Evaluation of Noise Reduction of Korean Low-Noise Pavements - Part 1: Measurements and Results of the CPX method

The traffic noise, in Korea, is officially evaluated by the roadside or residential area equivalent sound pressure level under the Standard Process for Noise and Vibration Measurement. However, since most measuring environments are not appropriate to meet the Standard Process conditions, the CPX method (ISO 11819-2) is considered as an alternative. Some studies are performed by the authors to evaluate the roadside noise reducing effect of two-layer porous asphalt (DLPA) pavement using the CPX method. The previous study showed that roadside noise-reducing effect of DLPA is more related with the measurements from the optional rear microphone rather than those from the mandatory side microphones. In this paper, the correlation between roadside noise measurement results and CPX measurement results is investigated for different ages of DLPA, in terms of noise reduction expressed in dBA. The result shows that, even though the DLPA pavement ages, the roadside noise reducing effect is still highly correlated with the measurements from the CPX rear microphone location, which is similar results with the previous study. Therefore, it may be considered that the optional rear microphone location can be used as a standard location when evaluating the roadside noise-reducing effect of DLPA. In another paper at this conference, the issues regarding the application of the CPX method for low noise pavement is also addressed.