traffic engineering, psychology, human factors, artificial intelligence to mention the most common; however, the definition of the term varies not only between disciplines but even between different researchers within any given discipline. Recent efforts in applied psychology and human factors have emphasised the need of developing models that can be implemented and used in computer simulation, hence representing a possible link between these disciplines, and also a chance to consider the broader picture of driver model within a transportation/traffic system. In order to discuss this link, the authors organised a workshop on driver modelling during the 84th annual meeting of the Transportation Research Board, Washington, DC. The workshop was attended by 25 researchers from the various fields listed above and lead researchers from the United States, Europe and Asia.

Site-Based Video System Design and Development

The goal of the Strategic Highway Research Program 2 (SHRP 2) Safety program is to prevent or reduce the severity of highway crashes through more accurate knowledge of driver behavior and other factors. The Safety program’s research is proceeding along two distinct but related tracks: (1) the in-vehicle, naturalistic driving study, which encompasses all types of driving, and (2) the site-based risk study, which focuses on vehicle trajectories at specific locations, such as intersections. This report describes the work that was done in the latter track to develop and test an on-site, video-based data collection system with the potential for widespread application by researchers and state and local authorities to examine intersection safety. This report documents the development of a prototype system capable of capturing vehicle movements through intersections by using a site-based video imaging system. By tracking individual vehicles through an intersection, the Site Observer provides a basis not only for viewing crashes and near crashes but also for developing objective measures of intersection conflicts and collecting before-and-after data when design or operational changes are made at intersections. It also yields detailed and searchable data on the normal driving population so that exposure measures can be determined. This research built on previous work on video-based systems to develop a system that is relatively inexpensive, portable, and flexible enough for installation at all types of intersections, as well as robust enough for use in locations with a wide range of environmental conditions. The system embraces modern machine vision cameras and draws from the large body of research on algorithms for extracting information from video streams, a key advantage where data must be collected continuously. It was tested at a location during fall and winter months and found to operate as designed. The Site Observer is a robust prototype system that is deployable as is but is also capable of further development and refinement for use in intersection safety assessment.