Corridor speed limit remains
Speed limits on part of Christchurch’s Northern Corridor motorway will not be reduced, despite calls for change from hundreds of affected residents, a local MP and Christchurch City Council.
Redwood residents have been frustrated by noise created from cars on the new $290 million motorway since it opened in December last year.
Some say they are woken as early as 4.30am, while others say it has affected their mental health.
Waka Kotahi NZ Transport Agency (NZTA) said the noise was not excessive and would be addressed once ‘‘low noise asphalt’’ was added to the motorway in October.
But some of Christchurch’s elected officials wanted something done in the meantime.
Both Christchurch Central Labour MP Duncan Webb and the city council asked NZTA in April for a temporary speed limit reduction to help address noise concerns.
NZTA ruled out any changes in a reply to Webb last week.
Regional relationships director Ian Duncan told Webb further noise mitigations were not under consideration.
Duncan was satisfied with the mitigation measures already in place, which included bunds, wooden fences and concrete barriers on parts on the motorway.
Duncan said NZTA could only legally lower the speed limit in the short term for road safety reasons. Any other changes would require consultation and a legal process ‘‘that normally take[s] longer than just a few months’’.
‘‘We are balancing that mandatory legal process against good evidence that a change in speed will not lower the noise level enough to be significant to local residents,’’ he said.
Webb said he was disappointed NZTA would not address the noise before adding the next layer of asphalt.
‘‘I would still like to see improvements for the residents, and we will be considering how best to try and achieve that.’’
Webb said he appreciated changing speed limits would take time, but he wanted to know whether the Redwood community was consulted on the current speed limit.
Peer-reviewed noise testing of the motorway by Marshall Day Acoustics showed in some sections, the noise was above the appropriate standard for motorway noise by about two decibels (dB). NZTA said the noise difference was too minimal to be noticed.
The testing happened between 10am and 3pm, but was then averaged over the full day with allowances for peak time traffic. The peak times were 6.45am to 8.30am, 3pm to
4pm, and 5pm to 6pm, NZTA said.
The agency was conducting further noise testing over a full
24-hour period, following requests by residents.
NZTA expected the final layer of asphalt to reduce noise from the motorway by about five to seven dB.