Abstract
The drainage asphalt pavement contains consecutive pores and has the noise reduction effect. We have analyzed the factors of the effect carrying out the site measurements and the experiments related to the drainage pavement. As a consequence, we have derived the sound power level equations of vehicles, which show the noise reduction effect of the drainage pavement at a sound source. In fact, they give us smaller values of sound power level compared to those of the dense graded asphalt pavement. On the other hand we have obtained the flow resistivity of 1, 250 kPa s/m2 for the drainage pavement as the noise reduction effect during propagation. This is smaller than that of the dense graded pavement, 20, 000 kPa s/m2, and generates the excess attenuation in the course of sound propagation. In view of the aforementioned, we have proposed the calculation method of the sound pressure level in the roadside area of drainage pavement on a basis of the A method of ASJ Model-1993, taking into consideration these factors at the sound source and during the sound propagation related to the noise reduction effect of the drainage pavement. The sound pressure levels measured along the drainage pavement have verified this method.
