Wanganui Regional Office Media Release

30 June 2004

Bailey bridge installed on SH4 in Paraparas

Transit New Zealand will tomorrow install a Bailey bridge on State Highway 4 north of Aberfeldy in the Paraparas.

SH4 will be closed between 9.30 am and 2.00 pm while the bridge is installed near Hawkin Road, approximately 30 kilometres north of Wanganui.

Transit regional manager Errol Christiansen said the bridge would be used at the site of a large slip that occurred during storms in February.

“Transit’s contractors have made a number of attempts to stabilise the site over the last four months, but the persistent wet weather has continually hampered efforts to reinstate the road. It has become clear that the best way to manage the site is to install a Bailey bridge and leave further reinstatement work until dryer weather during summer,” he said.

The 39 metre-long, 62 tonne Bailey bridge will be constructed off-site at a roadside area nearby and trucked and craned into location to minimise the time the road is closed.

“Had the bridge been constructed where required, the assembly would have required a road closure of at least three days. By constructing the bridge off-site and transporting it in, a road closure of only four to five hours is required,” MrChristiansen said.

Mr Chrsitiansen said as well as being the most cost-effective way of managing the site, installing the Bailey bridge would ensure the road remained open to all road users. The cost to install and remove the Bailey bridge is around $40,000.

“This is a small cost when compared to the cost to the community of having the road closed as it was in February.

“The site is particularly difficult to manage. There is a stream about 30 metres below road level and the amount of water flowing in it varies considerably at this time of year.”

Mr Chrsitiansen estimated the full cost of repairing the site, which would involve stabilising the toe of the slope with large rocks and then filling above with compacted fill material, would be $270,000.

The bridge is to be transported from the assembly site to its final location using a special transport trailer and truck unit from Auckland. This unit has a 24-axle trailer with all the wheels being able to be steered. The axles are at 2.0m centres and the whole trailer can be hydraulically raised and lowered. The trailer has a load capacity of 250 tonne.

When the bridge is transported to where it is to be used, it will be lifted off the special trailer and placed in position using cranes owned by the local companies Ian Roebuck Crane Hire and Emmett Brothers Ltd.

TNZ’s local state highway maintenance contractor, Works Infrastructure, is constructing site works and bridge approaches for this bridge.

Bailey bridges

Originally developed by the British Army and commonly used by various other armed services around the world, Bailey bridging is a modular system that utilises prefabricated standardised components. Bailey bridges can be erected in a number of different configurations using only light equipment and predominantly non-specialised labour. The system is often used in emergency situations to rapidly restore access where roads or bridges have been washed out by floods.

Transit New Zealand has a large stock of the modular sections held in readiness, to be used in situations such as this current site. Following the February storm earlier this year, a number of Bailey bridges were erected to restore road links.

Bailey bridge components are owned by Transit New Zealand but managed and erected by contractors, Eastbridge Ltd. from Hawkes Bay.

ENDS

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