Effects of Snow Fences on Crashes and Road Closures: A 34-Year Study on Wyoming Interstate-80

This study evaluates the effectiveness of snow fences in reducing crashes and road closures on an 80.4 km remote rural section of Interstate-Highway 80 in southeastern Wyoming. No snow fences were in place when this highway was first opened to traffic in 1970, but serious snow drifting problems necessitated a large-scale snow fencing program from 1971 to 1990. The proportion of road protected by snow fences has increased to a present level of 73%, consisting of 69.7 lineal kilometers of snow fence, ranging in height from 1.8- to 4.3 m and constructed at a cost of $1,910,000. Total crash rates per million vehicles, for October through April, have declined in proportion to the percent of road protected by snow fence at a statistically significant rate of approximately 20 crashes for every 10% increase in snow fence protection. This decline in crashes is equivalent to a 75% reduction in crash rates in areas protected by snow fences, and is attributable to the elimination of snowdrifts, improved visibility in blowing snow, and reduced road ice. At the 2003–04 seasonal traffic volume of 1.9 million vehicles, the existing snow fences prevented 275 crashes, 124 injuries, and 3.1 fatalities per year. This implies an annual return of $25,000,000 on the original capital investment of $1,910,000. If the fences were replaced at current costs, and traffic volume remained constant at the 2003–04 level, these benefits yield a benefit-to-cost ratio of 47: 1, with construction cost amortized within the first year. Reduced traffic delay is another important benefit of the snow fence protection—the present snow fence system reduces road closure time by an average of 8.3 days each year, representing an additional annual benefit in the millions of dollars.