Trials of high-friction surfaces for highways

With the increasing number of systems available which provide high-friction surfaces, the 'recipe/method' specifications based on the original bitumen-extended epoxy-resin system have become inadequate. Therefore, a series of road trials in various parts of England, mostly on approaches to roundabouts, have been set up to compare the performance of three alternative resin systems with those of epoxy-resin systems. The trials were laid between 1991 and 1993, giving between four and six years of in-service performance. From the results, the overall ranking order of resins trialled that is beginning to emerge is the epoxy-resin system first, then the polyurethane-resin system, followed by the acrylic-resin system just ahead of the rosin-ester system. Laboratory tests have been devised to simulate accelerated wear under trafficking and a limited programme has been carried out which appears to give a similar ranking. The results have been used to develop performance-related criteria for a Highway Authorities Product Approved Scheme (HAPAS) certification procedure which can be used to assess existing systems and systems that may be developed in future. (A)