@article{ref1,
title="Evaluation of accident rate-skid number relationships for a nationwide sample of highway sections",
journal="Transportation research record",
year="1977",
author="Harwood, Douglas W. and Blackburn, R. R. and St John, A. D.",
volume="624",
number="",
pages="142-150",
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.<p />",
language="en",
issn="0361-1981",
doi="",
url="http://dx.doi.org/"
}