At last - a fifth bridge linking the east and west banks of the Whanganui River is under way.

Whanganui company Emmetts Civil Construction is well on the way to constructing a 130m-long cycle and walking bridge between Papaiti and Upokongaro. It will be part of the Mountains to Sea Cycleway.

The company received an award for a very similar bridge across the Waikato River last week, at the New Zealand Bridges Summit and Awards. It was for projects under $5 million.

Their Perry Bridge south of Hamilton also won an award from ACENZ, the Association of Consulting Engineers New Zealand.

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Emmetts staff have cleared topsoil off one of the Smith family's Papaiti paddocks and are building a platform to assemble the bridge on.

The steel parts are being made by Napier engineering firm Eastbridge. They are due to arrive in two weeks, Emmetts contract manager Jeremy Emmett said, and will be bolted together.

It will be a single span network arch bridge, with the top of the arch 18m above the 2.4m-wide deck that will be suspended from it. It's the second design for the bridge, and was done by Wellington engineering company Holmes Consulting Group.

The first was to have been a cable stay structure - until test drilling found soil instability on the Papaiti side.

The abutment on the Upokongaro side will be concrete, with piles, Emmett said.

On the Papaiti side test drilling found soft soil potentially subject to liquefaction in an earthquake. That abutment will be mass stabilised earth, built up in layers, with geofabric, and compacted.

Emmett isn't sure exactly how the bridge will be moved into place once it has been built. That will probably happen in February. One section of powerlines on the Papaiti Rd side will have to be temporarily undergrounded for it.

His company won the entire $2.298m design and build contract. It is being jointly funded by Whanganui District Council, the Ministry of Innovation, Business and Employment and the New Zealand Transport Agency.

Subcontractor B Bullock is building the cycle path alongside Papaiti Rd. Photo / Bevan Conley
Subcontractor B Bullock is building the cycle path alongside Papaiti Rd. Photo / Bevan Conley

Subcontractor B Bullock has started building the cycle path alongside Papaiti Rd, from the bridge to the edge of Aramoho, a distance of about 3km. It will need a small new bridge at Flemington Rd, and an extended culvert to span another dip. It is to be sealed.

This "missing link" in the cycleway was to have run along the east side of the river, but landowners objected and parts of it would have flooded in June 2015. After the flood, and with the Perry Bridge under way, Emmett put in an alternative tender.

The bridge and new stretch of cycle path are due to be finished by April next year.

Location of the Papaiti side