Pass-by Noise Analysis of Heavy Duty Trucks

As part of the NCHRP Project 25-45, pass-by levels were measured for 1,289 heavy duty trucks operating on 20 sites including multi-lane highways and more rural two-lane roadways. These sites included uphill, downhill, level sites and accelerating and cruising conditions at speeds from below 45 mph to 70 mph as well as nine different pavement types. This research was designed to develop a more comprehensive understanding of truck noise emissions and noise sources. In this paper, the frequency spectra for these pass-bys are considered from 25 to 10,000 Hz under the measurement conditions specified in the AASHTO TP 389-20 procedure for statistical isolated pass-bys. These data are enhanced by results from the 2009 NCHRP Report 635 entitled Acoustic Beamforming: Mapping Sources of Truck Noise and from Caltrans research on truck tire noise. The findings of these various studies are presented in order to develop a more comprehensive description of heavy-duty truck noise emissions.