The Good practice guide for the assessment and management of air pollution from road transport projects (CASANZ GPG) was produced by the Clean Air Society of Australia and New Zealand (CASANZ) with the support of NZ Transport Agency Waka Kotahi (NZTA) and other stakeholders.
However, practitioners need to be aware that it is not all appropriate for a New Zealand context. This page outlines what the differences are between CASANZ GPG and New Zealand best practice.
The CASANZ GPG serves a similar purpose to the NZTA Guide to assessing air quality impacts from state highway projects in terms of describing good practice for assessing and managing the effects of road transport. However, it is not specific to New Zealand and does not consider NZTA business practices, and so the scoping and screening processes outlined in the CASANZ GPG differ to the recommended methods set out in the Guide to assessing air quality impacts from state highway projects.
Guide to assessing air quality impacts from state highway projects [PDF, 1.9 MB]
While recommendations in the CASANZ GPG for undertaking detailed air quality assessments, including the discussion of best practice in relation to dispersion modelling (appendix H of the CASANZ GPG), are generally considered to represent current best practice in New Zealand, there are some key differences relevant to the New Zealand context. Key differences between the recommendations in the Guide to assessing air quality impacts from state highway projects and CASANZ GPG for detailed air quality technical assessments are set out in the table below.
Air quality practitioners undertaking detailed assessments are expected to apply professional judgement in selecting and justifying the specific methods and data sources used, and the level of detail that is considered to be required. As such, the Guide to assessing air quality impacts from state highway projects does not preclude the use of other methods or data sources where this is supported by appropriate justification.
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Aspect |
Section of CASANZ GPG |
Commentary on key differences |
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Construction effects |
Section 3.5 |
Certain high-risk activities that are not typically associated with road construction projects (such as large-scale building demolition and on-site concrete crushing) are excluded from the scope of this guide. The relevant guidance in New Zealand for undertaking a detailed assessment of these activities, and other activities such as aggregate crushing, concrete batching plants or mobile asphalt plants that may be associated with roading construction, is set out in Ministry for the Environment (MfE) good practice guidance. Good practice guide for assessing and managing dust(external link) Good practice guide for assessing discharges to air from industry(external link) |
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The method for assessing ecological effects in the CASANZ GPG has not been adopted as its applicability in a New Zealand context is unclear. For ecological impacts it is recommended that advice from an ecologist should be sought where a roading construction activity will occur within 50m of:
The MfE Ambient air quality guidelines discuss the potential effects of air contaminants on ecosystems in New Zealand and recommend guideline values to help manage ecological impacts. |
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Any assessment of dust effects used to support a resource consent application must include a FIDOL (frequency, intensity, duration, offensiveness and location) assessment in accordance with the recommendations in the MfE Good practice guide for assessing and managing dust. |
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The assessment method in the CASANZ GPG which considers highly sensitive receptors (HSRs) within 350m of the project construction footprint has not been adopted, as this is based on UK Institute for Air Quality Management Guidance on the assessment of dust from demolition and construction, which is not specific to roading projects and anticipates some activities, including the demolition of large buildings and on-site concrete crushing, which are outside the scope of this guide. The NZTA Guide to assessing air quality impacts from state highway projects recommends considering HSRs within 200m from the activity footprint. Guidance on the assessment of dust from demolition and construction(external link) |
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Operational emissions (including tunnels) |
Section 4.5 |
The assessment criteria presented in table 4.3 of the CASANZ GPG are not consistent with the New Zealand ambient air quality guidelines and standards. Refer to the NZTA Guide to assessing air quality impacts from state highway projects for relevant assessment criteria. |
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The recommendation in the CASANZ GPG for dispersion modelling of tunnel portal emissions using complex models such as GRAL is unlikely to be appropriate in a New Zealand context except for very large tunnels in urban environments. In New Zealand, alternative assessment methods, such as a comparative analysis based on monitoring data from other tunnel locations, may be sufficient. |
