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.
We understand 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 as part of the Mount Ousley interchange Review of Environmental Factors (REF) in 2017 (PDF, 7.27 MB), the Submissions Report in 2018 (PDF, 1.23 MB) and the Addendum REF in 2022. These assessments identified potential operational noise impacts from the project and mitigation measures to manage these impacts including road design, noise walls and at-property 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.
The M1 Princes Motorway at the intersection of Mount Ousley Road experiences high traffic volumes, with more than 50,000 vehicles per day using this route. For many of the residents and other sensitive receivers located near the motorway, high levels of operational noise exist as a result.
How is operational noise assessed?
Operational road traffic noise impacts are assessed in accordance with the NSW Road Noise Policy (NSW EPA, 2011) the Road Noise Criteria Guideline and Road Noise Mitigation Guideline (Transport for NSW, August 2023 and March 2022), and the noise mitigation strategies applied to the project are consistent with these policies and guidelines.
Links to these documents can be found in the section below.
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 through road design and by, building noise walls and carrying out 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.
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
Some documents on this page may not comply with accessibility requirements (WCAG).
If you are having trouble accessing information in these documents, please contact us.