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Drilling starts to remove unstable rock above Homer Tunnel

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The NZ Transport Agency (NZTA) says some long awaited fine weather has seen a start made this week on drilling to remove a 2000 tonne section of unstable rock high above the western entrance of the Homer Tunnel.

Over 80 percent of the rock is not attached to the mountain side and poses such a high risk to road users that it was necessary for the NZTA to close the Milford Road from the eastern tunnel entrance on 23 May 2013, until at least the first section of the rock can be removed.

NZTA Southland Area Manager Peter Robinson says the weather at the site since the road closure has been appalling, severely hampering the efforts of the specialist team to do the work needed to blast the first section of rock free. Up until this week bad weather meant we have only had one full days work on site since the road closed.

“Despite the unremitting bad weather the team have been on stand-by hoping for a fine break so they could get cracking with this important work. The weather finally eased on Wednesday 5 June, allowing the team to begin drilling to prepare the rock for blasting, and was settled enough for a full days drilling yesterday, Thursday 6 June.”

“It is worth noting on a number of the days since the road closure, that the road would have been closed anyway due to the weather at road level and the greatly elevated rock fall risk created by the freeze/thaw conditions at the site.”

It is the expansion of ice forming behind the rock that leads to the freeze/thaw failure mechanism. As a result of these conditions, there is a considerable risk of this rock breaking free and falling to the valley below.

Mr Robinson says because of the way the deterioration of 2,000 tonne section of unstable rock is occurring, if it fails its fall to the valley floor will be rapid. Just to underline the seriousness of the situation, no-one, not even our contractor’s staff, are going through the western portal of the tunnel since the road closed.

“It’s been a huge relief to commence drilling on site and we are counting on brighter weather over the next week to build on this progress.”

We understand the extended road closure is tough on local tour operators and community and appreciate their support, as we do our best to remove this unstable section of rock to give them some certainty around the availability of the road in the months ahead. Mr Robinson said.

The latest information on progress on this rock removal operation is available at www.highwayinfo.govt.nz(external link) or by phoning 0800 444449.

View information about the Milford Road rockfall risk(external link).

You can also sign up for customised State highway travel alerts at www.onthemove.govt.nz(external link).

For more information please contact:

Bob Nettleton
Regional Communications Advisor
T    DDI 03 951 3005   
M   021 954 928   
E-mail bob.nettleton@nzta.govt.nz

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