Future-proofing against floods

National Precast Member Waeger Precast has designed and built a new precast bridge to withstand floods at popular weekend getaway in NSW.Every weekend hundreds of tourists head to the Hunter Valley in New South Wales. Located 29 kilometres southwest of Cessnock, the small village of Wollombi is a popular destination, known for its 19th century sandstone buildings and old timber cottages. Meandering through the area is the picturesque Wollombi Brook.

Spanning the Wollombi Brook, 2.5 kilometres north of Wollombi, is Williams Bridge, a 32-metre-long single lane bridge that was constructed in 1978 to replace an older timber bridge, which had been flood damaged.

Its deterioration led to imposition of a five-tonne road limit and a 40-kilometre-per-hour speed restriction. The Cessnock City Council was facing a bill for extensive and ongoing maintenance, or a new bridge. It opted to replace the bridge with a new reinforced concrete structure.

Time of the essence

Hunter Valley-based Waeger Constructions and its precast division Waeger Precast was contracted to demolish the old bridge and design and erect a replacement.

Waeger manufactured all components for the new 30-metre-long and 4.5-metre-wide single lane bridge. That included precast abutments, head stocks and Waeger deck bridging modules.

Owner Michael Waeger says although the project was straightforward in terms of manufacture, it was not without its challenges.

“The biggest challenge was a four-week road closure, so we had a small window to get everything done. We had to make sure everything was set up and ready to go,” says Mr. Waeger.

Challenging access 

The Williams Bridge location on Paynes Crossing Road was a relatively difficult construction site in terms of access. “There was a wide and deep water hole on the downstream side of the bridge, so we had to build a temporary work platform on the upstream side. It was a matter of coming up with a solution to get this bridge up quickly,” according to Mr. Waeger. The limited space also required a dual crane lift to get the components in place. Mr. Waeger says the challenging access and local road conditions meant crane size had to be restricted.

Open for crossing 

The new Williams Bridge is about a metre higher than its predecessor with the aim to reduce any closure caused by flooding. Construction with precast concrete ensures the bridge is low maintenance, has an open load limit, provides strong flood resistance and has a 100 year lifespan.

Mr. Waeger says the speed and fabrication of the bridge met all expectations. “This project was a good showcase for precast in terms of the short time required to complete the whole bridge and get it reopened for public access.” The bridge reopened in April 2016.

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