Estimation of Vehicle Pass-By Noise Emission Levels from Onboard Sound Intensity Levels of Tire–Pavement Noise

As a portion of the overall research work for NCHRP Project 1-44, field tests were performed on in-service pavements to demonstrate the applicability of the onboard sound intensity (OBSI) method for quantifying the effect of different pavement types in relation to total vehicle noise emissions measured with the controlled pass-by (CPB) and statistical pass-by (SPB) methods. Testing included the simultaneous measurement of OBSI on two specific candidate test tires, CPB on test vehicles equipped with those tires, and SPB of both light and heavy-duty vehicles. With the SPB data, the relationship between OBSI tire–pavement noise and average vehicle noise emissions were examined for both light vehicles and heavy trucks. To account for site-to-site variation, pass-by results were normalized by using the measured relationships between OBSI and CPB levels for each site. On the basis of these results, it was found that SPB levels for both light vehicles and heavy trucks could be predicted accurately with a standard deviation of 0.8 dB for both vehicle categories for an average of sites that used OBSI data obtained from either of two candidate light-vehicle test tires.