Noise measurements of highway pavements in Texas.

PDFTech ReportFHWA/TX-10/0-5185-30-5185NoiseFrictionFriction courseOpen graded aggregatesSound intensityTexasTexas Transportation InstituteTrevino, ManuelDossey, TerryTexas Transportation InstituteNTL-HIGHWAY/ROAD TRANSPORTATION-MaterialsNTL-HIGHWAY/ROAD TRANSPORTATION-Pavement Management and PerformanceUS Transportation CollectionThis report presents the results of noise testing performed on Texas pavements between May of 2006 and thesummer of 2008. Two field test methodologies were used: roadside noise measurement with SPL meters and onvehiclesound intensity measurement of noise at the tire/pavement interface. Additionally, pavement sampleswere tested in an impedance tube. Comparisons are made between the levels of vehicular noise at the roadsideand directly on the source vehicle. The FHWA Traffic Noise Model (TNM) computer program was used topredict the noise levels at roadside based on the observed traffic and geometry of the roadway, and subsequentlycompared to the noise as actually measured with precision test equipment. An important part of the study focusedon testing pavements corresponding to the New Generation Open Graded Friction Course type, a permeableasphalt design with air voids in the area of 17 percent, also known as Permeable Friction Course (PFC) in Texas.Findings indicate that roadside noise levels experienced along PFC pavements are significantly lower thanpredicted by TNM using either the "Average" or "Open Graded" pavement models included in the program.Measurements at the tire/pavement interface confirm the quieter characteristics of these surfaces. The studyresults also suggest a slight degradation of such quietness with time, but even with this small increase in noiselevels the surfaces can still be considered quieter than other pavement types. Furthermore, the increase inloudness is not significant enough to assert that these PFC surfaces cannot retain their acoustic properties overtime. As per the results obtained in this study, it can be said that open-graded pavements can be reliably used fornoise impact avoidance and abatement