Potholes new threat as water clears
Potholes are appearing around Canterbury after two months’ worth of rain fell in 48 hours on Friday and Saturday, causing widespread flooding.
Roads were still closed across Christchurch and a state of emergency remained in place yesterday, although rivers were returning to their normal flow.
In a statement, the Christchurch Transport Operations Centre (CTOC) said potholes had appeared around the city due to water sitting on roads.
‘‘Contractors are in the process of clean-up operations.’’
The New Zealand Transport Agency (NZTA) said potholes formed when water got into cracks in the road.
‘‘Vehicles drive over the cracks moving the water around and putting it under pressure. This movement and pressure opens up the cracks which eventually form potholes,’’ a spokeswoman said.
Potholes also formed when water froze and expanded in cracks.
‘‘When the road thaws the cracks are bigger, which allows more water in and the cycle repeats itself until a pothole is formed.’’
Potholes could only be fixed temporarily in winter conditions, with permanent repairs having to wait until spring and summer.
AA mechanical advice spokesman Philip Collings said potholes could be deeper than they looked.
Deep holes could put out a car’s wheel alignment, puncture tyres and damage rims, he said.
‘‘These types can potentially be quite hard on the car.
‘‘The slower you go, potentially the less damage you’re going to do, but that’s not practical.
‘‘We would say to people just be vigilant of these potholes and try and avoid them if you can – otherwise damage can result and it could be expensive.’’
A Christchurch City Council spokeswoman said the council dealt with about 22,000 potholes a year, each costing an average of $30 to fix.
More than 25 roads remained closed in central Christchurch early yesterday, most near the Heathcote River.
Many had since reopened, including Dyers Pass Rd between the Sign of the Takahe and Governors Bay.
Rapaki Track remained closed because of a slip and many Port Hills cycling tracks were closed.
In the Ashburton district, a section of Thompsons Track remained closed because of flooding. Detours were in place between Line and Winchmore Lauriston roads. Most other flood-affected roads had reopened.
‘‘Potholes and washouts are now a hazard on some roads following the flooding and council is urging drivers be mindful of this damage and to drive to the conditions,’’ a statement from the Ashburton District Council said.
Christchurch residents whose properties were flooded above floor level were advised to stay away from home.
The council has identified 30 properties as having flooded above floor level, with another 27 flooded above foundation level.
Canterbury medical officer of health Dr Alistair Humphrey said there were ‘‘significant health and safety risks’’ associated with living in badly flooded properties, especially for children.
He said carpet and other soft furnishings were likely to be contaminated by sewage, mould was likely to worsen until houses were properly treated and wiring needed to be checked by a qualified electrician before people moved back into their homes. ‘‘I strongly advise anyone still living in a property that has been flooded above floor level to stay out of the property until it has been properly checked and deemed safe to live in.
‘‘Anyone already experiencing health problems should contact their GP for advice.’’