For Australia’s early settlements, roads provided a vital connection from town to city and beyond.
During construction, engineers implemented safety measures they thought provided the best fit at the time. In the case of many of Australia’s rural areas, these included floodways.
Floodways are typically utilised where it’s impractical to install a bridge or culvert over a river crossing. In many instances, Australia’s early settlers opted for the former due to Australia’s low-lying rural expanses.
However, the challenges for safety and the functionality of floodways in Australia today lies in the context, says ARRB Principal Research Engineer Safe Systems Peter Aumann.
The context needs to be relevant, Mr. Aumann says. He explains that currently we use a range of signs across Australia’s floodways. This won’t always work, as each floodway is different.
Even if local road crews are aware of all of the relevant floodways, it’s not practical or easy to maintain floodway safety measures, such as relevant warning signs, all to a certain standard. As they could be hundreds of kilometres from the nearest settlement.
“I think what we need to recognise is the road network in Australia, and that most of these floodways are on rural, low-level roads,” he says.
Warning signs present at floodways mostly form the basis for Australian standards, he says.
Mr. Aumann explains that Australia’s floodways are managed by road agencies or local governments and the ARRB often refers them to the Australian standards for guidance. While physical warning signs mostly form the basis for Australian standards, Mr. Aumann says it’s the depth gauges at floodways that provide crucial information for drivers when crossing a flooded section. Current depth gauges at floodways are limited in fully measuring whether or not a floodway is safe to cross.
The velocity of the water combined with the depth is where the issue lies for current floodway measuring devices.
“What’s hard to show is how fast it’s flowing,” Mr. Aumann explains.
He discovered many of these drawbacks as Quality Manager for Austroads’ Safety Provisions for Floodways Over Roads Study, released in April.
The aim of the study was to research effective ways of alerting drivers to the dangers of crossing a floodway when it is under water. The study finds not only that current standards aren’t enough but that many of the 20,000 floodways across Australia and New Zealand lack signage required by Australian standards.
The study asserts that some floodways lack water depth gauges and other relevant safety measures.
Local government bodies and road agencies contributed to the data presented in the study over the two-year period. The study finds that a lack of reliable records on floodway incidents make it impossible to determine the scope of the safety problem.
The study finds that public advice currently provided on crossing floodways is not seen as realistic, practical or appropriate and Mr. Aumann agrees that “ambitious” drivers may be part of the issue.
“Not all of them, but certainly some of them,” he says.
Drivers who travel the same roads frequently and get just a little bit wet when crossing a floodway are probably going to do it again, he says. These road users become ambitious in crossing a floodway or in judging its depth and velocity. So when a floodway is flooded, they are more likely to be put in danger.
The study asserts that the safety message issued by road agencies, media and emergency services during times of flooding – “never drive, ride, walk or play in flooded waters” is a very safe but impractical approach because people aren’t following it. Uncertainty lies in whether the pavement is still there or not, and the actual depth and velocity of the water.
It states: “While this message is most appropriate (litigation concerns) it is not seen to be a practical approach given that too often drivers have satisfactorily negotiated a flooded roadway due to the pressures to get home, to work or to medical services etc.”
Data collection for the study included workshops with stakeholders, informing them of the issues with Australia’s floodways and the changes that must take place.
However, Mr. Aumann says that it’s not just a change of our mindset on the topic of floodway safety that needs to happen.
“We need to approach it in different ways,” he says. “I think as a road manager, you do need to manage the road but it’s all relevant to the circumstances.”
Mr. Aumann says that research looked at systems being trialled in the United States. The country contains big expanses of low-lying rural areas, not so dissimilar to that of Australia.
The study finds that automated warning systems for drivers to make appropriate crossing decisions are a viable option.
“There are some automatic systems that are being trialled in the United States about water flow that can measure depth and velocity,” says Mr. Aumann. Once the water reaches a certain mark and triggers water flow data at the site, a barrier comes down to stop drivers crossing.
“One of the drawbacks with that is that it’s in its infancy,” he adds.
Another issue is cost. The study suggests that a trial of various automated warning systems could be undertaken in Australia and New Zealand to assess their effectiveness, cost and benefits. It goes on to state: “If automated warning systems can be proven to be effective, it is most unlikely that widespread installations would be possible for the many thousands of significant floodway crossings in Australasia, due primarily to costs.”
One option considered in the report, Mr. Aumann says, is a different type of marker that can inform drivers of the depth and velocity of the water, and advise when it is safe to cross.
However, Mr. Aumann says that many of the improvements to floodways and how they are managed are circumstantial, as new treatments may need to be trialled to ensure the drivers respond to the treatment correctly.
The study proposes the implementation of improved measures at floodways should consider a management strategy that assesses risk, appropriate treatments and the resources needed to bring about improvements in the long term.
The study recommends the use of yellow flashing beacons/message signs in trials to ascertain driver compliance. It also proposes the use of automated gates at very critical and high-risk locations to immediately close off a flooded roadway, taking into account depth and velocity calculations.
The report recognises that liability issues do exist with proposed new depth gauge systems included in the study and that they may require law changes
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