The objective of this study was to investigate the following aspects of rumble strips: the optimum height and width of elements in a rumble strip pattern, spacing between them, the effect of grouping elements into sets, the effects of speed on design criteria, and driver reaction to the audible and physical stimuli produced by rumble strips. A survey of design and usage in other states was conducted; and the results show that even though 35 of the 44 responding states have installed rumble strips, only five have warrants for usage.
Two types of rumble strip design were evaluated -- one with a constant spacing between elements and another with variable spacing between elements. Simulated tests using strips of plywood showed that a distance of 10 feet (3.0 m) between elements, a strip width of 4 inches (102 mm), and a strip height of 1/2 inch (13 mm) produced the best results. Based on audible and physical stimuli, it was determined that the rumble time should not exceed 3/4 second of continuous rumble for any pattern.
Evaluation of field installations failed to show a statistically significant difference in speeds for either the constant-spaced pattern or variable-spaced pattern. Based on these installations and controlled-spacing tests, it appears that the constant-spaced pattern should continue to be used. Polyvinyl strips were installed without much success because of adherence problems. A double layer of reflective marking tape performed satisfactorfly with regard to durability and reflectivity; however, the rumble effect was slight
