Waikato roads deliver bumpy ride after summer shrinks peat soils

The most affected roads include Rukuhia, Collins and O'Regan roads in Rukuhia, and Storey and Cambridge roads between Te Awamutu and Cambridge. Photo / Supplied

Waipā District Council says drivers might find some roads bumpier this winter - a result of extremely dry weather across the country.

An unusually dry summer and autumn has resulted in shrinkage of peat soils on which several roads in Waipā are built.

The shrinkage is causing surfaces to settle unevenly, creating bumps, cracks and ruts in the road.

The areas most affected include Rukuhia, Collins and O'Regan roads in Rukuhia, and Storey and Cambridge roads between Te Awamutu and Cambridge.

However, other roads around the district are also occasionally affected.

Waipā District Council transportation manager Bryan Hudson said it was a common problem around the Waikato region, which contains about half of New Zealand's peatland.

"Many roads in the Waikato are built on top of peat soils. These soils are very deep in the earth, so excavating them and building a normal road foundation would be extremely costly.

"Instead, we manage the situation by allowing for the reshaping of the surface of peat roads every five to 20 years, but exceptionally dry years mean more repair work.

"This year, because of the weather, the issue is more pronounced."

Hudson said the council was closely monitoring the roads and would intervene where required to erect warning signs and speed restrictions or to smooth the surface with asphalt.

"Drivers will see signs and speed restrictions in place on Storey and Cambridge roads already. Others may be required soon as the peat soils continue to shrink for some months until normal moisture levels return.

"Drivers also need to be aware temporary repairs may be required, which could cause some delays."

If implemented, some speed restrictions could be in place until September or October.

Hudson said road users needed to be vigilant on all roads, report any issues and drive to the conditions over the winter.