Road Profiles, Vehicle Dynamics, and Human Judgment of Serviceability of Roads: Spectral Frequency Domain Analysis

Abstract

The serviceability rating of roads has been an interesting and important subject ever since it was introduced to measure the road performance. The present paper analytically addresses this problem—namely, linking a static road profile with the dynamic response of a vehicle to the existing road profile and to the driver's impressions and evaluation of the ride character on the road. Using a quarter car model and applying the spectral density method, analytical expressions have been derived for various response dynamic indices, such as jerk index, acceleration index, average rectified speed (ARV), average rectified slope (ARS), and the international roughness index (IRI), in terms of the pertinent physical parameters of the road and the dynamic characteristics of the quarter car. A general expression for serviceability index of roads is suggested using Fechner's psychophysical law and is verified using field data.