The impact of noise on nearby residents from the operation of the Te Aranui o Te Rangihaeata – Transmission Gully Motorway has been a key consideration since the early stages of the project and throughout the consenting phase.
The Board of Inquiry (BOI) set certain consent conditions to manage noise effects, when it approved the project in 2012. This included detailed acoustic modelling to check the proposed design at the houses alongside the route. It took into account the terrain, the future number and type of vehicles using the road, and the road surface type before construction started. Noise levels were set that reflected the New Zealand Standard for new roads, but with some modifications that make the requirements more stringent. An additional requirement was imposed to investigate a small number of dwellings.
Noise levels were assessed before and during construction, and then once the motorway was built and opened to traffic. The BOI required a verification to ensure the motorway had been constructed in accordance with the originally modelled design, and to take measurements at some representative locations to check that the model predictions were realistic.