A $3.5million project to stabilise a rock face which closed a section of State Highway 30 between Rotorua and Whakatane last year is expected to get underway next month.

SH30 was closed after a series of large rock fell from the rock face and blocked the road.

Wire mesh to be used to stabilise the rock face above SH30 at Ruato Bay.

The cliff face will have a steel mesh placed over it which will secure the area and prevent further rock falls over the 400m site at Ruato Bay, says the NZTA.

Acting state highways manager Andrew Scott says the work involves drilling and bolting the rock columns together, and then covering the 400 metre long face with a steel wire mesh.

'The wire mesh is similar to that used successfully along State Highway 36 in the Mangorewa Gorge between Rotorua and Tauranga.”

He says workers are expected to be on site from late July – a contractor to undertake the project will be appointed by NZTA's project partner, Rotorua District Council, in the coming month.

'We appreciate there has been a considerable delay in getting the road fully open, but our initial investigations found significant instability in the rock face that posed a serious risks for road users.

'A suitable solution had to be worked through and the required consultation with directly affected stakeholders and consents obtained.”

He says the wire mesh solution was not the preferred option, but required to minimise any further impact to motorists.

'Our initial plan was to widen the road so there would be sufficient room along the shoulder of the road where rock fall material could be captured away from traffic; investigations concluded this would require fully closing the road for several weeks causing significant issues for motorists, which was not a suitable option for us.”

Andrew says the construction work can be done within a short time frame and should be completed by September with the road expected to be fully open once it is finished.

A single lane will remain open and will be controlled by traffic lights while repairs are undertaken.

The cost of this project is roughly $3.5million which includes the emergency response that saw workers remove trees and hand scale the rock face so the road could be reopened to a single lane.

A concrete barrier which was placed along the bottom of the cliff face to provide protection for drivers will remain throughout the repairs.

Andrew says during the initial emergency response the rock face was found to be highly unstable and further investigation was needed before any work could start to stabilise it.

'Some of the challenges we identified included the height, angle and shape of the rock face, compiled by the fact that there are restrictions due to the width of the road and the area also contained items of cultural and historical significance.

'We want to express our thanks to local residents, drivers and the community for their patience while we worked through the investigation and while we undertake these repairs.”