Slip keeps rocky road shut at night

20:20, Sep 17 2012

A large rockfall near Wanaka is believed to have been caused by an earthquake and has prompted the NZ Transport Agency to close parts of State Highway 6 at night because of the risk to motorists.

NZ Transport Agency Central Otago area manager John Jarvis yesterday said the slip, about 16 kilometres south of Makarora, came down 12 days ago and had continued to deteriorate since.

The slip occurred on September 5 after heavy rain and it was suspected a "very shallow" 5.2 magnitude earthquake two days earlier may have loosened the rock mass above the highway, he said.

"While we have been monitoring this site, it does not have any previous history of slips, which are a constant risk in the area with its steep terrain and high rainfall," he said.

Contractors were working hard to clear debris but heavy rain had exposed further material, making the site dangerous at night. “With the safety of road users our number one priority, the only logical decision was to close this section of highway, between 7pm until 7am, each night until we are confident the slip is safely stabilised," Mr Jarvis said.

The road was open to single-lane traffic during the day but motorists could expect delays while clearance work continued.

It was unknown how long the road would be closed but the contractor was working as quickly as possible to make the section of highway secure, Mr Jarvis said.

che.baker@stl.co.nz

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