Steel net to stop rocks
A 1600 square metre steel net will be anchored into a section of the Mangaotaki Bluffs above State Highway 3 near Pio Pio to prevent rock falls like the one that struck and killed passing motorist Joy Thompson in March.
The $2.5 million safety project will start next Monday.
The Transport Agency announcement comes after the Waikato Times reported that state highway bureaucrats were repeatedly told that rockfalls posed "a significant hazard to motorists".
Major engineering works were never carried out to remedy the problem.
Instead, standard maintenance, emergency responses and minor risk-reduction operations were done, including a $45,000 contract that was scheduled to begin three days after the lethal incident on March 28.
The revelations were exposed in Transport Agency documents released to the Waikato Times under the Official Information Act.
They stretched back to 2000 and show engineering contractors were "certain" rocks would continue to fall onto State Highway 3 and potentially strike vehicles long before Thompson, 74, was killed beneath the southern Mangaotaki Bluffs.
The rock that struck her and her sister hit with such force that it stoved in the passenger side and spun the car 180 degrees on to the opposite side of the road.
The major project is expected to be complete by early December, NZ Transport Agency's regional performance manager Karen Boyt said.
The stretch of highway had been down to one lane with a temporary barrier to contain falling rocks since March.
Current stop/go traffic management will remain in place while contractors complete the work.
Boyt said the steel net was a long term solution to rock stability at the site."
Geotechnical specialists worked their way through a detailed inspection and rock scaling process earlier this year to gain a better understanding of what work was needed to stabilise the cliff face," she said.
"Since then we have removed larger rocks by blasting at the site but our investigations show that the steel net is the best long-term safety solution."
Boyt said a crew of abseilers would begin the project by clearing loose material off the rockface from Monday.
However the majority of work to anchor the net would be completed using drill rigs attached to two cranes.
"When the project is complete, the steel net will be secured to the bluff by 500 anchors, which will dramatically reduce the risk and impact of rock falls in the future.''