A programme of experiments is being undertaken by TRL for the Transport Research Foundation to determine whether detailed imaging of the road surface has potential to be applied to the determination of microtexture and hence to the measurement of skid resistance.
This report describes the most recent stage of research. It has been shown previously that it is possible to derive parameters from the images of stone surfaces which correlate well with friction measured on the surfaces. Whereas work to date has used aggregate samples manufactured in the laboratory and artificial polishing mechanisms, this new research has used images of real-road surfaces.
A new parameter is defined, CMT3, which is based on measurements of the variation in pixel intensities within images, and attempts are made to compare these image derived measurements with measurements of skid resistance. The work was carried out in two stages, firstly using images of cores taken from an experimental surface dressing site and secondly using images taken in-situ at various locations on the road network.
A good relationship is observed in the first stage, using images of cores, but the comparison is not as clear for images of the various road surfaces in the second stage, which may be due to the different textures of the latter surfaces and the differing ways in which the surfaces provide skid resistance. However, where longer continuous sections of road have been imaged, some clear similarities between skid resistance and CMT3 can be observed. Further fine-tuning of the image derived parameter is briefly attempted.
The work has shown that there are still limitations to this technique when a widely varying collection of surfaces are considered, but where it has been possible to make comparisons between continuous measurements of skid resistance, the method is very promising. It is suggested that future work should continue to utilise images of road surfaces in-situ and further investigate and strengthen the similarity between continuous measurements of skid resistance.

Want to know more about this project?