Aussie science rolling potholes for good

If John Lennon reckoned 4000 potholes in Blackburn, Lancashire songworthy*, he might have devoted an entire album to the state of Australia's roads after months of rain and floods.

An estimated half of the nation's $16 billion public roads budget is spent on maintenance and repairs, according to Infrastructure Partnerships Australia.

State governments invest more than $5.5 billion and local councils a further $1.5 billion, figures that will no doubt blow out considerably following the east coast's recent big wet.

NSW maintenance crews alone filled more than 18,000 cracks, craters and cavities between February and November, many of them plugged one day and in need of refilling the next as the deluge continued.

Yet not all is lost.

Enter what a group of Australian scientists are calling "intelligent compaction" technology, which can be integrated into heavy rollers to assess in real-time the quality of road base works.

Developed at the University of Technology Sydney, the innovative machine-learning process uses data from a sensor attached to the machines to help reduce the likelihood of potholes occurring.

Hopefully, the results will mean less maintenance and safer, more resilient highways and byways.

Winter's extremes have highlighted the importance of road quality, with poor construction responsible for widespread surface damage and subsidence, says study leader Associate Professor Behzad Fatahi.

Not only is this a recipe for tyre blowouts and structural harm to cars and trucks, it increases the chance of serious accidents.

"We have developed an advanced computer model that incorporates machine-learning and big data from construction sites to predict the stiffness of compacted soil with a high degree of accuracy in a fraction of second, so roller operators can make adjustments," he explains.

"Like Goldilocks, the compaction needs to be 'just right' to provide the correct structural integrity and strength."

Roads are made up of three or more layers, which are rolled and compacted: the subgrade is usually soil, followed by natural materials like crushed rock and then asphalt or concrete.

The variable nature of ground and moisture conditions can make it hard to achieve the right balance.

"Over-compaction can break down the material and change its composition and under-compaction can lead to uneven settlement," Prof Fatahi says.

"A well-compacted multi-layer road base provides a stable foundation and increases the capacity of a road to bear heavy loads."

By that, he means laden trucks weighing in at up to 40 tonnes that can readily expose cracks and weak spots in asphalt.

The research team is currently looking to test its technology onsite for road, railway and dam construction projects.

* The 1967 Beatles hit A Day In The Life, written by Lennon, was partly inspired by a local newspaper story headlined "The holes in our roads".