$28m plan to replace Gates of Haast bridge

The single-lane bridge on State Highway 6 at the Gates of Haast appears likely to be replaced with a sweeping two-lane bridge on a realigned approach, at an estimated cost of $28 million.

Before it goes ahead, the New Zealand Transport Agency needs to exclude about 1.2ha from the Mt Aspiring National Park, requiring a land swap with the Department of Conservation.

That requires the consent of the Otago Conservation Board, which will consider the land swap today at its meeting in Berwick.

If the board agrees, it will receive about 4920sq m of redundant road reserve.

NZTA project manager Chris Collins said this week there had been no adverse submissions to the proposal, which was advertised in October 2008.

The NZTA had been working since then on land-swap and designation issues.

An NZTA study in 2006 came up with six options addressing road safety, travel efficiency and maintenance costs.

Threats to the bridge include landslip movement, floods, and heavy vehicles colliding with the bridge.

It was built in 1962 and is regarded as a vital commercial, social and tourist link between Westland and Otago.

Of the six options, the road realignment and new bridge was considered the most feasible to bypass the slip and erosion area.

Mr Collins said there would not be a viewing platform, but there would be a footpath along the upstream side of the new bridge.

The car park area uphill from the bridge would be formalised and the car park on the downhill side would be removed because of an active slip at that site.

Department of Conservation West Coast community relations officer Fiona Pollard said this week a clause would be inserted in the Reserves and Other Lands Disposal Bill if the board agreed to the proposal.

The land exchange would be part of a compensation package, and any land received by Doc would be added to the national park, she said.

Mr Collins said the agency's three-year national transport plan provided for a design phase in 2011-12 but it could take a long time to complete the design and land-swap phases. A construction date has not been set and the $28 million budget was not fully realised.

The Gates of Haast bridge is about 60km east of Haast and 86km west of Wanaka.

It is on a popular tourist route and motorists often stop at the bridge to take photographs.

A recent crash history was not available, but the NZTA considers the potential for accidents is high.