The focus of this research project was to identify suitable continuous measuring methods for the continuous evaluation of the skid resistance of road markings and derive possible connections between these continuous methods and the results of the skid-resistance-tester (called: SRT, measurement unit: British-Pendelum-Number "BPN"). This was to develop the bases for a continuous measurement of the skid resistance of road markings, particularly in view of the increasing tendering of building projects in the form of functional building contracts or public/private projects. To this effect on the basis of literature research three continuous skid resistance measuring systems were included in the tests - the ViaFriction, the GripTester and the SKM measuring system. In order to derive reference values with the standard evaluation method, three different marking materials (paint, cold plastic and foil) with different levels of skid resistance were applied to a test stretch and subsequently evaluated with regard to skid resistance using the continuous measuring systems and the surface friction tester. A skid resistance range of 35 to 75 BPN could be realised. The starting point for the investigations consisted of pre-tests which defined the necessary boundary conditions for a continuous evaluation of the skid resistance of road markings and formed the basis for the subsequent main tests. Here the influence of the marking width, the measuring speed and the type of marking (continuous or broken) was observed on the so-called "detection rating", i.e. the quality of the marking crossing of the continuous methods ViaFriction and GripTester. In agreement with the contracting authority it was decided not to use the SKM measurement vehicle in the pre-tests. The results of the pre-tests showed that with regard to both the ViaFriction and the GripTester the quality of the measurements is influenced by the same factors. Accordingly it became apparent that the detection quality of the measurements depends on the width of the markings. A dependence on the measurement speed could not be established in the pre-tests. This could however be established in further tests on a longer test stretch in the course of the subsequent main experiments. Furthermore it became apparent that valid measurements on broken road markings, taking into account the necessary transition areas at the transition between the road surface and the road markings and the recording frequency of the measurement methods, could not be realised or only at a reduced measuring speed. In the course of the main experiments, based on the reference tests with the SRT and the three continuous measurement methods (ViaFriction, GripTester and SKM), comparative values could be derived for the adherence to the minimum skid resistance of 45 BPN according to ZTV M 02 and 50 BPN as a "transfer value" according to the discussion paper "Guidelines on functional requirements of road markings" [FASA 2010/June; 2010]. This forms the basis for a "within the flow" evaluation of the skid resistance of road markings under traffic. In addition for each continuous measurement method and for each speed "?-confidence areas", "?-fuzzy areas" and "?-rejection areas" were defined taking into account the measurement errors of the methods. This would make it possible to reduce the amount of necessary SRT-measurements for the evaluation of the skid resistance condition of road markings to a minimum in the future. Only in the "?-fuzzy area" should additional SRT-measurements be carried out in order to make the statements of the continuous measurements more precise. In the confidence or rejection areas however such additional measurements are not necessary. To summarise the results of the present investigation, the continuous measurement systems included in the tests basically proved to be suitable for the continuous measurement of the skid resistance of road markings. However, it is recommended at the present moment not to use solely the continuous evaluation of the skid resistance of road markings in practice, but to use it in addition to the skid-resistance-tester. It is also recommended to first enlarge the basic database by observing further marking materials and additional skid resistance levels. In view of the increasing use of structure markings and agglomerates the skid resistance evaluation of such road markings with continuous measurement methods also seems to make sense. (Author/publisher)
Samenvatting