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The spectacular new bridge on New Plymouth’s coastal walkway looks from one angle like the bleached skeleton of a whale, and from another, evokes the image of a breaking wave. BY MARY SEARLE
In February the first and highly visible part of the $4.2 million extension to the walkway was dropped into place. The elegant pedestrian bridge over the Waiwhakaiho River was designed to evoke both the image of a breaking wave and a whale skeleton. The 80 metre long bridge weighs 85 tonnes and had to be moved from the yards at Fitzroy Engineering, where it was constructed, to the site – negotiating hills, trees, and damp paddocks. Heavy haulage firm Multi-Trans was responsible for getting the bridge from A to B, and company general manager Dave Butler told Contractor that because of an historic Pa site, the load had to be diverted to the nearby golf course, making its way down the edge of one of the fairways. Multi-Trans used its Scania 144G, rated at 200 tonnes towing capacity, pulling a six axle Cometto trailer and a Mercedes 3053, rated at 250 tonnes towing capacity, pushing a six axle MTE platform trailer from behind. Dave says getting the bridge to the site was a fairly straightforward heavy haulage job, but placing the bridge proved to be a little trickier.
The second complication was an environmental one. The company wasn’t allowed to put anything in the river that may pollute it, which ruled out driving any sort of machine into the water, and the job didn’t warrant using a 400 tonnes crane, Ian says. So instead, two 30 tonne crawler tractor bases were connected together and they carried the load while Multi-Trans pushed with one of its trucks and Ian Roebuck Crane Hire pulled with its crane. Ian put a 60 metre sling across the river, looping it through the snatch block on the crane. As the operator lifted the hook up he could tell how many tonnes it was pulling. The wire rope had a breaking strain of 30 tonnes, which was plenty initially, but when the first tractor base sunk into the soft sandy riverbed, the crane had to increase its load to 30 tonnes, which caused a few concerns!
New Plymouth District Council project manager Jeff Bondy says the extension opens up a section of the coast that many people have never visited. “It brings people very close to the Tasman Sea, takes them across the historic Te Rewa Rewa Reserve and also through a working farm. “It’s a great slice of the Taranaki landscape.”
Contractor Vol.34 No.3 April 2010 |
New Plymouth’s coastal walkway meanders for seven kilometres along the coastal edge of the city, from the Waiwhakaiho River Mouth in the east to Port Taranaki in the west. As well as providing a great place to stroll, run, cycle and skate, it offers great views of the dramatic west coast. The walkway is in the process of being extended by three kilometres, all the way to Bell Block.
Ian Roebuck Crane Hire was in charge of this part of the project, and there were a number of technical challenges, the first of which was that although Ian had priced this job two years ago, it was a scant seven weeks before the job that he found out where the bridge could actually be lifted (could hold its own weight) and where its centre of gravity was.
Now in place, the bridge is yet to have its deck put on and access ramps constructed. Whitaker Civil Engineering began work last month on the final three kilometres of walkway, which should be open in June.