Evaluation of Skid Resistance of Road Marking Materials for Urban Streets

Road marking is one of the important traffic facilities which provide the guideline of traveling vehicles and passengers. On urban streets road marking also directs pedestrians a safe section for crossing the intersections. In most Asian countries, motor bikes occupy a great percentage of city trips. Road marking plays an even more important role of safety for the motor bike riders particularly when it is wet. This paper aims at studying the skid resistance of current road marking materials and researching the possible alternatives for improving the skid resistance of road marking. Studies are divided into two steps: experimental design and test on test section and field measurement of urban streets.
On the experimental section, four kinds of marking materials, self-adhesive tapes, regular paint, thermoplastics, and preformed thermoplastics, in combing with various percentages of glass beads and angular quartz materials are used, and the correspondent skid resistance values are measured by British Pendulum Tester, sand patch method, and Dynamic Friction Tester. Sixty-two specimen of twenty combinations, each has two to four repetitions, are tested in this study. From the results it is found that without any additive the preformed thermoplastics give the highest skid resistance value while the paint is the least one. The most commonly used road marking in Taiwan is thermoplastic material which does not meet the international standard of 45 BPN. However, thermoplastic materials with 20% pre-added glass beads by volume plus small percentage of angular quartz materials give the best results.
Moreover, 12 newly marked test sites are selected randomly from urban streets for skid resistance test. It is surprised to learn that none of them pass the 45 BPN when they are new, but the values increase with time gradually for the first four to five months and stay stable after that. The final readings are between 45 BPN to 60 BPN. In addition, this study also finds very high positive correlation between BPN and DFT no., but both of them have poor correlation to mean texture depth resulted from sand patch method.