General Manager, John Dunkley
28 February 2000
World First Narrows the Distance
John Dunkley's dream became reality last week as his company created an engineering first.
The Swanbourne resident is general manager of Leighton Contractors, a civil engineering and construction company, currently building the new Narrows Bridge.
Mr Dunkley and his project team have been celebrating what is thought to be an engineering world first last week with the launch of the first section of the new bridge.
"There's nothing new in pushing the bridge out in sections from one side of the river to the other," said Mr Dunkley.
"But the conventional incremental launch method was not possible for the Narrows because of the need to make it look like a twin of the existing bridge."
The 40 year-old existing Narrows Bridge is widely regarded for its arched profile. The new bridge will replicate this profile but the curved surfaces rule out the normal incremental launch methodology.
Instead Leighton has developed an innovative method some people describe as the Coat Hanger launch.
"What we are doing is launching from the inside of the girders - the structure that supports the bridge deck, rather than launching from the bottom of the girder as is done in the conventional launch technique," Mr Dunkley said.
The bridge is built in 2 halves, each comprising 12 sections that are pushed out with hydraulic jacks.
"People will see the new bridge taking shape over the next 6 months as we launch the remaining segments," he said.
The new bridge is expected to open to traffic in December this year.
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