Estimation of the international roughness index using structure from motion photogrammetry. Case study of a section of Busega-Mpigi Road

Abstract

This report presents a detailed case study on estimating the International Roughness Index (IRI) of a section of Busega-Mpigi Road using Structure from Motion (SfM) photogrammetry techniques. The study aimed to assess the feasibility of utilizing SfM for road surface assessment and to evaluate the reliability of IRI estimation through this approach. The photogrammetry data, obtained as secondary data from the Uganda National Roads Authority, was utilized for analysis and generating a 3D model of the road surface. Additionally, ground truth data from the Road Measurement and Acquisition System (ROMDAS) was used for validating the estimated IRI values. The absolute error of 0.168 obtained was within the recommended range of ±1.0025. This meant that for this particular research, the SfM result is a reliable measure of the IRI. However, the project had several limitations, including the study area was relatively small, so the results may not be generalizable to other areas, the data was collected at a very high flying altitude, the study did not consider the use of ground control points, and the photogrammetry data was collected at a different date as the ROMDAS data. In addition to the limitations mentioned above, it is important to note that SfM is a relatively new technology with room for improvement. However, the results of this research project suggest that SfM is a promising method for measuring IRI and has the potential to revolutionize the way that roads are managed.