WHEN the floods washed through Rochester three months ago, bubbles began streaming out of cracks in water-logged roads.
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So much liquid had seeped under roads that they became spongy - bitumen sagged under foot only to gently rise again as people waded away.
Stopping that has become a priority for councils and governments rebuilding not only in Rochester but throughout Australia, Michael Caltabiano says.
The Australian Road Research Board (ARRB) chief executive describes water as "kryptonite" to roads.
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"The base material of a road is just compacted gravel, so if that material is under water for 48 or 72 hours it has to completely dry out before you can put traffic on it again," Mr Caltabiano said.
"Often it gets so wet that it destroys the pavement."
It is an expensive problem. Last year's flooding events left a total Australian repair bill of $3.8 billion dollars, according to one estimate by the Australian Local Government Association.
Councils and governments may have acted quickly to build back roads in the immediate wake of the floods but the idea was to get freight moving and reopen communities, not to permanently solve design shortcomings that left them exposed to damage.
They now have the time to think about better road surfaces and more water-proof bases, Mr Caltabiano said.
"We have got to get the permanent fixes done properly, in a new way, that delivers higher levels of resilience for community infrastructure," he said.
Solutions can include bitumen, cement, lime, slags and other additives into road base gravel.
"We have the largest material science laboratory in the southern hemisphere," Mr Caltabiano said.
"Over the past five years we have been working feverishly to develop more sustainable road solutions."
New solutions do come with one drawback for cash strapped councils, though.
The road bases cost between 10 and 12 per cent more than simply compacting gravel and laying bitumen on top, as is currently standard practice.
"But for the whole of the road's life, it's cheaper," Mr Caltabiano said.
"So over the 40 years we design them for, there's less maintenance, higher value to the pavement surface, and to recycle and relay is a much better and smoother process."
Last spring's flooding was so widespread ARRB has brought in a state of the art truck to rumble down roads, using 11 lasers to reveal how road surfaces are moving.
"It's a big semi that's been operating across northern Victoria for a few weeks now," Mr Caltabiano said.
"It's the most advanced technology in the world. We are currently talking to the state government about getting one just for Victoria."