THE TARMAC CONNECTION

The author discusses the design of road surfaces which will help to improve road holding and braking performance. It is shown that such a surface must have a coarse microtexture or adequate fine-scale roughness at the 0.01 - 0.10 mm size level in order to provide good wetted friction at any speed. In addition, adequate drainage is essential, especially at the higher speeds and one way of achieving this is described, whereby the road surface is given a macrotecture or large-scale roughness - a network of relatively large and deep (1-3 mm) drainage pathways between protruding areas of fine-scale roughness which can bite into the surface of the tyre. The use of such a surface known as shellgrip is described which, on the grounds of expense can only be used at a limited number of high-risk sites; and the development and production of a less expensive material known as delugrip. The basic principle of delugrip is in the use of at least two different kinds of stone with significantly different wear rates, the finer sized stones filling the voids between the larger sized stones. By this method stone content is increased without increase in volume, and the all-important macrotexture is preserved against wear for long periods. Delugrip sections on the hammersmith flyover, London, are shown to be wearing well after three years of heavy use, maintaining a level of wet grip which is considered superior to adjacent sections with conventional BS594 hot rolled asphalt material. /TRRL/

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  • Corporate Authors:

    IPC Magazines

    66-69 Great Queens Street
    London WC2E 5DD,   England 
  • Authors:
    • CURTIS, A
  • Publication Date: 1977-1-13

Media Info

  • Features: Figures; Photos;
  • Pagination: p. 67-69
  • Serial:
    • NEW SCIENTIST
    • Volume: 73
    • Issue Number: 1034
    • Publisher: REED BUSINESS INFORMATION LTD
    • ISSN: 0262-4079

Subject/Index Terms

Filing Info

  • Accession Number: 00152827
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Report/Paper Numbers: Analytic
  • Files: ITRD, TRIS
  • Created Date: Jul 2 1977 12:00AM