Expressway noise barrier performance including durability of the acoustical property of porous asphalt pavement

摘要

Porous asphalt pavements have been widely applied to Japanese expressways as a countermeasure against road traffic noise as well as a safety measure for high speed driving in rain. Inthe noise prediction method, ASJ RTN-Model 2003 provides the acoustical treatment of thispavement, in which corrections to the power level of running vehicles and the calculationprocedure of noise attenuation by barriers are given. The prediction model also includes yearlychange in the power level due to the deterioration of surface structure of the pavement. Thenoise attenuation according to the diffraction was originally determined from the noise spectraof running vehicles at porous asphalt pavements of less than one year after laid. In this paper,the correction to the attenuation concerning the diffraction at expressways with porous asphaltpavement is proposed, which is taking account of yearly change in noise spectra of runningvehicles. The noise spectra were collected at expressways with the pavement of less than 12years after the time when the surface was first laid.