By WAYNE THOMPSON
A soggy clay called Onerahi Chaos may cause a chaotic bottleneck on the Northern Motorway extension during the Christmas holidays.
Just two lanes of the extension to Orewa will open on December 19.
The $228 million project, designed to speed motorway traffic, was meant to open before Christmas, when thousands
of holidaymakers pack up and head north.
But the clay - which turns to mush after rain and cannot be worked by heavy machinery - has become the "Achilles heel" of the project, says Transit project manager Peter Spies.
A soft patch, 250m long, has proved particularly testing for road builders around Lonely Track Rd, where the four-lane motorway cuts through the hills above Albany.
Mr Spies said gullies filled with clay up to 30m deep did not get enough direct sunlight to dry out after heavy rain.
Long delays in waiting for the clay to firm had forced the contractors to order 7000 truckloads of a better-quality fill.
With time running out to meet the opening date, Mr Spies said it was decided to concentrate on building two lanes through the sticky spot, so at least the motorway could be used by traffic travelling in both directions.
There would be a temporary 70 km/h restriction until the remaining two lanes could be completed.
Mr Spies said the big worry now was getting three consecutive dry days so the late stretch could finally be sealed with bitumen.
A 2.2km section of the motorway extension just south of Albany, from Greville Rd to Oteha Valley Rd, has been open to traffic since November 10.
