Development of a Recommended Practice for Evaluating Rumble Strip Noise and Vibration Performance

A measurement program was completed to develop recommended procedures for determining the noise and vibration performance of rumble strip designs as part of the NCHRP 15-68 project “Effective Low-Noise Rumble Strips.” Measurements were conducted on and off shoulder rumble strips on eight light vehicles ranging from small compact passenger cars to a large sport utility vehicle. Two rumble strip designs were included to assess the input to a vehicle operator and resultant exterior noise when the vehicle departed from the travel lane. The first design consisted of cylindrical indentations ground into the pavement at regular intervals, and the second was a continuous sinusoidal profile. Triaxial vibration measurements were made at six locations, including the steering wheel and column, the seat cushion and track, and the front and rear spindles. Interior noise was measured at six locations, one at the operator’s outward ear and five around the front seat passenger position. From these measurements, the recommended procedure was narrowed to include one primary location for noise and one for vibration as well as optional secondary locations for each. Vehicle pass-by measurements were also made following the procedures of AASHTO TP 98 Statistical Isolated Pass-By Method. The measurements were performed at 60 mph (97 km/h) and 45 mph (72 km/h). The recommended procedure is intended to be used by transportation agencies and other practitioners to assure comparable results when evaluating existing and alternative rumble strip designs. The optimized rumble strip design will produce minimal exterior noise while maintaining sufficient warning input to the vehicle operator.