In Illinois a disproportionate number of wet-weather accidents are associated mostly with intersections, curves, hills, railroad crossings, and interchange areas where a driver's maneuver demand exceeds the available pavement friction. Review of 226 such sites indicated that friction numbers (FN) ranged from 18 to 53. Of the total number of sites, 59 percent had an FN below 30, and 34 percent ranged between 30-36 while only 7 percent exceeded an FN of 36. An equally important finding was that one-third of the high-accident sites not having a disproportionate number of wet-pavement accidents also had friction numbers below 30. A long-term strategy for reducing wet-weather accidents involves upgrading and prolonging friction characteristics in new as well as in existing pavements. Recent specification changes limit the use of crushed stone and require either slag or a 50-50 blend of slag and crushed dolomite or slag and crushed gravel in bituminous surface courses depending on highway class and traffic volume. A portland cement concrete special provision requires that the final finish be obtained by use of an artificial turf drag immediately followed by a mechanically operated metal-comb transverse grooving device. In existing surfaces, friction can be improved by bituminous resurfacings containing coarse aggregates with high friction characteristics or by grooving, planing, milling, profiling, repaving, and acid etching. Sometimes, wet-pavement accidents can be reduced by lowering driver demand instead of improving friction characteristics. /Author/

  • Supplemental Notes:
    • Study title: IHR-86, Skid Resistance of Pavement Surfaces. This study is conducted in cooperation with the U.S. Department of Transportation, Federal Highway Administration.
  • Corporate Authors:

    Illinois Department of Transportation

    126 East Ash Street
    Springfield, IL  United States  62706
  • Authors:
    • Dierstein, P G
  • Publication Date: 1977-5

Media Info

  • Pagination: 41 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00185247
  • Record Type: Publication
  • Source Agency: Federal Highway Administration
  • Report/Paper Numbers: FHWA-IL-PR-60 Intrm Rpt., FCP 41H3-304
  • Contract Numbers: IHR-86
  • Files: TRIS, USDOT
  • Created Date: Feb 27 1979 12:00AM