A complete analysis of any vehicular collision needs to consider certain aspects of human factors. However, this is especially true of nighttime collisions, in which a more specialized approach is required. Classical collision investigation (frequently referred to as accident reconstruction) is comprised of kinetic and kinematic considerations including skid analysis, momentum techniques and other methods. While analysis based on these concepts is typically unaffected by low visibility conditions, the opposite is true of the perceptual and cognitive aspects of a “humans-in-the-loop” analysis, which can be enormously impacted by low visibility. Only by applying appropriate human factors techniques can the analyst make a defensible determination of how and why a nighttime collision occurred. Topics of special importance for nighttime analysis include perception-reaction time (PRT), sensation, attention, distraction, and expectation, all of which are strongly influenced by limited levels of lighting. These considerations often help to explain the behavior and response of both pedestrians and drivers involved in nighttime collisions.
The primary goal of this paper is to explore appropriate usage of common human factors concepts during nighttime situations, and to incorporate additional techniques (such as headlamp illumination maps and validated photography) that are especially useful when analyzing nighttime scenarios. A realistic example is presented in which specialized techniques are used in conjunction with classical analysis techniques. It is the combination of classical collision analysis and the application of a specialized human factors approach that enables a more complete comprehension of the cause of nighttime vehicular collisions.