Most of the information that drivers require is acquired through their eyes. Therefore, for safe high-speed driving, it is important to obtain accurate visual information about the road and its geometric features. There are, however, some cases in which the visual information is perceived incorrectly by drivers and this is one cause of accidents when complicated alignments are used. Two experiments have been conducted to determine which combinations of horizontal and/or vertical alignments would cause such visual illusions to be experienced on expressways. First, expressway patrol drivers who drive every day over a certain section of an expressway were questioned to determine if they experienced such illusions while they were driving there. Secondly, several ordinary drivers were asked to report everything that they saw while they were driving the same sections of the expressway. The drivers were being recorded continuously by a video camera. Analyzing the relationships between the locations and illusions, and the combinations of horizontal and/or vertical alignments, a few facts were derived in regard to alignments and a certain type of illusion. An attempt was also made to determine the relationship between the occurrence of visual illusions and traffic accidents by surveying traffic accident records. However, it does not seem that there is any significant correlation between the occurrence of illusions and the type and the likelihood of traffic accidents.
Samenvatting