About the research
The Swarco Rumble device was compared directly with asphalt rumble strips (Kansas DOT standard) for effectiveness in garnering driver attention. Three measures of effectiveness were used: vehicle speed reduction, sound levels inside the vehicle, and vibration of the vehicle body. Additionally, sound levels at the roadside were examined. A cost comparison was performed based solely on installation and removal time plus life cycle costs. Safety benefits were not quantified. The Rumbler strips performed similarly to the asphalt strips with respect to sound and vibration inside the vehicle, and with respect to speed reduction. Sound levels at the roadside were higher for the Rumbler. For a single application, the Rumbler is approximately three times as expensive as asphalt strips (roughtly $1,500 per approach for the standard KDOT configuration), but if the Rumbler units are reused the costs are very similar. It was demonstrated that the rumbler could be reused without significant loss of performance. The rumblers proved to be very secure, remaining affixed to the pavement for six weeks with the only failures occurring when a couple of the strips were improperly installed (i.e., too little adhesive was used) and when something tore off pieces of the strips (likely farm equipment inappropriately dragging a metal blade). It was recommended that the strips be allowed on KDOT construction projects, and KDOT has since approved their use.