No abstract

Unobtrusive observations of bicyclists were conducted at two-way, three-way, and four-way stop-controlled intersections. Consistent with previous reports, most cyclists did not stop at the stop sign.However, most cyclists did exhibit safety-related behaviors by making accommodations for traffic conditions. It was found that the cyclists conducted precautionary visual search when approaching stop signs, and that they were more likely to slow substantially or stop if cross traffic was not controlled by stop signs or if there were potential conflicts from other road users. Implications for safety interventions are discussed.

Vehicle codes require that a driver entering an intersection should yield right-of-way if an approaching vehicle is close enough to be an immediate hazard. This paper discusses a framework for contributions from human factors and vehicle kinematics to right-of-way questions, based on defining immediate hazard as a situation requiring an aggressive avoidance maneuver. A variety of issues that arise can be addressed with existing technical literature, while others suggest a role for further empirical research. Quantitative analyses reveal the relative importance of factors such as distance perception, response latency and initial speed.

When the sun is low in the sky, a driver headed directly towards the sun is subject to glare, which impairs target detection. Unobtrusive (video) observations of drivers approaching a setting afternoon sun found only a small decrease in speed compared with a non-glare condition; in addition, speed variability appeared to increase somewhat in the sun condition. These effects, which are similar to what has been reported for driver behavior in fog and other impaired-visibility conditions, increase the risk of accidents. Causes and implications are discussed in the paper.

When faced with a potential hazard, a pedestrian may need to change course, stop, maintain speed or accelerate. Logically, this must involve both a delay phase (to perceive a hazard and formulate a response) and an action phase (e.g., to arrest forward momentum in a stopping response). Qualitatively, the decision and response processes are similar to those an individual faces while driving an automobile or riding a bicycle, but very little research has been found on this subject for pedestrians. In the current study, jogging or walking subjects were asked to stop quickly in response to an auditory signal, and data were extracted from video recordings of the trials. The reaction time phase observed in the study was similar to prepared reaction times in other settings. The halting phase visibly began with a change in body angle, with rapid deceleration following the subsequent heel strike. Both the time and the distance to stop required from a jog or walk can be important for analysis of vehicle-pedestrian collisions and other mishaps.