The NZ Transport Agency is advising motorists that the Manawatu Gorge will be closed until further notice as rising river levels have caused significant erosion which has severely damaged the temporary road through the gorge, making it unusable for vehicles.
NZTA Palmerston North state highways manager David McGonigal says the route was closed to traffic late last night (July 5) after river levels rose to nearly 7 metres higher than normal, eroding the slope and washing away the slip material which helped to support the temporary road.
"While we're disappointed that motorists and local residents will again face the inconvenience of a closure, the good news is that the safety systems which we had in place to monitor the river and the temporary road have worked and the road was closed before anyone was put at risk.
"We always anticipated the potential for flooding to cause problems, which is why we shifted the temporary road further inland and away from the river last week. Unfortunately Mother Nature has thrown us another curve ball and the intensity of the flooding in the river has simply eaten away so much of the slope that we've lost a good chunk of the temporary road as well."
Mr McGonigal said the level of damage meant it was unlikely the temporary road would be rebuilt, and the agency would instead focus all of its efforts on accelerating the construction of bridges to replace those destroyed by last year's slip.
He says that despite recent bad weather, progress on the bridges is still going strong, with work continuing installing bridge piles, and half of the bridge abutments now installed.
"The bridge crews will be working as quickly as possible, and once one side of the bridges is complete we'll be able to re-open a route through the gorge. In the meantime, while the closure is in place motorists will need to revert to using the alternative route."
Electronic information signs will communicate the closure information to motorists, and motorists are asked to observe the signs at all times.
Mr McGonigal said the agency would be in a position to provide an updated timeframe for completing the bridge work by the middle of next week, but on current estimates the work was expected to take between four to six weeks to complete.
"We understand this isn't the news that anyone wants, and we'll be working overtime to get this work complete and get the road opened again. We know that this will cause delays for drivers and further disruption for people in Ashurst and Woodville, and we're very thankful for the ongoing patience and understanding that everyone has shown over the past several months."