Warkworth's maddening turnoff to eastern beaches will be worsened by a $760 million motorway extension past the town, a retired senior engineer warned a board of inquiry yesterday.

Roger Williams, a former civil design manager for the Opus International consultancy who has retired to Warkworth, testified that minor interim improvements which Transport Agency says it will make to the Hill St intersection ahead of the 18.5-kilometre motorway extension will be overwhelmed by traffic growth in the meantime.

The agency's northern highways manager, Tommy Parker, acknowledged to the board on Tuesday that the site was "essentially three intersections squeezed into one" but said an upgrade had to be delayed until after the motorway project so that long-distance traffic could be diverted away from it first.

His organisation is seeking approval to extend the motorway as a Road of National Significance from the Johnstones Hill traffic tunnels south of Puhoi to a new roundabout two kilometres north of Warkworth.


But Mr Williams said the agency's projections showed the existing State Highway One would still carry more traffic than the new motorway, which is likely to be tolled.
They predict 14,500 vehicles a day will still be travelling on SHI in 2026 - about the same as now - compared with 14,000 expected to use the motorway.

He said pressure on the Hill St intersection would be increased by extra traffic from Warkworth and the eastern beaches having to head north through it, to reach the new motorway, which the agency hopes to complete by about 2021.

Difficult right-hand turns from the east, into the existing main road north, would become even harder and "the intersection will not cope," he told the five-member board chaired by retired High Court judge John Priestley, QC.

Only a major upgrade - either entailing bringing Warkworth's main Elizabeth St directly into the intersection as proposed in 2009 by the agency or a radical new design he has prepared - would allow it to keep functioning in the meantime.

"I believe there are no minor tweaks - forget it."

Mr Parker said earlier that a major intersection upgrade now would cause "chaos" to traffic passing through Warkworth over two summers, but has proposed widening three approaches to it in the meantime.

He said Mr Williams' design would mean an incursion into Kowhai Park, which he believed would be opposed by many local residents.

But Mr Williams said the Rodney Local Board backed his proposal, which could be built largely off the existing SH1, in less than a year.

He also wants the Transport Agency to build a motorway interchange south of Warkworth, so drivers heading to or from the town will not have to loop around the north.
The only interchange the agency proposes between Orewa and Warkworth is at Puhoi, where it plans south-facing ramps only.

Heavy Haulage Association chief Jonathan Thomson asked the board to require the agency to add north-facing ramps to allow trucks carrying over-size loads to join the motorway from the Hibiscus Coast Highway, to which they are now restricted by being barred from the Johnstones Hill tunnels.

The association also wants the motorway built wider than proposed, to cope with over-size loads he said were become more common because of a trend toward pre-fabricated construction.