Longitudinal irregularity of road surfaces: depths under rolling straight-edge versus International Roughness Index

Undulating surface on newly constructed or rehabilitated roads is not unusual in Malaysia. Presently, the occurrence of irregularity on the road surface in the longitudinal direction is restricted by the permissible number of depths as measured by an instrument called the rolling straight-edge as stipulated in the Standard Specification for Road Works of Public Works Department, Malaysia (JKR). This test method is widely used in developing countries including Malaysia as it is practical and relatively cheap. However, recent developments have seen an increasing usage of more modern and sophisticated equipment for measuring road surface irregularity in this country. In the new Standard Specification for Road Works of JKR, the usage of rolling straight-edge has been replaced with the ARRB Walking Profiler or equivalent equipment. However, these relatively new instruments yield a surface irregularity parameter which is different from the normal depths measured under the rolling straight-edge. This parameter is known as the International Roughness Index (IRI). Furthermore, the Walking Profiler is more expensive than the rolling straight-edge. In addition, there is no existing correlation between the permissible number of depths under the rolling straight-edge and the IRI. As such, the main objective of this paper is to establish a correlation between the IRI as measured by the Walking Profiler or equivalent equipment, and the normal depths as measured under the rolling straight-edge in measuring longitudinal irregularity on road surfaces. Measurements of longitudinal irregularity using both methods were carried out on a number of existing road surfaces which were prominently undulating as well as on the surface of selected newly rehabilitated roads.


  • English

Media Info

  • Media Type: Digital/other
  • Features: Figures; Photos; References; Tables;
  • Pagination: 17p
  • Monograph Title: 24th World Road Congress Proceedings: Roads for a Better Life: Mobility, Sustainability and Development

Subject/Index Terms

Filing Info

  • Accession Number: 01516057
  • Record Type: Publication
  • ISBN: 2840602679
  • Files: TRIS
  • Created Date: Feb 26 2014 3:46PM