Precise International Roughness Index Calculation

Roadway infrastructure management focuses on quality of the road surfaces which influences the pavement longevity and riding quality. The road surface quality can be expressed in many ways from which the International Roughness Index has been recognized widely around the developed countries. This paper summarizes the derivation of International Roughness calculation and proposes a new numerical method for its computation. Compared to original Sayers's method, it does not use iterative approximation, which makes it much faster for non-uniformly sampled road data. This is useful, for example, for profiles generated from LIDAR point clouds. The method can be used for arbitrary polynomial model of segments between elevation samples. Except the Fortran code listed in the original paper, the code for the original algorithm has not been publicly available and most researchers relied on the ProVAL software with several limitations, including uniform sampling, the lack of automation, and little control over the influence of resampling methods and the initialization of the quarter-car simulation procedure. We provide Matlab codes for both the original method and the algorithm newly proposed in this paper.