The long-awaited noise report on the trial of diamond grinding on the Pacific Highway near Valla has found the treatment helped to reduce noise levels for home owners in the local community with no further noise treatments required.
Roads and Maritime Services Director Northern Anna Andrews said measurements taken for the report show a general trend of lower noise levels following the grinding trial.
"The most significant reductions in noise were typically seen in vehicles such as cars, with the reduction in noise for heavy vehicles dependent upon location," Ms Andrews said.
"Overall the report found the diamond ground surface produced comparable noise levels to the traditionally 'low noise' pavement used on other areas of the Pacific Highway."
This noise report followed the cutting of grooves into the highway's surface north and south of the existing low noise asphalt pavement surface for around six kms near Valla, completed in October last year.
The report includes measurements taken by an independent specialist (SLR Consulting Pty Ltd) at four sections of the highway, both before and after the grinding was completed as part of the Nambucca Heads to Urunga Pacific Highway upgrade project.
Measurements were made using both Statistical Passby Method (SPB) and On-Board Sound Intensity (OBSI) vehicle mounted devices at each test site.
The SPB method measured roadside noise levels from passing vehicles and showed a general trend of lower noise levels after the grinding trial. The most significant reductions were typically seen in cars with the reduction in heavy vehicle noise being more variable depending on the location.
The report said the variation is expected to be due to the inherent variability in roadside noise levels emitted by trucks within the same categories and the relatively small sample size of vehicles in these classes.
The OBSI method directly measured surface noise at the interface of the road pavement and vehicle tyre and also found lower noise levels post grinding.
"Roads and Maritime is continuing to collate the results of a second survey of community feedback following the trial, with the details to be made public in the coming weeks," Ms Andrews said.
Ms Andrews said the results of this survey will assist the project team in gaining an understanding of the community's views on the key issues regarding the trial.
"Grinding further sections of the Pacific Highway will be considered in line with community requirements, road classification, and suitability for the location," she said.
RMS has said with the project meeting the noise goals and the trial demonstrating diamond grinding resulted in similar benefits to traditional low noise surfaces, no further road noise treatments will be implemented at Valla.
A copy of the report can be found by visiting www.pacifichighway.nsw.gov.au by typing 'noise report' in the search tool.