Effects of Road Marking Visibility on Vehicles Driving Along Curves: A Preliminary Study in a Simulated Environment

The role of road markings is fundamental for traffic safety, as it represents an essential optical driving instrument both for effective drivers and autonomous vehicles. This research aims to evaluate the effects of the decay of road marking visibility along curves, specifically the variability in lateral acceleration. Traditionally, issues related to the correct interpretation of a road alignment were studied by means of trajectory analyses. However, they involved information about the vehicle's geometrical position without any indication on dynamics. To explore this aspect further, an experiment in a simulated environment involving 21 drivers was performed. They drove along a test road in a standardized scenario considering only three variables: the curve direction (right or left), the deviation angle (70 degrees or 30 degrees), and the road marking visibility percentage (100%, 50%, 10%, and 0%). The results, in differences between theoretical (depending on design speed and curve radius) and effective lateral accelerations, provide further evidence of the strategic role of the markings. However, when markings deteriorate, drivers activate some balancing mechanisms to mitigate the dynamic effects along curves and, in turn, to improve comfort and safety. The proposed procedure is not only of direct practical interest, but it is also fully generalizable to other contexts and issues, involving several other elements that may influence the phenomenon, such as road geometry, visibility conditions, and traffic flow speed.