Often as part of accident reconstruction the question of visibility arises. Examples range from a simple daytime obstruction to the more complex case of nighttime human perception. With these cases, it is often necessary to analyze the visibility aspects of the accident situation and determine if a reasonably alert person would have been able to detect certain objects associated with the accident. In order to analyze the accident situation, a method for studying various visibility aspects is needed.The purpose of this paper is to present a methodology to study visibility aspects of an accident. It will present field reconstructions of both daytime and nighttime accidents, and unique examples illustrating target detection factors and how they can lead to an increase in visibility at night. The methodologies will include still photography, video and motion pictures. While daytime visibility studies will be addressed, the main portion of this paper will concentrate on the nighttime visibility studies.