Pavement markings were placed ahead of a high-accident location (a sharp curve). Speed and accident studies were conducted before and after. The markings were placed so that drivers otherwise failing to reduce speed would see the markings at an increasing rate. The spacing of lines was intended to create an illusion of acceleration which would cause the driver to slow. Speed is perceived by the visual senses; drivers sense forces resulting from changes in speed but relate and associate speed to the visual field. In laboratory experiments, it has been shown that a driver's perception of speed can be varied by introducing structured patterns onto the road surface (1). Field tests have resulted in varying degrees of success (2, 3). However, it has been found that improper approach to a curve is related to perceptual assessment problems (4). Several site comparisons between uniform and illusionary marking patterns would have to be evaluated to conclusively demonstrate any illusionary effects. The idea of compressed spacing, therefore, remains somewhat intuitive. The objective of this study was to determine if these markings would affect speeds and accidents at a field installation.

Report Date


Report Number

No. 539

Digital Object Identifier



Offered for publication by the Transportation Research Board.