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When reconstructing pedestrian impacts, it is important to identify the time to impact available. One of the assumptions when calculating the time to impact is the speed of the pedestrian. Although the majority of pedestrian collisions (including fatalities) occur midblock, most of the research conducted for pedestrian speeds is based on pedestrians travelling in a controlled environment (i.e. crosswalks, sidewalks, etc.). When a pedestrian is crossing midblock or “jay-walking,” there may be a sense of urgency for the pedestrian due to approaching vehicles. The sense of urgency is dependent upon the proximity of vehicles that are approaching, and/or the lane of the approaching vehicle with respect to the pedestrian. In this study, 304 pedestrian movements were analyzed, as they crossed midblock across traffic. Pedestrian speeds in relation to the accepted gap and the positioning of approaching vehicles were analyzed.

A primary goal of crash reconstruction (or collision avoidance system) is to determine whether a crash is avoidable or not. A prerequisite for the determination of avoidance is knowledge of the time that is available to a driver. In a path intrusion crash scenario, a method to determine the time available for a major road driver is to know the time a minor road driver accelerated before impact. This research is an attempt to model the time based upon acceleration distance. The current study involved two parts. Part one was a naturalistic study of driver acceleration behavior at two-way-stop controlled intersections. In part two, ten drivers with instrumented vehicles were asked to drive a route that included four acceleration runs at two-way-stop sign control intersections. In the naturalistic study, the accelerations were measured using video recordings and videogrammetry at known distances.