Heavy rain and high traffic volumes are to blame for the pothole which punctured tyres on at least 30 vehicles on State Highway 1 south of Whangarei.

The pothole developed on a bridge north of Kaiwaka last Thursday.

The first of the unsuspecting vehicles hit the pothole around midday. Some vehicles suffered one puncture, while others had both the front and rear tyres on the passenger's side ruined.

New Zealand Transport Agency Northland highway manager Brett Gliddon said the routine maintenance crew patched a few small holes at the same location the day before the pothole appeared.


"Heavy rain and high traffic volumes mean the road surface deteriorated quickly on Thursday morning."

He said NZTA was notified about the pothole at 1pm on Thursday and had it fixed within an hour.

Mr Gliddon said patching potholes is a temporary repair using a 'pre-mix cold asphalt material'.

"Unfortunately, at some locations, and this one is included, they can give way again after heavy rain and where there's high traffic volumes."

He said although it was impossible to predict exactly where potholes were going to occur and how significant they might be, contractors responded as quickly as possible once they were identified.

In winter months, a slightly longer-lasting repair involving heavier equipment and hot asphalt was used, which involved additional planning, closing a lane and working at night.

This was still a temporary repair until permanent repairs could be done during the drier, warmer, summer season, Mr Gliddon said. This offending pothole would be monitored until a permanent repair could be done.

Mr Gliddon said last Thursday that the NZTA would consider the individual circumstances for each case before making a decision about compensation.

Kerikeri man Mike Isle had his two front tyres replaced last Tuesday because the tread was running low. Two days later as he headed to Auckland he hit the pothole and one of his new tyres - along with an older one - "shredded".

He said his rims were also damaged.

"Within 10 minutes, that one sinkhole took out no fewer than 24 vehicles with multiple punctures and wrecked wheels."

Mr Isle said an AA road serviceman helped as many as he could.

"He put spares on all the cars he could, making no distinction between AA members and non-members, and those with single punctures could at least move off."

NZTA is still working to confirm if it has received any requests to pay for damage.