Ruts in the road on two sections of the Waikato Expressway
Thursday, 26 October 2017
Two sections of the newly built Waikato Expressway are failing and it may be because the approved designs were novel and untested.
Visible ruts are developing in two sections of the Waikato Expressway, most noticeably in the busier slow lanes, the NZ Transport Agency says.
Monitoring of the multimillion-dollar Ngāruawāhia and Te Rapa expressway sections revealed the problem and analysis next month will determine what repair work is needed and the cost.
In the meantime, the ruts pose no safety risk, NZTA says.
**READ MORE:
* Repair work needed on Kapiti expressway because waterproof material failed
* Contract awarded for Hamilton section of the Waikato Expressway**
* New road to bring 300 jobs, 1 bridge
* Road bosses fail to fix road where three people died**
The agency raised concerns about the novel road surface design - and received expert assurance - before the roads were built. It now expects its suppliers to help with the fix.
But until testing is done next month, the NZ Transport Agency says no one knows what repair work is needed or how much it will cost.
The agency raised concerns about the novel road surface design - and received expert assurance - before the roads were built. It now expects its suppliers to help with the fix.
There is no safety risk to drivers, a statement from NZTA senior manager of project delivery, Chris Hunt, says.
The ruts appear as very slight dips in the road, Hunt says, and aren't usually noticeable to the untrained eye.
They are mainly forming in the wheel tracks.
However, if there are problems with one of the successive layers of materials making up the road, it could result in things like visible ruts.
The problem came up during an NZTA update to Hamilton City Council and caught Councillor Garry Mallett's attention.
At the Tuesday meeting, he quizzed NZTA spokesman Peter Simcock on how it happened on a 'flagship project'.
Ruts in the two expressway sections started appearing fairly soon after they opened, Simcock said.
'On those two projects, we probably allowed designs that were untested. And we have learned from those two. For the Huntly and Hamilton sections, we've put a lot more specification into the contracts,' he said.
'We did identify some issues with the designs when we evaluated tenders for the Ngāruawāhia section. In fact, we had three bids and all three designs raised concerns for us.
'While we did challenge the designs at the time of the tender evaluation and when we awarded the contracts, we received all the assurances from their experts - and they were recognised pavement experts - that they would perform.'
Mallett wasn't convinced.
'Is that the right way to do it? On a flagship project like that, should you be testing things out?'
NZTA should be looking for new solutions, Simcock said, and the contract model favours innovation.
In the Te Rapa and Ngāruawāhia cases, it led to carriageways that were relatively inexpensive to build, but which cost more to maintain.
Public money might have to pay for some of the rut repairs, but NZTA expects suppliers to address the problems.
The experience also informed what NZTA did for the Huntly and Hamilton sections, Simcock said.
'We will be getting pavements that we know will work, so we're paying more for those.'
Firms involved in the design and construction who were contacted referred questions to NZTA, citing the terms of their contracts.
Hunt was unavailable for comment, but said in a statement that the ruts were picked up through monitoring.
'The visible rutting which has developed on the Te Rapa and Ngaruawahia sections of the Waikato Expressway is occurring at several points along each section (not along the entire length), most noticeably in the slow lanes which carry more traffic.'
They aren't a safety risk, the statement said, but NZTA needs to find out what is causing them.
'We'll be carrying out onsite testing next month to identify the cause. Until we've done that testing, it's too early to say what remedial work may be required or how much it will cost.'
Meanwhile, work is progressing on the Hamilton section of the expressway, but progress was held up by a wet summer last construction season.
'We have saturated ground conditions and standing water and this now is slowing the start-up of this construction season,' Simcock told Hamilton City councillors.
'We're still aiming for completion in 2020, although another wet summer could certainly put that at risk.'
Bridges are due to open throughout the expressway section over the next 12 months, including one on State Highway 26 or Morrinsville Road in November, and a Gordonton Road bridge in December.