Noticeability requirements for delineation on nonilluminated highways

At night, on non illuminated highways, delineation consisting of surface markings, raised pavement markers, post mounted delineators, and warning signs is especially important in providing path guidance information to motorists. The visibility of these delineation elements depends upon the extent to which headlight illumination is reflected back to the motorist by both the delineation and the roadway surface against which it is seen. The driver's capacity to receive and use this visual information depends on the specific highway situation, which is defined by the combination of road geometry, traffic operations, glare from opposing vehicles, road surface conditions, and the visual complexity of the background. This research project investigated how those aspects of the driving environment interact and affect the need for delineation types and reflectivity to satisfy the motorist's need for path guidance information.