Engineers from the ANU and the University of Canberra have come up with an ingenious way of saving the Sydney Harbour Bridge from corrosion.
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They blast the internal rust off with a laser so powerful that it fires a power-station's worth of energy at encrusted metal and stone in one-thousandth of a billionth of a second.
The conventional way of keeping the global icon spruce is to sand-blast it - but sand-blasters can't get into the interior of the structure, with its tiny crevices and tunnels. There are about seven kilometers of internal tunnels so small that humans were unable to get in.
The result is that the 92-year-old symbol of Sydney and even Australia has been slowly rotting from the inside.
But the Canberra teams plus scientists from the University of Sydney, the Australian Nuclear Science and Technology Organisation and Transport New South Wales have found a way of inserting robots armed with the ultra-new type of lasers into the innermost parts of the metal arch.
The alternative was to allow the structure to decay as the metal degraded.
Two professors from the ANU Research School of Physics - Andrei Rode and Stephen Madden - are part of a group tasked with developing the new method using powerful, ultrafast lasers.
"We're the caretakers who get to carry it forward for the next generations to marvel at," Professor Madden said.
"When you go up there, you stop looking at the view, and you really start to appreciate the engineering in the bridge and the historical connection to the engineers of the past."
"A mammoth effort is required to look after the bridge, a large part of which is cleaning the paint and stone and replacing ageing and damaged paint," Professor Rode said.
"The arch interior has not been maintained since the bridge was built over 90 years ago and is in major need of restoration."
The team developed a laser-based approach using cutting-edge techniques to deal with large swathes of degraded paint, corroded metal and dirt-encrusted stone.
The researchers developed the new process that uses powerful lasers to rapidly remove thick paint layers with no detectable damage to the metal and stone surfaces. The great innovation was to make the pulses very powerful but very short so little heat was generated.
Very short and very powerful in the extreme: the bursts of energy were equivalent to the output of an entire power station but applied in less than one-thousandth of a billionth of a second.
This is so fast that the energy blasts away the surface layers but leaves the underlying metal structure intact and cold.
Professor Madden said that additional benefits beyond preserving the bridge emerged during their project.
"Through this new process, we reduced energy consumption whilst being economically and time competitive with established industrial-scale cleaning technologies such as sandblasting," he said.
The technique could also be useful in the aerospace, automotive and marine industries.
There are an estimated 270,000 steel bridges across the United States, Europe and Japan, all needing continued maintenance, so the market for the new technology may be very large indeed.
"The new technique has applications that go far beyond industrial processes," Professor Rode said.
Steve Evans
Steve Evans is a reporter on The Canberra Times. He's been a BBC correspondent in New York, London, Berlin and Seoul and the sole reporter/photographer/paper deliverer on The Glen Innes Examiner in country New South Wales. "All the jobs have been fascinating - and so it continues."
Steve Evans is a reporter on The Canberra Times. He's been a BBC correspondent in New York, London, Berlin and Seoul and the sole reporter/photographer/paper deliverer on The Glen Innes Examiner in country New South Wales. "All the jobs have been fascinating - and so it continues."
