Safety Effectiveness of Variable Speed Limit System in Adverse Weather Conditions on Challenging Roadway Geometry

This paper examined the interaction between roadway geometric char-acteristics and adverse weather conditions and their impact on crash occurrence on rural variable speed limit freeway corridors through mountainous terrain. As a quantitative measure of the effect of geomet-rics in adverse weather conditions, a crash frequency safety performance function that used generalized linear regression was developed with explanatory variables including snow, ice, frost, wind, horizontal cur-vature, and steep grades. This research concluded that the inter action between grades and horizontal curves with weather variables had a significant impact on crash occurrence. The research suggested that dis-tinct variable speed limit strategies should be implemented on segments with challenging roadway geometry.