Overview
Transport for NSW released two updated documents in April 2025: the Road Noise Criteria Guideline and the Road Noise Mitigation Guideline. The criteria guideline supersedes Practice Notes I and III of the 2001 Environmental Noise Management Manual, and the Mitigation Guideline supersedes RMS 14.584 and Practice Notes (iv), (iv-a) and (iv-c). They align with the NSW EPA’s Road Noise Policy 2011 but include Transport-specific procedures for planning, design, and construction.
Who This Affects
The Road Noise Criteria Guideline is most relevant for project development managers, environmental staff, project implementation managers, acoustical consultants, and regulatory agencies involved in planning, approving, and delivering road projects. It generally applies in the final stages of project concept design, the environmental impact assessment phase, and detailed design stages. It also applies to all public roads and classified roads managed by Transport for NSW.
The Road Noise Mitigation Guideline is most relevant for project development managers, environmental staff, project implementation managers, NAP managers, and acoustic consultants. It generally applies in the final stages of project concept design, the environmental impact assessment phase, and detailed design. It also applies following post-construction operational noise monitoring where re-evaluation of mitigation is required, to minor works where noise levels increase by more than 2.0 dBA, and to NAP noise mitigation measures.
Road Noise Criteria Guideline
The Road Noise Criteria Guideline establishes how Transport for NSW sets and applies noise limits for new, redeveloped, and minor road projects. The guideline differs from earlier methods by basing criteria on the road project near a receiver rather than existing background levels. For new roads, the total noise level from all roads is assessed against the new road criteria—unlike the 2011 Road Noise Policy, which only considered the noise directly generated by the new road. This approach ensures mitigation reduces the overall noise a receiver experiences, not just the incremental contribution from a single source.
The guideline classifies road projects into 3 categories as described below:
- new roads: construction in an undeveloped corridor, a bypass, or a substantially realigned road upgrade
- redeveloped roads: widening or adjustments that do not substantially realign the road, duplications adjacent to or within the existing corridor, introduction of on/off ramps, or upgrades involving increases in heavy vehicles by 50 percent or more
- minor works: curve straightening, intersection widening, turning bay extensions, and works that do not increase traffic-carrying capacity or accommodate significant increases in heavy vehicle traffic
This classification determines which criteria apply to receivers within the study area.
The standard study area extends 600 metres from the outermost traffic lane, adjustable for rural or dense urban environments. All sensitive receivers within this area must have the relevant noise assessment criteria determined. Transition zones are introduced to provide a gradual change in criteria between new and redeveloped road segments, determined by contribution differences between the two sources.
Together, these features create a more transparent, consistent, and outcome-focused approach to assessing and managing road traffic noise across Transport for NSW projects.
Road Noise Mitigation Guideline
The Road Noise Mitigation Guideline provides a consistent approach for evaluating, selecting, and designing appropriate combinations of noise mitigation measures once project noise levels exceed the criteria defined in the Road Noise Criteria Guideline.
The guideline requires all mitigation measures to meet a “feasible and reasonable” assessment before being adopted. It outlines this test as a central principle, ensuring that mitigation achieves equitable outcomes for affected communities and is both practical and cost-effective. The guideline directs that noise reduction should first be pursued during corridor planning and road design, where it can be integrated efficiently and aligned with broader urban design objectives. Only where these early opportunities are limited should later-stage treatments, be considered. This approach ensures that mitigation is proportionate, defensible, and consistent across all projects.
The guideline introduces cumulative and acute triggers for identifying when receivers qualify for mitigation. A receiver qualifies for consideration of noise mitigation only when:
- the total noise level exceeds the relevant Road Noise Criteria Guideline limit
- the total noise level also exceeds either the cumulative limit and/or the acute noise level
The cumulative trigger applies when:
- total traffic noise exceeds the Road Noise Criteria Guideline limit by 5 dBA or more.
The acute trigger is reached when noise levels are:
- 65 dBA LAeq(15hr) during the day, measured one metre from the façade
- 60 dBA LAeq(9hr) at night, measured one metre from the façade
Without the cumulative limit, receivers already exposed to high noise levels but experiencing only small increases would not qualify for mitigation unless their total noise is acute, reaching up to 10 dBA above the applicable criteria. This dual threshold provides a fairer, evidence-based basis for determining which receivers require treatment.
The guideline defines a hierarchy of controls:
- reduce noise through planning and design decisions
- apply quieter pavement surfaces
- apply noise mounds
- apply noise walls
- apply at-property treatments only when other measures are not feasible or effective
To justify the use of quieter pavements, mounds, or walls, there must be at least four closely spaced receivers that would benefit, and the final combination of mitigation options must then be assessed in more detail to confirm its suitability.
Why This Matters?
If your organisation plans, designs, or delivers Transport for NSW projects, the updated Road Noise Criteria Guideline and Road Noise Mitigation Guideline change how road traffic noise must be assessed and managed. Assessments must now include total noise from all nearby roads, not just the new or upgraded road, ensuring that mitigation reflects the full noise exposure experienced by receivers. The updates also introduce new triggers for when mitigation is required, a clearer feasibility and reasonableness test, and a defined hierarchy of controls for quieter design and construction.
These changes may affect how project noise assessments are scoped, modelled, and approved—especially during the environmental impact and detailed design stages. Organisations involved in road infrastructure should review current practices and confirm alignment with the new guidelines. For project-specific advice or support with implementing these updates, contact our team at [email protected].
