Repair work needed on Kapiti expressway because waterproof material failed

Tuesday, 25 July 2017

Water penetrating the road surface has led to remedial work being needed on the Kapiti expressway. (File photo)

Water is seeping through the seal on the $630 million Kapiti expressway, meaning it will have to be repaired within months of opening.

The New Zealand Transport Agency confirmed in June that remedial work would be needed to address 'pavement issues' on the 18-kilometre expressway north of Wellington, but was unable to say why.

The 18-kilometre, four-lane Kāpiti expressway opened to traffic in February 2017.

On Tuesday it said tests on road samples had shown the problem appeared to be caused by water seeping through the membrane seal, which is meant to act as a waterproofing layer below the asphalt.

The problem has occurred along just over one kilometre in the southbound lane, and about 260 metres in the northbound lane, in the vicinity of the Kapiti Rd junction.

**READ MORE:

The four-lane first section of the expressway, linking MacKays Crossing and Peka Peka, was opened on February 24. (File photo)

* Repair work confirmed for Kapiti expressway

* ['Pavement issues' on expressway three months after opening

Drivers noticed what appeared to be cracks in the road in June, but the NZTA said the changes to the road surface were not dangerous. (File photo)

*](http://www.stuff.co.nz/motoring/news/93279609/Kapiti-expressway-showing-signs-of-wear-and-tear-just-three-months-after-opening) [Travel times improve, but still worse than before opening

*](http://www.stuff.co.nz/motoring/news/93125020/kapiti-chokepoint-times-improve-but-still-worse-than-before-expressway-opened) [Expressway has made commute 'twice as long'

An open day was held when the expressway was opened. (File photo)

* No quick fix for expressway traffic congestion](http://www.stuff.co.nz/motoring/news/91007617/No-quick-fix-for-traffic-congestion-caused-by-new-Kapiti-expressway-NZTA-says)**

Agency highway manager Chris Hunt said repair work would be done later this year or early next year, though it was unclear what the work would involve, or what it would cost.

'Until we are able to identify what the remedial work will be, we cannot confirm how long it will take. But it is likely that the work will be carried out off-peak and staged to minimise the disruption to motorists.'

The failure of the road's waterproofing materials at the problem areas had led to discoloration and the loosening of fine particles, Hunt said.

While the road would continue to be closely monitored, the issues did not pose any risk to motorists.

The agency used a porous asphalt to cover the road surface, which was considered the most appropriate for the conditions.

'We are still working with our technical experts to find out how water managed to penetrate the seal.'

It was not uncommon for remedial work to be needed on newly-opened highways, but the issues on the expressway were unexpected, Hunt said.

The first section of the expressway was officially opened on February 24.

AA road safety spokesman Dylan Thomsen said the issue was affecting only a small part of the expressway and was not having any impact on motorists.

'Ideally, in any major project, you want to everything to go absolutely perfectly, but that almost never happens.'

Kapiti Mayor K Gurunathan said while the issue was unexpected, he welcomed the NZTA's proactive response.