More than $100 million has been incurred by local authorities and road users due to closures in the Manawatu Gorge, according to a logistics expert who says a long-term solution could take up to a decade.

Corporate Logistics' Gincarlo Hannan has released his report, The Achilles Heel of State Highway 3, which raises questions about the time taken to explore a permanent solution.
Mr Hannan describes the road as a short but critical link which has been closed for more than 550 days since 2004.

He says it has taken the Government more than 13 years to "seriously" consider alternative routes and, in the meantime, road users and the NZ Transport Agency had incurred millions of dollars in costs.

The report states Corporate Logistics has calculated the daily loss to the region's economy to be $100,000, equating to more than $55 million in the last 13 years.

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"The Government spends millions nationwide improving and reducing the length of freight connections. Adding a further needless 5km onto the freight passageway between Manawatu and Hawke's Bay does not make sense."

Mr Hannan said one of the main contributors to the unstable rockface along this East-west corridor was road widening and straightening initiatives, occurring between 1920 and 1940, and 1960 and 1980.

"Each period has preceded a new era in slope instability. The cause of repeated slope failure of State Highway 3 through the Manawatu Gorge is well known by geologists and geotechnical slope engineers.

"By far the greatest cause of slope instability is directly attributable to the continual road widening and straightening since the road's inception in 1872."

His report explores four options put forward in a 2012 report commissioned by NZTA.
Alternative routes include a multi-lane, direct line through the Tararua Ranges costing $309 million. Mr Hannan says this option appears feasible and is used in other parts of the world.

The second option is a bridge and viaduct to follow the corridor of the existing road, costing $412 million. Mr Hannan says this is a good idea to draw tourists in but warns designers will need to consider any risk of slope failure.

The third option is for a route along Worley Road, north of the Manawatu Gorge. At $118 million and although the cheapest, Mr Hannan says this the least desirable in terms of logistics.

"The Government spends millions nationwide improving and reducing the length of freight connections. Adding a further needless 5km onto the freight passageway between Manawatu and Hawke's Bay does not make sense."

The final option is a tunnel costing $1.8 billion which Mr Hannan says would need to cross two major faults. But the 2012 report suggests a long-term solution will be at least a decade away.

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NZTA is working closely with local councils on a detailed case. At the end of July, Transport Minister Simon Bridges visited the area promising residents a tender process was underway, and the preferred option was likely to be announced in December.

NZTA will then complete the design and consenting work but Mr Bridges warned it would take a lot of time.