Potholes in two-week-old Waikato expressway

A stretch of new roadway north of Meremere gets a patch-up after chunks of it started breaking up. Picture / Paul Estcourt

An outbreak of potholes on the approach to the new Mercer-to-Longswamp expressway section is causing problems for Transit NZ.

The holes in a 40m stretch of State Highway One north of Mercer have been blamed for causing several flat tyres on Sunday.

They have since been filled in, but Transit says it needs several days of clear weather before deciding whether more permanent repairs are needed.

That may mean roadworks and a speed restriction when the new road construction season starts in about October.

Transit said yesterday that wet weather had accelerated a breakdown of the surface between old and new paving, which had already been under stress from heavy construction traffic involved in building the $83.5 million expressway section.

Motorists have enjoyed the removal of speed restrictions since Transport Minister Annette King opened the 12km dual carriageway almost a fortnight ago.

But a Herald reader said a tyre on a car in which she was travelling between Auckland and Hamilton on Sunday afternoon ruptured after hitting a series of large potholes in the left southbound lane several hundred metres north of Mercer.

Colleen Mellsop said several other motorists appeared to have hit the same holes, as they were changing tyres on the side of the road in wet and windy weather.

She said police turned up later to slow traffic, and a Mercer resident said a mobile trailer with flashing lights was moved into position to funnel vehicles into the remaining southbound lane.

The Bombay to Mercer section of the Waikato Expressway was built in 1998.

Transit regional operations manager Kaye Clark said there had been some settlement of underlying swampy ground and the road had taken a pounding from construction traffic.

That had been exacerbated by the recent wet weather.

The holes north of Mercer had been filled in when a Herald photographer visited the scene yesterday afternoon, but a maintenance crew was working on a the new highway at the northern end of the Meremere straight.

Its outside edge - including a piece several metres long - was breaking up, and the left lane was closed to traffic.

Ms Clark said verges of new road were sometimes vulnerable to heavy traffic before stabilising vegetation had a chance to grow.

Transit is also planning repairs to patches of the expressway's northbound lanes south of Mercer where they traverse the old road which has erosion problems.

"It's a bit sad, because we've got a nice bit of new road but some tidying up to do on both sides," Ms Clark said.

Traffic will remain under an 80kph speed restriction in the meantime on that section.

* Transit, Land Transport NZ and the police have announced plans to increase traffic enforcement and make improvements to a 17.5km stretch of State Highway 27 in the Hauraki district.

The stretch between Mangatarata and Patetonga, has had four fatal crashes since 2001 and is one of 10 black zones in Waikato and the Bay of Plenty targeted for safety improvement this year