Evaluation of Motorcyclists' and Bikers' Safety on Wet Pavement Markings

Abstract

In this study, three different pavement marking material types were evaluated by using a British Pendulum Tester (BPT) in dry, wet, and icy conditions. The frictional properties were recorded as a British Pendulum Number (BPN). Two different rubber sliders on the BPN were used to compare different pavement marking users: a pedestrian slip rubber (PSR) and tire slip rubber (TSR). This study included both laboratory and field testing. The pavement markings evaluated were chosen after a careful review of Washington State Department of Transportation’s specifications and Washington State University’s (WSU) Facilities Services common practices. During laboratory testing, a neat concrete slab surface was compared to waterborne paint, preformed fused thermoplastic, and cold applied pre-formed tape surfaces. Each of the surface types was evaluated under dry, wet, and icy conditions. Laboratory test results showed that the paint and thermoplastics resulted in lower BPN values than the neat concrete surface. However, the centerline striping that was tested did show higher frictional properties than the neat concrete surface because of the contours and surface macrotexture of the tested striping. During field testing, two locations on the WSU Pullman campus were chosen for testing in dry and wet conditions. Each location was evaluated by using the BPT, and then two bicyclists rode over the markings in a variety of ways in dry and wet conditions. The tested locations were painted markings. A safety scale was created for riders to evaluate the field markings. The results showed that riders generally felt safe while riding in a straight line over the pavement markings. Most of the unsafe ratings occurred during wet testing, and as cyclists turned and braked over the pavement markings. In comparing the laboratory and field testing BPN values, the laboratory values were typically higher. This was most likely due to the fact that beads were present on the laboratory markings and not on the field markings. From these results, the authors concluded that centerline striping showed the most promising frictional properties. Although paint and thermoplastics showed lower frictional properties than those of the neat concrete surface, the use of beads helped improve the laboratory values over the field testing values.