The slip-prone Paekakariki Hill Road north of Wellington, damaged again by another bout of heavy rain on Saturday, will be closed for several weeks.
Water running down steep scree-laden gullies above the narrow twisting route undermined the road and led to a washout at the site of previous repairs.
Rubble
from the slip and other debris carried on down the hill and spilled across State Highway 1, closing the key route for some hours.
Kapiti Coast District Council spokesman Tony Cronin said the washout would need extensive work and the road would be closed for several weeks at least.
The hill road leads off SH1 at Paekakariki and runs to Pauatahunui on Porirua Harbour.
The deluge of January last year smashed the road in several places, closing it for six weeks.
Mr Cronin said the council was pleased that on Saturday debris traps in the gullies above the road did their job and caught several hundred cubic metres of scree.
"That scree will have to be removed now but the traps certainly protected the road from further damage."
He noted that though SH1 had to be closed and traffic diverted through Paekakariki township, "at no stage was there any risk to property and the flood management systems and processes all worked well".
The system of scree traps and culverts were built after the January storm.
Mr Cronin said engineers had inspected the washout site to discuss repairs.
Test piles would be driven this week to determine the best option and by week's end the council should be able to say how long the road would remain closed and estimate repair costs.
Every effort would be made to reopen the road as soon as possible.
- NZPA
