Tire noise resulting from open grid bridge decks

When a vehicle crosses the grid section of an open grid bridge deck, a tonal noise is generated. The tonal character of the noise is a consequence of the periodic excitation of both the tire and the grid. The excitation comes from the interaction between the vehicle tire and the periodic grid members. In this thesis, the parameters that control the level and frequency of the generated noise are investigated, with emphasis on quantifying the contribution to the overall noise level of the noise from the tire. The work in this thesis includes both laboratory and field measurements as well as theoretical analysis based on a ring model of the tire. By determining radiated acoustic power from the tires relative to the input force, the sound pressure level radiated from the tires when they cross the open grid deck is estimated. The results of this study show that the tire is the dominant source of noise on open grid bridges and in order to reduce the overall radiated noise, the excitation of the tires by the grid must be reduced. This can be accomplished by either infilling the grid deck or designing the grid to reduce the severity of the periodic excitation force.