Johns River

Complaints Spark Earlier Testing

The RTA 1800 number has received several complaints about the noise on the new highway, as has the Minister for Roads.   In response to the community input, the Pacific Highway General Manager, Mr. Bob Higgins, wrote to the NSW Planning Minister to request that noise testing be brought forward, in an effort to resolve noise issues.

The evaluation process, completed in November 2010, involved noise monitoring by specialist acousticians, which examined whether or not the bypass is compliant with current standards and guidelines.  The operational noise monitoring was done during peak hours when all four lanes were being used.

Because the new highway segment from Coopernook to Herons Creek has no viable or likely alternate route, Mr. Higgins was able to gain Ministerial approval to bring forward the testing date, so local residents along the upgrade corridor could gain results sooner rather than later.

The RTA has produced a draft report on the noise monitoring results, and once the report is published publicly, the RTA may consider a reassessment of measures to dampen the sound for residents, in situations where such mitigation works are deemed viable by the RTA.

The Coopernook to Herons Creek project was purposefully built with noise mitigation measures incorporated in the plans, rather than tacking on abatement structures later on, which has significant  cost-savings as well over the older approaches.

The RTA originally sampled noise levels at the Johns River Public School, at the residence on Johns River Road next to Washtub Creek, and out at Wharf Road, at number 28.   Subsequent testing after the bypass was operational was completed in November 2010, and should clear the Department of Planning by mid-February.

The Sound Approach

The criteria were developed solely to address noise levels and their impacts on residences along the project.  They include factors as diverse as sleep disturbance, and whether the segment of highway is a new corridor, or replaces an old one.  

Our Johns River bypass segment is considered a new freeway corridor, and as such, is allowed to have a nighttime measurement of 50 decibels of equivalent steady sound at the residence during the hours of 10pm – 7am, and 55 decibels during the remaining daytime hours.

As a general guideline, when you walk into the Taree library, you experience an average of 30 decibels during your stay there.  The average Aussie lounge room sits at around 43 decibels, and most business offices sit around 64 decibels.  If you stand right next to a B-Double as it goes past Rosie's at 50kph, you'll catch about 90 decibels of noise.   This was experienced daily of course in Johns River before May of 2010 when the bypass opened here.

The RTA acknowledges the importance of addressing the impact of road traffic noise during road projects and recognises the direct effects traffic noise can have on those living around heavily trafficked roads.  It takes into consideration the "annoyance factor" of exposure traffic noise, which is actually based on a sophisticated formula using social surveys.  

Fifty decibels at night is the mark where extensive research has shown that ninety percent of residents don't really find it particularly annoying (answering not at all, slightly or moderately annoying on the survey) The remaining ten percent did response that the noise made them quite agitated however.  The average bedroom noise level is around 25 decibels.   Classrooms have a lower 45 decibel threshold of permitted noise level, measured from inside the classroom.

In Johns River, much of the noise complaints have stemmed from the residents living closest to the new corridor on the south side of the Johns River Road bridge, where the RTA chose to not build a large earthen noise barrier, as they did for the northern side (where residents are actually further away).  

At Moorland South, resident complaints have emanated largely from concerned Forest Road residents, where highway noise post-bypass has actually increased.  If the new highway segment going south from Pipe Clay creek past Forest Road is now generating more than 0.5 decibels more than the previous highway had (which turned eastward before Forest Road), then guidelines state that noise levels should be decreased where it is considered reasonable and feasible.   The recommended sustained noise level at night (with house windows open 20% for ventilation) is forty decibels.

Residences are measured about a meter away from the side closest to the highway.  The actual calculation of road traffic noise follows a formula which includes maximum noise levels of heavy vehicles, the distribution of levels throughout the sampling period, and ambient noise levels.  All factors are adopted into the formula at a particular level of detail, as might be needed for any subsequent abatement works.

Amongst additional measures to lower sound, the RTA recently developed a mobile engine brake noise camera, to ensure trucks coming through our communities are not exceeding noise limits, especially at night.

The Noise Abatement Program

In 2009–10, the RTA spent $2.6 million treating 57 dwellings exposed to high levels of road traffic noise.

Architectural noise treatments include sealing around doors and windows, installing mechanical ventilation and replacing doors and windows with acoustically rated units. Ten homes in the Illawarra, Hunter and Northern regions of NSW were done under the program.  Presumably more were treated as part of the actual C2HC project.

The RTA is improving the delivery of the Noise Abatement Program  (which applies to arterial roads) by reviewing the procedure for prioritising noise-affected residents for treatment and mitigation measures used for architectural treatment of residences.