Citation

Harwood DW, Blackburn RR, St John AD. Transp. Res. Rec. 1977; 624: 142-150.

Copyright

(Copyright © 1977, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

unavailable

PMID

unavailable

Abstract

The objective of this study was to establish the relationship between accident rate and skid number for various combinations of highway type, area type (urban/rural) and traffic volume. Accident rate, skid number and related data were collected for two, 1-year periods on 428 highway sections located in 16 states. An extensive statistical analysis of the data was conducted using matched-pair comparisons, regression analysis of covariance. The analyses found a small, but statistically significant, effect of skid number on wet-pavement accident rate. A linear relationship with skid number explained the variation in wet-pavement accident rate well, or better, than any simple logarithmic or polynomial function. The differences in the slope of this linear relationship for various highway type-area type-traffic volume combinations were not statistically significant, so a single common slope was used. Specific relationships between wet-pavement accident rate and skid number are presented. It was found that the slope of the wet-pavement accident rate-skid number relationship is sensitive to the dry-pavement accident rate. The sensitivity was quantified and is presented in the paper. Finally, the accident rate-skid number relationships developed in this study are compared with the relationships developed by previous researchers.