NZ Transport Agency releases Ruby Bay Bypass noise levelreport


The NZ Transport Agency has released results of an independent report into noise levels on the Ruby Bay Bypass, which show that traffic noise in the Dawson Road area is within acceptable levels.

The report was commissioned from infrastructure experts URS New Zealand after a public meeting in June, where local residents raised concerns about an increase in road-traffic noise levels after the finishing coat of seal was put on the road’s surface in February 2012. Applying an additional seal coat is normal practice for new roads.

The Bypass is part of State Highway 60 (SH60) and was designated as a state highway in 2000. The road itself opened in October 2010, and now carries close to 5000 vehicles per day between Motueka and Richmond. 

Regional Performance Manager Mark Owen said that when the road was originally designated, noise conditions required the Transport Agency to mitigate noise from the bypass at houses that had already been built in the adjoining area. 

“From the beginning, the Transport Agency agreed that we would put appropriate measures in place if noise levels at these properties exceeded acceptable noise guidelines. 

“The Bypass’ design was influenced by the recommendations of noise studies carried out in 1999 and 2006. Measurements of noise in these studies, along with predictions of the future noise levels, meant that earth bunds and noise barriers were built at a number of locations that appeared sensitive to noise.

“The 2006 study also noted that a number of houses had been or were being built after the designation was in place.  While the Transport Agency was not required to consider the impact of noise on these houses, earth bunds were built to help shield a number of these properties from Bypass noise as well.”

Mr Owen said that when complaints about the finishing coat of seal were raised, the Transport Agency wanted to make sure that road-traffic noise on the Bypass was still within acceptable levels. 

“After hearing local residents’ concerns, we agreed that it was important to investigate them thoroughly.  Nine measurement locations were agreed, including properties named in the original conditions and an additional number that were not.

“We also measured noise levels at two locations next to the state highway: one on the Bypass and the other at another location with a similar surface to the Bypass before the finishing coat of seal was applied.  This meant that we could compare noise levels between the two road surfaces.”

Noise testing showed the following results:

  • All the properties named in the designation have road-traffic noise levels below the maximum noise limit specified in the original consent conditions
  • Current traffic noise levels are below those predicted in earlier studies and below the current standards for new projects
  • There was a minor difference between road noise measured on the Bypass surface with the finishing coat of seal and the road surface with an initial coat (0.9 – 1.7 decibels). This slight difference between the two seals will likely reduce over the next few years
  • The properties of those residents not named in the original conditions showed noise levels of between 46 and 61 decibels

Mr  Owen says that while the Transport Agency accepts that the finishing coat of seal may have created a slightly different type of sound, the report clearly shows that traffic noise at the Bypass is within acceptable levels.

“I am confident that we have done our best to keep traffic noise down at the Bypass.  On behalf of the Transport Agency, I thank the community for bringing these concerns to our attention and giving us the chance to investigate them.”

The full Ruby Bay Bypass Road-traffic Noise Assessment Report will be made available on the NZTA website.