Power cuts nearly led to closure

The AA says scrimping on the back-up generators for the Northern Gateway is a bizarre decision. Photo / Glenn Jeffrey

Auckland's Northern Gateway toll road lacks back-up generators to keep its tunnels open during long electricity cuts, an omission which the Automobile Association calls bizarre.

Although battery packs give two hours of emergency power, the Transport Agency said yesterday that it came within about 30 minutes of shutting the tunnels during widespread electricity cuts in Auckland and Northland at the end of October.

That would have also meant a full closure of the 7km toll road between Orewa and Puhoi, which opened almost a year ago after costing the agency $356 million to build.

Regional highways manager Tommy Parker said electricity substations from the national power grid normally fed supply to both ends of the twin tunnels through Johnstones Hill at the north of the toll road.

He said electricity cuts on October 30 were highly unusual in causing a loss of supply from both sources, leaving the agency within half an hour of closing the tunnels on safety grounds, given that power is needed for their fire sprinkler systems as well as surveillance cameras and lighting.

"We are not prepared to run the tunnels without the fire safety system," Mr Parker said.

The cuts followed damage to national grid operator Transpower's 220,000-volt Henderson-Otahuhu line, disconnecting 280,000 homes and businesses across North Shore City, Rodney District and Northland.

Transpower remains five years away from building a second high-voltage transmission line to Northland that would prevent a repeat strike.

But Mr Parker said the Transport Agency was confident after reviewing the incident that the chances of a recurrence were low, and that back-up power generators were not needed.

"With the two sources of power provided, we're comfortable that we're suitably covered," he said.

Automobile Association spokesman Simon Lambourne did not share his confidence, saying it was bizarre the agency would have spent so much building such "a great piece of transport infrastructure" without installing back-up generators.

"It is State Highway 1 and a very important national road that they have spent hundreds of millions of dollars on, and I don't think it's an unreasonable expectation that there is a back-up power supply," Mr Lambourne said.

"Hospitals have back-up generators and lots of organisations do in case there is a power failure - heaven forbid if we have a civil emergency and the power's out."

Mr Parker said motorists always had the alternative of driving along the Hibiscus Coast Highway between Orewa and Puhoi, the main route to Northland before the toll road opened last year.

But Mr Lambourne said it was ridiculous to rely on that route, rather than spend "a very small amount" on generators.

He said that and a similar "scrimping" exercise in not providing enough toll payment kiosks on each approach to the road risked tarnishing its public image.

He added that the AA was also annoyed that motorists were required to pay to use the toll road after being diverted by police from the free Hibiscus Coast road, following two serious crashes in the past year.

He said a legislative condition of being allowed to build any toll road was that a free alternative route be provided.

Mr Lambourne said the Transport Agency should have shut down the tolling machinery for the duration of the closure.

But Mr Parker said the agency could not offer "short windows of non-payment" on the toll road, and rebating those who had already pre-paid for their travel would be too difficult.