Extra cold July causes more potholes on Otago roads
One of the coldest Julys in living memory has taken an expensive toll on some Central Otago roads.
Contractors are in overdrive filling in hundreds of potholes that are appearing in the tarseal.
There were 19 consecutive days in July where the temperature was below zero – and on ten of those days the mercury fell to minus six degrees or lower.
The extreme chill caused deep permafrost beneath the road surface.
“When it’s frozen it expands and moves the gravel apart. That's what makes it weak, and then the traffic blows it apart and turns it into a pothole,” says Ian Marshall, Lakes District Roads Manager.
Contractors say Northern Hemisphere roads made of concrete can withstand prolonged freezing, but it costs five times more to make a frost-proof road.
Worst affected is the Crown Range Road between Queenstown and Wanaka, where drivers have to dodge hundreds of potholes.
The permafrost may have thawed, but now heavy rain is threatening to undermine the road again, frustrating contractors who are working long hours to fix the problem.
Motorists are being asked to take extreme care as the potholes can appear within hours.
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