STEVEN Cooper from the Acoustic Group, an independent firm, says measurements being conducted on some of the sites in Casula by himself and others since 2005 have exceeded the allowable night-time level of 55 decibels.
Commenting on the M5 expansion plans, Mr Cooper said that when you "double the amount of traffic, the noise goes up by three decibels".
An RTA spokeswoman said an environmental assessment was on public display last year for a proposal to expand the M5, including the stretch of motorway through Casula.
The spokeswoman said the assessment would look at the impact of traffic noise and any mitigation work which might be needed.
"Details of the increased noise protection will be included in the submissions report which is expected to be finalised and published shortly," she said.
She did not respond to questions about the residents concerns or why nothing has been done if the noise has been above the allowed level.
She did not say when the RTA last conducted measurements.
Sam Eskaros, who was the Liberal candidate for Macquarie Fields, has said his party would investigate a situation he said the Labor Government had neglected.
Labor's Andrew McDonald, who is still waiting for the seat result, said he has in the past asked for an investigation into improving the noise barriers in the area.
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