This report provides a preliminary analysis of reduced visibility crashes to support the development of crash avoidance system (CAS) concepts as part of the Intelligent Vehicle Highway System (IVHS). In this report, a reduced visibility crash is defined and background on driver perception is presented in order to identify candidate sources of visibility limitations and enhancements. Some indications as to the size of the reduced visibility problem are presented. A detailed analysis of a sample of crashes is discussed to provide further insights into the nature of the problem. Candidate functional crash avoidance concepts are presented in terms of in-vehicle warning systems, roadway information systems, direct vision enhancement systems, and imaging vision enhancement systems. The mechanisms of reduced visibility and how it affects stopping sight distance are then presented together with recommended sight distances used in traffic engineering for highway safety. The analysis concludes with a list of research needs that will further an understanding of driver vision and perception requirements and the development of effective reduced visibility crash countermeasures. (Author/publisher)
Abstract