Contractors build float to move Whanganui bridge over two days

A new bridge that will cross the Whanganui River near Upokongaro is likely to be floated across. Photo / Bevan Conley

So many people want to see Whanganui's newest bridge installed that the Whanganui District Council has to work on a detailed crowd plan, says project manager Rick Grobecker.

The 130m-long pedestrian and cycle bridge is part of the Mountains to Sea/Nga Ara Tuhono cycleway, moving cyclists to the Whanganui River's west bank for the final few kilometres to journey's end at North Mole.

The bridge is built, but cannot be moved into place between Papaiti Rd and State Highway 4 south of Upokongaro until its abutments are ready and arrangements have been made.

There will be good viewing of the move from Cafe 444 on the Upokongaro side. But people watching from the Papaiti side will be in the "work zone", and arrangements for that have yet to be made, Grobecker said.

"Contractors want as few people there as possible."

No date has been set, but the move could be as late as mid-March and happen across two days. Friends and friends of friends, cyclists and engineers keep asking Grobecker about the timing.

"They're saying 'When are you going to do it, because we want to be there'."

Papaiti Rd will have to be closed - because a bridge will be across it. Traffic on SH4 will be restricted to prevent "rubbernecking". There will be at least two weeks' notice for the road closures.

The most likely way to move the bridge will be to put one end on a bogie - a wheeled trolley with floats - and tow it down to the river at low tide. It will then be towed across the river at high tide.

There will be cranes at each side to lift the ends into place on their abutments.

The Papaiti abutment still needs some work. The Upokongaro one is finished, but will have to be concreted into place when the bridge sits on it.

Southbound cyclists will cross the Upokongaro Stream bridge downriver from Upokongaro and then turn hard left and take a path underneath it to get to the new bridge.

"We don't want cyclists or pedestrians to have to cross the state highway," Grobecker said.

Part of the $2.3 million project is a 3km cycle track between the bridge and Flemington Rd. The alignment for that is complete, the shellrock base course is down and sealing is to come.

The bridge is being built by Emmetts Civil Construction, and the track by B Bullock.

The project is jointly funded by the Whanganui District Council, the NZ Transport Agency and the Ministry for Business, Innovation and Employment.