Investigation of Infrasound Radiated from Highway Bridge Owing to Moving Truck

Abstract

Several complaints arose from houses near an object bridge about rattling sounds caused by infrasound, a low-frequency noise in the 0 -20 Hz frequency range. In Japan, conventional trucks with a rear leaf suspension have vibration frequencies of about 3.0 Hz; furthermore, their tire spring vibration frequency is 10 -20 Hz. Infrasound is radiated from the bridge owing to the truck's suspension spring vibration and/or tire spring vibration. In this study, the bridge vibrations were investigated using test trucks or conventional trucks to determine the cause of rattling sounds. It was found that the truck's spring vibration caused excessive bending vibration in the object bridge; this in turn was transmitted to nearby houses as infrasound. Various preventive measures for infrasound were then considered, and their effectiveness was investigated through a simulation of the dynamic response using a running truck. The difference between each measure's effectiveness as obtained by a comparison with each simulation's result provided a clear picture about the infrasound reduction methods in consideration of both construction cost and working difficulty.