Citation

Ryell J, Corkill JT, Musgrove GR. Transp. Res. Rec. 1979; 712: 51-61.

Copyright

(Copyright © 1979, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

unavailable

PMID

unavailable

Abstract

As part of a program to determine the most suitable method of improving the driving qualities of Canada's Highway 401 Toronto By-Pass, 18 bituminous test sections were constructed in 1974 on the existing concrete pavement. The test sections include dense-graded and open-graded bituminous mixes that contain a variety of aggregate types including traprock, steel slag, and blast-furnace slag. A comprehensive test program in which the skid characteristics of various test sections were monitored by brake-force and side-force skid trailers and texture was analyzed by use of photo-interpretation techniques is described. Skid resistance was measured in weather conditions that varied from drizzle to slush from heavy snow by using a continuously recording side-force-friction trailer. Not all of the mixes have provided the required level of skid resistance, particularly in the driving lane and the center lane where large numbers of trucks travel. The most striking results of the project are (a) the excellent performance of bituminous mixes that contain crushed traprock or slag screenings as the fine aggregate and (b) the low skid resistance of many mixes in which the fine aggregate consists of natural sand blended with limestone screenings. All mixes were characterized by a general decline in skid resistance during the first four years as texture depths were reduced by compaction under traffic. The first phase of pavement improvement on the Toronto By-Pass, in which bituminous overlays were used with an open-graded surface-course mix, is described. Data on mix composition, skid resistance, and noise characteristics are also presented.