The maps available to download at the bottom of this page highlight road corridors that, due to the volume and/or type of traffic, have the potential to generate significant road traffic noise.
Road corridors where mandatory requirements under the State Environmental Planning Policy (Infrastructure) 2007 (Infrastructure SEPP) apply are shown in red on the maps.
These road corridors are listed in the Infrastructure SEPP and comprise:
- Roads carrying an Annual Average Traffic Volume (AADT) of more than 40,000 vehicles.
Construction of dwellings and other noise sensitive development such as churches, hospitals and schools on land in or adjacent to the road corridor triggers the need to consider noise mitigation measures under the Infrastructure SEPP. In addition dwellings must meet specific internal noise levels for habitable rooms such as bedrooms and other living areas.
The maps highlight road corridors carrying between 20,000 and 40,000 annual average daily traffic (AADT) shown in amber. For these road corridors there are no general mandatory requirements to assess and include mitigation against road traffic noise for new residential and other noise sensitive developments.
However, it is expected that in most situations road traffic noise will adversely impact these locations (exceptions may occur where an intervening structure acts as a barrier to noise or the road is in a cutting causing traffic noise levels to be reduced)
For new developments along road corridors carrying between 20,000 and 40,000 AADT assessing road traffic noise levels and including noise mitigation measures is advisable. The noise mitigation measures should meet the NSW government’s external noise target levels in the Environmental Criteria for Road Traffic Noise and take into account the internal noise levels stated in the Infrastructure SEPP.
It is not uncommon for local planning instruments to require new developments in areas affected by road traffic noise to assess and provide mitigation measures against road traffic where needed.
Defining noise affected locations based on traffic volume
It should be recognised that traffic levels on the road network do not rise or fall abruptly, but tend to progressively grow or taper along a roadway.Traffic volumes are also not recorded on all road segments. Determining at what point along a roadway traffic levels are sufficient to trigger assessment (and where it is necessary to include noise mitigation measures) requires both measured traffic volumes and expert judgement to define the length of road corridor.
Road traffic noise levels on busy roads however, are not sensitive to small changes in traffic volume. A substantial change in road traffic volume is needed to cause a noticeable change in noise level measured over a day (7am to 10pm) or night (10pm to 7am) period. A typical approximation is that a change of 60 per cent in traffic volume measured over a day or night period is needed to cause a 2 dB (decibel) change in noise level and that 2 dB is often quoted as the minimum change in noise level that is noticeable.
So, while a level of accuracy is needed to identify roads with the traffic volume of 40,000 AADT defined in the Infrastructure SEPP 2007, the noise levels experienced at these locations are not sensitive to small changes in traffic volume.
Annual Average Daily Traffic (AADT) values used to interpolate traffic volume segments are derived from Count Station data published on Roads and Maritime Services (replacing Roads and Traffic Authority) website. The raw data has been adjusted to a 2007 baseline and converted to vehicle counts from axel pair counts where required.