Four options for Manawatu Gorge highway


The NZ Transport Agency has released a shortlist of four potential options for a new state highway route to connect the Manawatū, Hawke’s Bay and northern Wairarapa.

State Highway 3 through the Manawatū Gorge has been closed since large slips caused major damage to the road on 24 April 2017 following severe weather.

Geotechnical investigations and long-term monitoring have established that the hillsides in parts of the gorge are highly unstable, and the gorge road is no longer viable as a safe long-term transport route for the region.

The Transport Agency has been working with the community and other key stakeholders in recent weeks to evaluate an initial long-list of 13 alternative options.

“We’ve been gathering valuable feedback on the initial long-list, and we’re pleased to be taking the next step today, with the release of a short list of four options that will be further investigated,” says Ross I’Anson, NZTA Regional Transport System Manager.

“The people of this region need a safe, resilient and reliable transport link between the east and the west of the central North Island.

“It’s essential for the economic wellbeing of New Zealand and our communities, and with the gorge route no longer a safe option we’re working with urgency to make it happen.”

The Transport Agency will be gathering public feedback on the short-list until 25 October, with a preferred approach to be announced in December.

I’Anson says the Transport Agency is encouraging people to provide their ideas and perspectives on the short-listed options.

“We know how important this connection is to local communities, and a very important part of the process is working with our communities to make sure we get the best possible transport solution for the region and the whole of New Zealand.”

Information on costs, length and construction times of the following shortlisted options are approximate:

Option 1: North of Saddle Road

This option would provide a new road corridor across the Ruahine Range north of Saddle Road and the Te Āpiti wind farm.

  • Cost:$350m–$450m
  • Length:7km
  • Time to complete:5–6 years

Option 2: Saddle Road upgrade

This option involves a major upgrade of the existing Saddle Road corridor to bring the route up to state highway standard.

  • Cost:$300m–$400m
  • Length:8km
  • Time to complete:5–6 years

Option 3: South of Saddle Road

This option would provide a new road corridor across the Ruahine Range south of Saddle Road.

  • Cost:$350m–$450m
  • Length:4km
  • Time to complete:5–6 years

Option 4: South of the Gorge

This option is for a new route south of the Manawatū Gorge providing a new road corridor which offers the most direct connection for travel to or from the southwest.

  • Cost:$450m–$550m
  • Length:2km
  • Time to complete:6–7 years

Options dismissed

l’Anson says a number of other options had been ruled out for a variety of reasons:

Option Details Reason for exclusion
Deep Box Cut ·         Cost: $1,900m–$2,500m

·         Length: 12.6km

·         Time to complete: 15+ years

Construction duration, cost, unacceptable impacts on landscape, ecology and sites of cultural significance.
Gorge Viaduct ·         Cost: $1,100m–$1,400m

·         Length: 14.2km

·         Time to complete: 6–7 years

High impacts on landscape, ecology and sites of cultural significance (piles in river would interfere with river flow; substantial ecological habitat loss). High risk of delay due to consenting difficulties. Residual risk of slips in gorge.
Tunnel options
(long tunnel and short tunnel)
·         Cost: $1,700m–$2,200m (long tunnel), $1,200m–$1,500m (short tunnel)

·         Length: 12.7km (long tunnel), 14.1 km (short tunnel)

·         Time to complete: 8-10 years (long tunnel), 6–7 years (short tunnel)

Options do not meet required levels of resilience. Fault lines across long tunnel, risk of slips on short tunnel route.  Large capital and operational costs.
Manawatū Gorge South Bank ·         Cost: $800m–$1,000m

·         Length: 14.3km

·         Time to complete: 8–9 years

Does not meet required level of resilience (numerous high risk slip sites). High impacts on landscape, ecology; unable to avoid known cultural sites of significance.
Various southern options ·         Cost: $550m–$1,250m

·         Length: 14.3km–18.8 km

·         Time to complete: 8–12 years

All options have high construction costs and/or unacceptable delivery timeframes, primarily associated with large amounts of earthworks. Options also impact on windfarms and ecologically sensitive areas.