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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.

It is not surprising that many multi-vehicle collisions occur at intersections, as intersecting streets present potential conflict situations where vehicle paths can cross one another. What does surprise both naïve observers and many professionals involved in accident investigations (e.g., accident reconstructionists, human factors scientists, lawyers) is the explanation that most red light running accidents happen only when the vehicle violating the red light enters the intersection approximately 4 to 6 seconds or more after the light has turned red. This paper provides a framework to study the conditions under which red light running collisions occur. This framework is applied to real-world intersection geometries and red light running collisions captured on video. A comparison of observational and crash data indicates that only a small fraction of red light running results in collisions. The mathematical framework can be used to develop likely timing scenarios in accident investigation, and can be expanded to study motor vehicle collisions with bicyclists or pedestrians.

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.