Statistical Assessment of the Glare Issue - Human and Natural Elements

Visibility is one of the basic requirements for safe driving; any type of obscurity in a driver’s vision can interfere with the driving task and impose a threat to the roadway safety. Glare is known to be one of the significant factors causing vision obstruction. One would agree that headlamps are not the only source of glare. Sometimes, sunlight may also obstruct a driver’s vision and contributing to a crash. In this paper, the glare issue and some of its aspects are studied using statistical methods. Crash data are used in the analyses. Descriptive statistical and contingency analyses are employed with the objective of a preliminary investigation. The k-nearest neighbor approach is used to assess the potential of some factors in jointly contributing to the crash involvement of drivers who are exposed to glare. Configural frequency analysis is used for identifying the data segments in which glare, as a crashcontributing factor, is more predominant. Some results based on drivers’ perceptions of glare, reported in a prior study, are discussed to compare perception with reality, i.e., how drivers perceive glare and how in real life their driving ability is affected by glare.