Key to the NZS 6806 process is the determination of the BPO in a robust and consistent manner. The following provides a summary of the actions required for NZTA projects during the determination of the BPO.

1. The project should be split into discrete assessment areas, whereby each area is subject to the same mitigation options. In urban environments separate assessment areas should be used for each side of the state highway.
2. The project acoustics specialist should develop a number of noise mitigation options for each assessment area. One of the mitigation options must be designed to achieve compliance with the Transit guidelines. Example mitigation option maps are provided to standardise the formats for displaying structural mitigation and PPF noise category. In some instances, to aid understanding of a mitigation option it may be necessary to provide cross-sections showing roads, barriers and PPFs. Examples of cross-sections generated by acoustics modelling software are also provided.
3. The project acoustics specialist should calculate the benefit-cost ratio (BCR) for each mitigation option using the spreadsheet template.The project acoustics specialist is required to enter a summary of the results of each mitigation option, along with the cost and benefit (including the BCR spreadsheet) on the project page of this website
4. The project acoustics specialist should prepare an assessment matrix for each assessment area using the template and circulate the matrices with the options summary papers to the project team.
5. All relevant project team members should complete the matrix including input from the NZTA Asset Manager and landscape/visual/urban design.
6. The responses to the matrices should be collated and reviewed by the project manager, planner and acoustics specialist, to select the BPO.
7. For large, complex and high risk projects it will usually be necessary to hold noise mitigation workshops to review the matrices before determining the BPO.
8. Ideally the BPO will be determined by consensus at the noise mitigation workshop. If consensus cannot be achieved then a suitably qualified expert with a holistic view is responsible for balancing the different considerations and making a judgement as to which option constitutes the BPO.