Kezia emphasises that ultimately, judging whether there is too much noise is a matter of personal preference and the environment.
Richard Jackett is one of the foremost experts on the impact unwanted road noise has on people and communities – he’s spent most of his career assessing it.
“Fundamentally it comes down to how acceptable noise is. We have done much of the research that underpins road noise guidance and standards in New Zealand. What was deemed reasonable for New Zealand road traffic is 57 decibels.”
However, Richard points out that New Zealand’s standardised algorithms for predicting traffic noise were last reviewed 30 years ago, highlighting there is room for improvement.
“The model has done a good job, but it was developed at a time when the top selling cars were the VN Commodore and EA Falcon. Things have changed dramatically since then and we need to consider a broader range of scenarios, such as intersection and night time noise.”
It takes time to respond to such changes due to the requirement for robust evidence of the problem. Because noise assessments are often brought before council chambers or the Environment Court, updating regulation is a significant undertaking. New limits and models will also change how large projects are designed and how planners tackle residential developments.
Interestingly, Richard says the expectation that road noise will be drastically reduced with the shift towards electric vehicles is incorrect.
“It’s the interaction between the tyre and the road that generates most of the noise – certainly for cars – so quieter engines and no exhaust won’t make an urban environment that much quieter. The big shift will come when we see more electric buses and trucks.”
Richard’s team helps with planning decisions, investigates noise complaints and recommends solutions.
“We try to get in as early as possible in the decision making to ensure the road alignment has the least amount of impact – that’s the best thing we can do for people. The next thing is to find the road surface that generates the least amount of noise.”
Ideally road noise should be limited at source, he says, rather than relying on expensive interventions such as noise walls, which cause shading, or the installation of double-glazing on houses.
“To be honest, we get limited traction on where the road goes because there is so much involved in making those decisions, but we can influence the road surface. Greater investment on the surface means less spend on mitigating with barriers, and house treatments, so it’s a pretty compelling case.”
This approach has been successfully applied to large projects including the Waikato Expressway and Southern Links.
Richard has seen first-hand the impact noise has on people, and says that even small changes have a tangible effect on the people who have to live with it.
“I was involved in a research project that went into people’s houses and talked to them about a recent change in their noise exposure. They talked about sleeping with windows closed, spending more time in the kitchen because it was easier to talk there, listening to the TV with the volume on level 20 rather than 15.”
There’s always a balance he says, the trick is in finding a solution that satisfies both sides and being able to justify it with evidence.
