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New Zealand Standard 6806

NZS 6806:2010 was prepared by an independent committee facilitated by Standards New Zealand.

The assessment method in NZS 6806 requires consideration of a number of noise mitigation options depending on the scale of a project. These options are subject to an integrated design process, in which the costs and benefits of the mitigation is considered. In some instances the best practicable option is the ‘do- minimum’ design with no specific noise mitigation.

NZS 6806 does not set rigid noise limits but gives categories (A, B and C) of noise criteria, and requires that the Best Practicable Option (BPO) be identified to mitigate road-traffic noise. The upper category (C) provides a backstop against adverse health effects, such as sleep disturbance, by requiring the insulation of houses if the external noise would not be sufficiently reduced using the BPO.

Noise mitigation options are to be assessed, and if practicable, the category A criterion should be achieved. If this is not practicable then mitigation should be assessed against category B. However, if it is still not practicable to comply with categories A or B then mitigation should be implemented to ensure the internal criterion in category C is achieved.



Altered roads

New roads

New road
> 75,000 AADT
(ie in Auckland)



64 dB

57 dB

64 dB



67 dB

64 dB

67 dB



40 dB

40 dB

40 dB

The assessment method in NZS 6806 requires consideration of a number of noise mitigation options depending on the scale of a project. Mitigation options determined using NZS 6806 will typically comprise low-noise road surfaces and noise barriers. If these are not sufficient then building-modification such as mechanical ventilation may be required so windows can remain closed.


NZS 6806 uses several specific terms. A selection of the key terms is provided below, but many have complex definitions and reference to NZS 6806 is essential.

  • Altered road - an existing road that is subject to a change in the horizontal or vertical alignment that without specific noise mitigation would cause an increase in road-traffic noise above thresholds defined in NZS 6806.
  • Design year - 10 to 20 years after the opening of a new or altered road.
  • Do-nothing - the scenario of no change to the existing road, but with traffic growth that would have occurred at the design year.
  • Do-minimum - the scenario at the design year of a new or altered road having been constructed, but with no specific noise mitigation measures implemented.
  • Protected premises and facilities (PPFs) - PPFs are the locations where road-traffic noise is assessed and for which noise mitigation measures may be required. They include spaces in buildings used for residential activities; marae; overnight medical care; and teaching.

For further information contact