We can save $600k, says bridge group

Wakefield St bridge in Wanganui East. Photo/File

The action group fighting to retain the rail overbridge in Wanganui East has costings for a replacement structure which come in at least $600,000 below Wanganui District Council estimates.

The council has suggested closing the bridge in Wakefield St, near the Wanganui East Club, because replacement would cost $1.8 million.

The wooden structure, over the Wanganui-Marton railway line, is failing and already has weight restrictions on it. Now the council is moving to bring down those weight limits even further, such is the state of the structure.

The proposal to close the bridge to all but pedestrians and cyclists fired up the local community and those who regularly use the bridge. A petition gathered more than 2000 signatures, along with about 250 written submissions arguing to keep the bridge, and these have been presented to the council.

Former councillor Randhir Dahya, who is on the action group, said that from the time council flagged concerns with the bridge the group decided it needed to be replaced rather than closed.

"We are also very conscious of the costs involved and that savings should be made, if at all possible, on the $1.8 million the council estimated," Mr Dahya said.

The group then decided to get another costing and contacted consulting engineering firm Holmes Consulting in Wellington.

Mr Dahya said Holmes Consulting, which was experienced in designing and building bridges, came up with a concept priced at $1,218,600.

Phil Gaby, a project director for the company, said his estimate included demolishing the existing bridge, geotechnical tests, creating the approaches at either side of the bridge, consents, and building supervision of the new bridge.

The design would be a two-span, two-lane bridge 11.2 metres wide. That includes a 2m-wide footpath.

Mr Gaby said skewing the abutments on either end would make the bridge shorter and therefore cheaper.

In his report, he said he may have been "a bit heavy handed" with his estimate and suggested the group get opinions from local firms Emmetts and Bullocks, both experienced in bridge building, to see if his design "will work okay".

The bridge already has weight restrictions on it, but the council has announced it will be reducing those even more from its current maximum axle weight, from 7000kg to 2500kg, and introducing a gross weight of 3500kg.