SKIDDING CHARACTERISTICS OF ROAD SURFACES

THE COEFFICIENTS OF FRICTION OF RUBBER TIRES ON VARIOUS ROAD SURFACES BOTH WET AND DRY WERE MEASURED FOR BOTH STRAIGHT AHEAD AND SIDEWAYS SKIDDING AT SPEEDS OF FROM THREE TO FORTY MILES PER HOUR. AN INGENIOUS SPECIAL INTEGRATING DYNAMOMETER WAS DESIGNED FOR MEASURING THE SKIDDING FORCES. TESTS WERE RUN UPON 25 DIFFERENT TYPES OF SURFACES, INCLUDING ASPHALT, TAR, ROAD OIL, PORTLAND CEMENT, BRICK, GRAVEL, CINDERS, ASPHALT PLANK, STEEL PLATES, WOOD PLANK, AND MUD ON CONCRETE. IN GENERAL A MARKED DECREASE IN COEFFICIENT OF FRICTION WAS NOTED WITH INCREASE IN SPEED, ALTHOUGH THE REVERSE WAS TRUE IN THE CASE OF THE GRAVEL AND CINDER SURFACES. IT WAS FOUND THAT THE COEFFICIENTS AT THREE TO FIVE MILE SPEEDS ARE NOT INDICATIVE OF THE VALUES AT THE HIGHER RATES OF SPEED. TYPICAL OF THE DATA OBSERVED IN THESE TESTS ARE THE FOLLOWING COEFFICIENTS OF FRICTION ON VARIOUS WET PAVEMENT SURFACES FOR SKIDDING STRAIGHT AHEAD AT THIRTY MILES PER HOUR: SANDSTONE ROCK ASPHALT 0.59 TO 0.77; SHEET ASPHALT 0.47 TO 0.63; BITULITHIC 0.50 TO 0.63; ASPHALTIC CONCRETE 0.65 TO 0.60; ASPHALTIC RETREAD 0.40 TO 0.51; ROAD OIL MIX 0.35 TO 0.50; PENETRATION MACADAM 0.20 TO 0.28; REPRESSED BRICK WITH GROUT FILLER 0.35 TO 0.48; VERTICAL FIBER BRICK WITH ASPHALT FILLER 0.38 TO 0.52; PORTLAND CEMENT CONCRETE, ROUGH FINISH 0.37 TO 0.48; PORTLAND CEMENT CONCRETE, SMOOTH FINISH 0.40 TO 0.46; MEDIUM HARD TAR MACADAM 0.66 TO 0.47; OILED GRAVEL 0.45 TO 0.46; UNTREATED GRAVEL 0.68 TO 0.71. (THE FIRST FIGURE IN EACH CASE IS FOR SMOOTH TREAD TIRES, THE SECOND FOR NON-SKID TREADS.) A DISTINGUISHING CHARACTERISTIC OF THE BITUMINOUS PAVEMENTS THAT SHOWED THE GREATEST RESISTANCE TO SKIDDING WAS THE "SAND PAPER" TEXTURE OF THE SURFACE. FROM A THEORETICAL ANALYSIS IT IS DEDUCED THAT TO BE REASONABLY FREE FROM THE DANGER OF SKIDDING A ROAD SURFACE WHEN WET SHOULD HAVE A STRAIGHT SKID COEFFICIENT OF 0.4 OR HIGHER AT FORTY MILES PER HOUR AND A STATIC OR SIDE SKID COEFFICIENT OF 0.5 OR HIGHER AT THIRTY MILES PER HOUR. ALTHOUGH AN ATTEMPT WAS MADE TO SELECT REPRESENTATIVE SURFACES IN TYPICAL CONDITION, THE RESULTS REPORTED APPLY ONLY TO THE ONES TESTED AND IT SHOULD NOT BE ASSUMED THAT THE RESULTS OF TESTS ON A PARTICULAR SURFACE ARE TYPICAL OF ALL SURFACES IN THAT CLASS. MANY TESTS ARE ALSO REPORTED SHOWING THE EFFECTS OF TIRE PRESSURE, WHEEL LOADS, TYPE OF TIRE TREAD AND TEMPERATURE. /AUTHOR/

  • Supplemental Notes:
    • Vol 13, ParT I, PP 123 - 168, 29 FIG, 1 TAB
  • Authors:
    • Moyer, R A
  • Publication Date: 1934

Media Info

  • Monograph Title: Proceedings of the Thirteenth Annual Meeting of the Highway Research Board Held at Washington, D.C. December 7-8, 1933. Part I: Reports of Research Committees and Papers
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00207156
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Sep 6 1971 12:00AM