This report is the final report of working group e 9 "visibility of road markings on wet road surfaces" of the dutch research centre for road construction (scw) and the dutch research centre for traffic engineering (svt). It presents the results of a research programme that can be considered as the follow-up of the investigation executed in 1981 and 1982 concerning the wet night time visibility of a number of delineation materials. The latter clearly indicated that in the long run the visibility of road markings mainly depends on the material properties as well as on the geometry in which the materials are applied. Previous research had indicated that road markings are most effective at a minimum lateral distance and a maximum vertical distance from the eyes of the road user. An attempt to investigate in what combination optimum effect is achieved was made in the present geometric research. A better understanding has been gained by observing the viewing and driving behaviour of the members of a panel who were instructed to drive at a prescribed speed of 80 km/h over road sections with pre-selected marking geometries. Both straight sections and sections with radii of 1000 and 200 m were included. The markings had been applied as line, at mutual intervals of 3 and 9 m and at intervals of 12, 24 and 36 m. The set-up of the test had been selected for both the intervals as such, and for combinations of different guidance aids. When dealing with the material properties distinction was made between vertical profiled thermoplastic markings and retroreflective raised road markers. In total, nine vertical profiled markings and eleven retroreflective road markers were investigated. The tests referred to the visibility properties both by day and at night. The conclusions were based on the measuring results up to two years after construction: they gave a proper indication of the property behaviour during the full extent of the material lifetimes. The research programme, however, covers a period of five years. For at least this period the materials will have to be exposed to the effects of traffic and climate to allow researchers to pronounce upon lifetimes of a minimum of six and a maximum of twelve years. The test sections were built at the end of 1982, so that the results of a five-year period are not available yet. This report also gives the results of the noise effects that occur when the road markings are being driven over. With regard to the nuisance of continuous noise and that of intermittent noises a remarkable difference had appeared. This publication is concluded by an indicative picture of the cost aspects of various road marking types, and by a survey of developments in other countries, on the basis of an additional literature research. (author/publisher)
Samenvatting