The investigation, design and consenting phases for the rock face works have taken longer than expected. This has been due to the need to find a design that ensures the highway remains open to traffic during construction and is appropriate for the challenging ground conditions and the surrounding environment.
The agency's highways manager, Brett Gliddon, said the original plan was to widen the road away from the rock face, and provide rockfall protection with a catch fence. However, investigations concluded this would require closing the road for several weeks - causing significant issues for the local community and motorists.
Instead the agency will keep the road in its current location and use wire mesh to protect the rock face.
"To stop any further rock falls a 400m steel mesh will be constructed to cover the entire cliff face. The mesh is similar to that used successfully along State Highway 36 in the Mangorewa Gorge between Rotorua and Tauranga."
The work is estimated to cost $1.7 million for the mesh bolting and road repairs.
A single lane will remain in place and will continue to be controlled by traffic lights throughout the repairs.
"We appreciate that there has been a considerable delay in getting the road fully open and want to express our thanks to local residents, drivers and the community for their patience while a suitable solution was identified to minimise any further disruption to motorists who use this road."
The agency's website is regularly updated with information about most closures and detours at www.nzta.govt.nz/traffic.
