This paper describes a method for determining the propensity of road surfaces to reflect light in a specular fashion when wet. A criterion called the 'specularity index' is proposed as an indicator of when a road should be resurfaced for optical reasons, and to establish the feasibility of satisfactorily lighting a given surface under wet conditions. To facilitate measurement and comparison of the luminance of the bright streaks and the dark background a box was designed containing a light source and a photometer which reads either specular reflection along the line of the lightbeam or non-specular reflection at any declination angle up to 10 degrees, the light paths being directed by a series of mirrors. The interior of the box is painted matt black and baffled to minimize stray reflections. /TRRL/

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  • Corporate Authors:

    ARRB Group Limited

    500 Burwood Highway
    Vermont South, Victoria    3133
  • Authors:
    • Knox, G W
    • Fleming, B R
  • Publication Date: 1978-9

Media Info

  • Features: Figures; Photos; References; Tables;
  • Pagination: p. 19-27
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00194027
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: ITRD, TRIS, ATRI
  • Created Date: May 26 1979 12:00AM