Rumble Strips in North Dakota: A Comparison of Road Segments, Safety, and Crash Patterns

Rumble strips and rumble stripes are a recommended strategy for crash reduction. The North Dakota Department of Transportation initiated rumble strip use in the 1970’s and greatly expanded application of rumble stripes through a statewide initiative in recent years. This study of four intervention and two control road segments shows positive results with regard to crash incidence in before and after comparisons. The crash rates comparison considers crash severity, vehicle type, roadway factors, crash type, and contributing factors. A reduction in all crashes and crash severity, in terms of the most serious fatal crashes, is found in comparing crash rates per 100 million vehicle miles traveled (VMT) in times periods before and after the installation occurred. Note that on some road segments, confounding factors such as impaired driving, appear to be significant factors in the crash rates so the safety benefit attributable to the rumble strips/stripes cannot be easily assessed. In addition, results should be used with caution – especially those for fatal crashes – because of the limited number of observations. Future studies may produce more robust results as additional road segment and crash rate data can be incorporated.