Evaluating Skidding Risk of a Road Layout for All Types of Vehicles

This paper represents an updating of research previously begun by the authors concerning a new method to analyze the problem of friction of road vehicles. Starting from the 3rd criterion of Lamm, the new concept of “Friction Capital” was introduced in previous work, as the limit performance of the road in terms of friction. This method has been named Friction Diagram Method; its output is the Friction Diagram that represents the percentage of “Friction Capital” that a vehicle is using traveling on a given road. This percentage is defined as FUSED. During the design step, the Friction Diagram could be used in order to quantify the risk of skidding related to a given road layout. In this paper, the authors investigate the influence of the vehicle type on the Friction Diagram, since it was observed that the type of vehicle used in analyzing a road segment makes the values of FUSED change when the boundary conditions and the road geometry change. This aspect led the authors to identify the vehicle to be used in the skidding risk detection. This vehicle has been named as the “Design Critical Vehicle”(DCV). It allows faster detection of the road sections with high skidding risk using a single Friction Diagram and avoiding the need to perform the same analysis for various vehicle. The DCV identification could be useful in the application of the Friction Diagram Method both in road design and in checking of existing roads.