RATE OF WEAR OF EDGE MARKINGS ON ASPHALT AND SPRAYED SEAL

Results of a 68-week field trial for comparing the rate of wear of edge markings on asphalt to that on a sprayed seal are discussed. The trial was to validate the following two assumptions usually made when field assessments of the durability of road marking paints, are conducted: (1) Roadmarking paints wear out mainly because of the impact and friction of vehicular traffic; (2) The wearing characteristic does not depend on the road surface, and therefore the results obtained on asphalt are applicable also for other types of road surface, particularly a sprayed seal. In addition the effect of paint film thickness on the durability of edge markings was studied. The criterion for paint wear was the loss of drop-on glass beads which was determined by monitoring the retroreflectivity markings with a portable instrument. Although the number of vehicle passes on edge lines is negligible when compared to that on transverse lines, the degree of wear was unexpectedly high. The edge lines on a sprayed seal had worn much faster than those on asphalt. The results show that the two above assumptions, usually taken for granted, are not valid. Consequently, field trials to evaluate roadmarking paints, should also assess the durability of longitudinal linemarking and of markings on a sprayed seal. (a) For the covering entry of this conference, please see IRRD abstract no. 878228.