Transmission Gully poised for starting pistol

20:22, May 04 2012
Transmission Gully route
The proposed Transmission Gully route.

Finally, almost a century after it was first mooted, the Transmission Gully highway looks set to be built. The $930 million project could be finished by 2021, with a 27-kilometre road cut through the hills from Linden to rejoin State Highway 1 north of Paekakariki.

The New Zealand Transport Agency, which alongside Porirua City Council and Transpower was told yesterday that a board of inquiry had given provisional consent for the road, estimates it will shave 10 minutes off Kapiti peak-hour commuters' trips to and from Wellington.

The highway would be one of New Zealand's biggest infrastructure projects and the Wellington region's biggest roading project since the Wellington motorway extension in the late 1970s.

In its finding, issued yesterday, the board of inquiry said the existing SH1 route through Paremata and Pukerua Bay was inadequate, congested, severed coastal communities and could close in an earthquake or tsunami.

The new route would "rectify those inadequacies by providing a new four-lane route which will avoid congestion, reduce travel times and achieve consistency in travel times".

"The new route will be safer than the coastal route."


However, the decision also listed environmental fallout, including an increase in sediment to Porirua Harbour, destruction of some indigenous growth, and the destruction, modification, or diversion of 10km of streams.

Sediment from construction and the effects on streams, in particular the nationally significant Pauatahanui Inlet, was of paramount importance, the board said.

Just how much sediment could potentially flush into the inlet was a contentious issue and one that experts could not agree on.

Based on additional information, the board concluded that during construction an additional 3024 tonnes of sediment would enter Porirua Harbour, which is between 4 and 5 per cent of the sediment that would flush into it naturally.

There would be about 6 million cubic metres of earthworks, making it the largest earthworks project ever undertaken in the Wellington region.

The draft report says consent should be issued for the main route and Porirua link roads, but it comes with more than 100 pages of conditions.

The final route is yet to be finalised by NZTA.

THOUSANDS of pages of evidence were submitted to the board, which went on numerous site visits in addition to assessing 5000 pages of resource consents and notices of requirement from the applicants.

Earlier this year the board received 70 submissions on the applications – 26 in opposition, 33 in support and the rest either neutral or partly in support or opposition.

Nearly 100 people spoke, including lawyers, experts and homeowners, during a three-week hearing that began in February.

Gully proponents included Kapiti Coast District Council, Greater Wellington regional council and the Historic Places Trust.

The Conservation Department and several affected homeowners opposed the highway.

DOC refused to comment yesterday.

Under new national consenting processes, the Environmental Protection Authority can recommend a board of inquiry assess applications, hear submitters and make a decision on whether projects should go ahead.

The decision is binding and can be appealed against only on points of law. Construction could start in 2015 and be completed by 2021.

The Environmental Protection Authority will publish the panel's final decision in mid-June, after feedback.


An alternative inland route was first suggested in 1919 and has been investigated seriously since the 1980s. In 2010 the Government deemed it a road of national significance, meaning the consent process was fast-tracked and scope for opposition narrowed.

In September last year the environment minister directed that the applications be referred to a board of inquiry. In February and March this year the board of inquiry sat to hear arguments for and against the proposed highway. The Environmental Protection Agency yesterday gave its draft ruling on the highway.


27km - length of highway

4 lanes on the highway

10 minutes time saved by peak-time commuters between Kapiti and Wellington

$930 million NZTA's estimated cost

$58 million for property purchases

627 hectares of land to be retired or planted

13 homes directly in the road's path.


Gully could start by 2015

Gully draft approved

Tramission Gully explained

Video: Transmission Gully flyover

Tranmission Gully in Numbers

The Dominion Post