Mayors fear crumbling bridges could leave rural families stranded

Councils fear hundreds of crumbling bridges around the country may leave rural families and businesses stranded, unless the NZ Transport Agency commits to helping fund replacements.

The Lower Kohuratahi Road Bridge in East Taranaki and Lower Valley Bridge in South Wairarapa are just two structures operating under weight restrictions, after recent surveys found they were beginning to fail.

Stratford District Council is responsible for about 150 bridges, some of which service just one or two properties at the end of rural roads.

Built in 1938, the historic Lower Kohuratahi Bridge is a 50-metre-long wooden suspension bridge. It was closed in September, after engineers found it at risk of structural failure.

Mayor Neil Volzke said its problems were symptomatic of a wider problem.

"Across our district and across many rural districts in New Zealand, there are lots of bridges that are in that 100-year-old age bracket and some of them older. A lot of them are falling due for replacement."

One family lives beyond the Lower Kohuratahi Bridge and beekeepers use it for access to their hives. It had since been re-opened with a 400kg weight limit.

Volzke feared NZTA wouldn't contribute to a replacement likely to cost about $1 million.

"Normally, a bridge replacement would attract some subsidy or funding from NZTA, but they do have the ability to declare a bridge as uneconomic, in which case they can withdraw any funding that might have been there.

"If that happens, then of course the cost of replacement, if we choose to go ahead, falls entirely on the council."

At the recent Local Government NZ conference, Stratford had a remit adopted, calling for NZTA to commit to co-funding uneconomic infrastructure, or for government to provide clearer guidance about downgrading or ceasing to service low-traffic areas.

South Wairarapa Mayor Fran Wilde was familiar with the looming problem.

"We've got about 140-odd bridges and large culverts, and frankly, we can't afford the maintenance on these.

"Some of them are significant in terms of getting heavy traffic in and out of the district, but some of the bridges might only go to one or two farms."

Wilde said issues had recently been identified with the about 100-year-old Lower Valley Bridge on Kahutrara Road, which was often used as a detour, when State Highway 53 floods.

"What has happened in the past is that, when the Waihenga Bridge has been closed, the traffic has been diverted through the Lower Valley Bridge, which is a little further away and a smaller bridge.

"We are now having all our bridges surveyed and we've just had a review of that [the Lower Valley Bridge]. They have said, 'Oops, it can't stand up to the heavy traffic it's getting', and we're having to now close it to some heavy traffic."

Now, every time the Waihenga Bridge is closed, the Lower Valley Bridge is also shut.

An engineer's report has suggested a range of options for the Lower Valley Bridge, from a band-aid repair costing about $370,000 to full replacement at $20 million.

Wilde said South Wairarapa could not afford a new bridge without NZTA assistance.

The Transport Agency acknowledged the financial burden councils currently faced and said it worked closely with all local authorities to best share that load.

"We appreciate the difficulty in funding uneconomic transport infrastructure in rural areas and we're aware of the remit that has been presented to Local Government NZ."

NZTA said current funding was guided by the Government Policy Statement on land transport, which identified value for money as a strategic priority.

It also had an Uneconomic Transport Infrastructure Policy, which involved a series of steps to help determine whether or not a proposed investment was efficient, and to identify what other sources of funding might be available.

"If the decision is to decline funding out of the National Land Transport Fund, a council can consider other funding sources for uneconomic transport infrastructure."

The Transport Agency said it applied a Funding Assistance Rate for regular investment in transport activities of councils and other approved organisations.

FARs, which could be applied to regular maintenance of bridges for example, were set out every three years and averaged about 53 percent currently.

"Where transport infrastructure was damaged due to an emergency event [like storms and earthquakes], there was a higher level of assistance for emergency works [normal Funding Assistance Rate, plus 20 percent]."

The Land Transport Management Act did not require emergency response work to be efficient.

"However, the recovery work for infrastructure that repeatedly gets damaged by weather or other events usually requires some consideration of options, including community managed retreat, lower levels of service, maintaining current levels of service or improving resilience."