EFFECT OF ROAD ROUGHNESS ON VEHICLE BRAKING

THE LOSS OF TIRE BRAKING FRICTION DUE TO ROAD ROUGHNESS WAS SIMULATED AND MEASURED EXPERIMENTALLY IN A TEST MACHINE DESIGNED TO PRODUCE SIMULTANEOUS WHEEL SLIP AND VERTICAL VIBRATION OF THE CONTACT SURFACE. EQUIVALENT ROUGHNESS AMPLITUDES AS GREAT AS 0.7 IN. AND ROUGHNESS FREQUENCIES (VELOCITY/WAVELENGTH) AS HIGH AS 14 HZ WERE COVERED. WHEEL SLIP WAS VARIED BY DISCRETE AMOUNTS TO INCLUDE THE VALUES NORMALLY ASSOCIATED WITH MAXIMUM FRICTION. THE DYNAMIC FRICTION FORCE FOUND IN EACH TEST RUN WAS TIME-AVERAGED AND EXPRESSED AS A PERCENTAGE OF THE HIGHEST OBSERVED AVERAGE TO MINIMIZE THE EFFECTS OF TEMPERATURE, SURFACE CONDITIONS, AND OTHER SECONDARY CONSIDERATIONS. RESULTS SHOW SIMULATED ROUGHNESS AMPLITUDE AND FREQUENCY TO HAVE A STRONG INFLUENCE ON THE AVERAGE FORCE AVAILABLE FOR BRAKING: FRICTION LOSSES WERE 30 PERCENT AT 0.04 IN. AND 14 HZ, AND 90 PERCENT AT 0.71 IN. AND 6 HZ. WHEEL SLIP AND THE DEAD-WEIGHT LOAD ON THE TIRES WERE FOUND TO HAVE A LESS DRAMATIC EFFECT OVER THE RANGE TESTED. THE MOST IMPORTANT CONCLUSION REACHED IS THAT FRICTION PREDICTIONS WITHOUT ROAD PROFILE CONSIDERATION CAN RESULT IN GROSS ERRORS AND MAY BE ONE OF THE CAUSES OF LACK OF CORRELATION OF FRICTION DATA.

• Record URL:
  http://onlinepubs.trb.org/Onlinepubs/hrr/1973/471/471-007.pdf
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/isbn/0309022568
• Supplemental Notes:
  • Publication of this paper sponsored by Committee on Surface Properties Vehicle Interaction. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved.
• Authors:
  • Wambold, J C
  • Brickman, A D
  • Park, W H
  • Ingram, J
• Conference:
  • 52nd Annual Meeting of the Highway Research Board
  • Location: Washington District of Columbia, United States
  • Date: 1973-1-22 to 1973-1-26
• Publication Date: 1973

Media Info

• Media Type: Print
• Features: Figures; References;
• Pagination: pp 76-82
• Monograph Title: Evaluation of pavement surface properties and vehicle interaction
• Serial:
  • Highway Research Record
  • Issue Number: 471
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Braking; Friction; Pavements; Roughness; Simulation; Smoothness; Testing; Tires
• Old TRIS Terms: Pavement smoothness
• Subject Areas: Highways; Pavements; Vehicles and Equipment;

Filing Info

• Accession Number: 00207641
• Record Type: Publication
• ISBN: 0309022568
• Files: TRIS, TRB
• Created Date: Apr 27 1974 12:00AM