Operational noise - Mount Ousley interchange


Project overview

Transport for NSW follows detailed procedures that provide a consistent process across NSW for the assessment of traffic noise impacts.

Transport for NSW understands noise can be a disruption to local communities during the construction and operation of major road projects.

Transport for NSW is building an interchange on the M1 Princes Motorway at the base of Mount Ousley. The interchange will replace the existing intersection of the Princes Motorway and Mount Ousley Road, bringing greater connectivity, safety and efficiency to those travelling through the gateway to Wollongong.

Road traffic noise (also known as operational noise) was assessed and mitigation measures were developed as part of the Review of Environmental Factors (REF) in 2017 and the Review of Environmental Factors Submissions report in 2018. The REF and Submissions report details operational noise mitigation measures to be included in the project, based on a concept design.

We seek to reduce road traffic noise at the source through careful road design and mitigation measures such as noise walls or barriers. Where noise goals cannot be achieved through at-source measures, the next step may be to implement at-house noise treatments.

Operational noise – Frequently asked questions

What is operational noise?

The motorway provides a source of road traffic noise in areas nearby. This is what we call operational noise.

How is operational noise assessed?

We use the same methodology and guidelines for management and mitigation of operational noise on all state roads.

The NSW Environment Protection Authority Road Noise Policy states what traffic noise levels at houses should be for new and upgraded roads.

The NSW Road Noise Policy can be found in the featured document section on this page.

How is operational noise measured?

The measurement unit for sound and noise is decibels (dB). A sound level in dB represents the sound pressure level, which is the amount of sound a listener receives.

As sound levels near a road may vary, such as when a truck is driving past, the LAeq (Equivalent Continuous Level) measurement is used to show an average noise level over a given period.

How will operational noise be managed?

The project aims to reduce operational noise by, building noise walls and at-property noise treatments to eligible properties.

We will be building or extending noise walls in three locations.

  • A five metre noise wall along the northern side of the motorway and the southern side of Dumfries Avenue, between the end of the existing noise wall and Foothills Road.
  • A five metre noise wall along the southern side of the motorway and northern side of Falder Place, between the mid-way point of Binda Street and the new western roundabout.
  • A three and a half metre noise wall along the southern side of Mount Ousley Road, between Gowan Brae Avenue and the cul-de-sac at the western end, continuing south for about 40 to 50 metres to shield the properties at the western end of Mount Ousley Road.

We will carry out at-property noise treatments at homes where noise levels are predicted to exceed the road traffic noise criteria.

What is at property treatment?

To minimise the impact of our project on local residents, we are delivering at-property noise treatment to eligible properties. Noise treatment refers to architectural acoustic measures which aim to improve the sound resistance of properties, such as window and door upgrades.

Providing at-property noise treatment is a complex process and involves a number of different steps. It is an extensive process as every property is different and requires a tailored package of treatments. For some properties, we also need to seek approval from Owners Corporations for certain treatments.

Project documents

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Featured documents