Quick fix may not stick

A temporary road to replace the closed State Highway 4 could itself be closed at short notice, because the hill it will be built on is still at risk of further slips.

Meanwhile, inappropriate vehicles are causing problems on one of the alternative routes.

The highway between Whanganui and Raetihi has been closed since a large chuck of the road fell away in a slip about 19 kilometres south of Raetihi in early October.

The NZ Transport Agency has been working on creating a temporary road in the meantime.

Agency highways manager Mark Owen told Horizons Regional Council’s regional transport committee yesterday the temporary road would likely be open in early next year.

But being a temporary road on a geotechnically fragile area, the road would be subject to special safety concerns.

The same company doing monitoring work on SH1 near Kaikoura was being employed to put equipment in at the slip site to ensure any movement was detected, Owen said.

Adverse readings or weather events would result in the temporary road being closed.

Investigations were continuing into how to build a permanent road in the area, as well as checks on the resilience of SH4, he said.

The agency wanted to make the entire route more resilient, with the closure a good time to look into it. The temporary routes around the slip include Fields Track and Whangaehu Valley Rd, which are only suitable for light vehicles.