Citation

Stinson KW, Roberts CP, Gray BE, Rhodes EO, Fleming EM, Martin GE, Schlesinger GF, Moyer RA. Highw. Res. Board Proc. 1934; 1934.

Copyright

(Copyright © 1934, National Research Council (U.S.A.), Highway Research Board)

DOI

unavailable

PMID

unavailable

Abstract

Tests to determine the coefficient of friction between automobile tires and road surfaces were made using a two- wheel trailer connected to a towing car through a hydraulic dynamometer. All runs were made during rainfall, the test speeds were maintained throughout the application of the brake, and data were obtained to determine the rolling and sliding coefficients of friction. smooth and nonskid tires were used and tests were made on portland cement concrete, brick and bituminous road surfaces at speeds of five to forty-five miles per hour. Two important trends shown by these tests are: that the coefficients of friction on all road surfaces decrease with increase of speed; and that the difference between the rolling and sliding coefficients increases with increase of speed. These relations are very significant from the standpoint of safety. In these tests the straight ahead sliding coefficients of friction between nonskid tread tires and the various wet road surfaces tested at thirty miles per hour ranged as follows: bituminous concrete 0.54 and 0.42; sheet asphalt 0.41; portland cement concrete 0.41; vertical fiber wire cut brick whitewashed before application of filler 0.52; vertical fiber wire cut brick partially covered with asphalt 0.23; repressed brick tar filler (none above surface of brick) 0.35; repressed brick partially covered with asphalt filler 0.24. The results quoted apply only to the specific surfaces tested and should not be assumed to be typical of all surfaces in the various classes.