Development of a recommended practice for evaluating rumble strip noise and vibration performance

As part of the NCHRP 15-68 project "Effective Low-Noise Rumble Strips" project, a recommended measurement program was developed for evaluating the noise and vibration performance of rumble strip designs. Two rumble strip designs located in Northern California, which included cylindrical indentations ground into the pavement at regular intervals and a continuous sinusoidal profile, were used to assess the input to a vehicle operator and the resultant exterior noise when the vehicle departed from the travel lane. Measurements were conducted on and off shoulder rumble strips at 60 and 45 mph with eight light vehicles ranging from small compact passenger cars to large sport utility vehicles. Six triaxial vibration measurements and six microphone locations were evaluated on the interior of the vehicle, and from these measurements, one primary and one (optional) secondary location for noise and vibration were selected for the recommended procedure. Vehicle pass-by measurements were also made following the procedures of AASHTO TP 98 Statistical Isolated Pass-By Method. While not required, on-board sound intensity (OBSI) testing is recommended to establish the off-strips pavement level. 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.