Factors that Influence the Effectiveness of Rumble Strip Design

This study focuses on the impact of vehicle speed, vehicle type, pavement type, and rumble strip design (e.g., application method and dimensions) on the level of sound change that motorists perceive when they traverse rumble strips. Through data collected for this study and from previous research, it was found that sound change is based on the ability of a rumble strip design to convert kinetic energy effectively from vehicle tires into sound. The factors investigated in this study and their impact on sound change are as follows: (a) Width, length, and spacing should be adequate to allow for maximum tire displacement while the vehicle tires are traversing rumble strips. Sound levels will increase as strip width and length increase until the tires are able to obtain maximum displacement. For raised rumble strips, sound will increase as spacing increases until maximum tire displacement is reached. (b) Provided that width, length, and spacing are not limiting maximum tire displacement, sound increases as rumble strip depth or height increases. (c) Milled, rolled, button, profiled, and formed rumble strips can produce adequate changes in sound for drivers of passenger vehicles provided the appropriate design is used. (d) Only milled rumble strips produced an adequate change in sound for drivers of commercial vehicles. (e) As the roughness of the pavement surface increases or as the speed of a vehicle increases, so does the ambient noise, which means that more aggressive rumble strip designs are necessary.