Gorge still extremely unstable
New cracks in an area of rock face through the Manawatu¯ Gorge show it is still highly unstable and too risky to allow workers in.
Dozens of slips have come down on State Highway 3 through the gorge since it closed in April last year, including slips on both sides of Kerry’s Wall – an area identified as the site of a potential mass landslide – near the Ashhurst end.
The NZ Transport Agency has predicted as much as 630,000 cubic metres of material could drop at that site.
Transport agency regional transport systems manager Ross I’anson said even more significant than the slips were the cracks that have formed above Kerry’s Wall, caused by movement of the rock face.
‘‘The continued instability of the rock face means that the risk level at this site remains extreme.
‘‘The signs of failure show that the movement of the hillside is continuing, confirming that the area is highly unstable.’’
The transport agency predicts the rock face will drop in four stages, but I’anson said it was not possible to predict when it could come down.
‘‘The area remains unsafe for workers to access. We will continue to monitor the site.’’
A slip of 630,000cum would be 170 times larger than the two slips that caused the state highway to close indefinitely.
There were also a few minor slips in other parts of the gorge in February, I’anson said.
The main link between Manawatu¯ and Hawke’s Bay remains closed and a permanent alternative route won’t be complete for at least five years.
For now, people must take the Pahiatua Track or Saddle Rd, which are both windier and longer.
The announcement on a preferred alternative route is expected by the end of March. The four possibilities for the new road are an upgrade to the Saddle Rd, a new road north of the Saddle Rd, a new road south of it, and a new road south of the Manawatu¯ Gorge.