The five reasons south-west Victorian roads are so bad

The Standard sat down with an expert on transport and pavement geotechnics - Federation University civil engineer Dr Amin Soltani - who offered five reasons the region's roads are crumbling.

When most people think of roads, they just think about the pavement and the asphalt but Dr Soltani said it was crucial to consider what the road was sitting on.

"Roads are founded on the ground, which is basically soil, and the big issue in Victoria is the poor quality soils we have," Dr Soltani said.

Clay soils are extremely expansive, which means they absorb moisture readily and expand as a result, sometimes tripling in volume. Then when the weather dries out, they bake and shrink again. Dr Soltani said this was terrible news for roads.

"The pavement structure resting on this problematic soil is constantly moving upwards and downwards and the main challenge is the amount of upward and downward motion is not the same," he said.

"This constant movement eventually leads to the pavement surface cracking and this is one of the main challenges that causes the pavement to fail."

Road engineers use cement or lime to bond with the clay soil and stabilise it but Dr Soltani said this wasn't always effective, especially in parts of Victoria where the soil contained high percentages of organic matter or minerals.

He said researchers had come up with alternative additives that could stabilise the soil but it would take a huge effort to get governments and road engineers to change their ways.

Dr Soltani said road maintenance - or "pavement management" - was the most important factor in the life of a road but it was sadly overlooked.

"This is a difficult area to address because it's expensive and not that impressive but state and federal governments should really be allocating funding to it because really it's more important than the road building itself," he said.

"You could build the best possible road but if it's not maintained and repaired it's still going to fail eventually."

Dr Soltani said there were three things that would transform road maintenance in Victoria: local crews, scheduled maintenance, and embracing AI technology.

"At the end of the day the people who maintain (roads) should be local. It just makes sense," he said.

"A local person is familiar with the type of traffic that uses the road, the application of the road and all the issues and challenges specific to that road."

But those crews wouldn't have to spend their time checking all their local roads for cracks. Dr Soltani said there was already enough data and advanced technology to do most of that work automatically.

"If we compiled all the road and pavement data we have into one database we could create a modelling framework to predict the condition of the pavement over time," he said.

"This would mean we would know when a stretch of pavement is reaching a terminal condition and we could go to the site and do rehabilitation and repair before it gets extreme and much more expensive.

"This is done to a limited extent I believe but clearly we could be doing better."

Dr Soltani said this approach would need to be local to be done right, and he thought the upfront cost was the reason the government hadn't invested in it.

"Each region needs its own dedicated program, you can't have one for the entire state, that's impossible," he said.

"So it would be expensive but the rewards over a 10-year period would completely outweigh those upfront costs."

A Transport Department spokesman said the government had implemented local repair crews.

"In fact, every aspect of our maintenance program from inspection through to delivery is carried out and overseen by people who proudly live and work in their communities in regional Victoria," the spokesperson said.

"Their local knowledge forms a key part of our road maintenance planning and delivery."

If water is a road's worst enemy, heavy vehicles come a close second. In the south-west, the rainy climate forms a diabolical partnership with the milk tankers and log trucks to tear up the region's roads.

"It's the deadliest combination ever," Dr Soltani said.

"The extreme weather, the rainfall followed by heat, will result in soil movement and cracks developing on the pavement structure.

"Most of these cracks aren't even visible."

Then come the heavy vehicles, which Dr Soltani said weighed way beyond than what the original road engineer would have planned for.

"So when these vehicles move across these microcracks they get big enough for water to penetrate and then material will start ejecting from these cracks, creating big voids beneath the pavement which means it moves even more when vehicles move across it," he said.

"At the end of all that you get a big pothole."

Dr Soltani said the only sure way of preventing those roads falling apart would be "overdesign", making the pavement or asphalt, or both, much thicker. But that would never happen because it's too expensive.

"So that's where maintenance and pavement management becomes so critical in these areas," he said.

"Whether that's done or not is another story."

The Standard revealed on January 2, 2024, the government planned to spend 40 times its annual road budget on just 15 kilometres of freeway in Melbourne, and that it would spend more on a 5.7 kilometre upgrade of the Eastern Freeway than it would allocate to regional road maintenance for the next 10 years.

"It's completely disproportionate," Dr Soltani said.

It's always been like this for regional road networks because they're not a huge source of income and they only serve specific purposes. They're actually more important than they appear but they're not valued that highly."

He said the neglect of regional roads wasn't unique to Victoria but the other vulnerabilities like the poor soil made it more obvious. He said the government had no choice but to spend huge amounts on arterial roads in Melbourne.

"When you're dealing with high volume roads like freeways in Melbourne, there's no room for error. Because the traffic volume is so high, if the road is slightly under-designed it will fail immediately and that will be catastrophic for the network," he said.

"I'd say based on the amount of money they allocate to regional and metro projects they are optimising. So they reduce quality, maybe, on regional roads, and add to the quality of non-regional roads.

"It makes sense from a purely budgetary perspective but it's not good engineering practice."

Ultimately, Dr Soltani said, it all came down to money.

"There's no point patching a bunch of potholes in a particular area because it's structurally unsound and you will quickly get the same problem again, and yet this does happen," he said.

"That's something that should be decided by the engineers on the ground but again they're probably limited not by their knowledge but by their funding, so instead of a permanent fix you get a temporary solution."

Dr Soltani said under the Austroads design guide new roads should have a design life of between 10 and 25 years but many needed significant maintenance after just one year. It's a sign something's not right.

"There's a lot that goes into road engineering with a lot of different people involved and they should all be on the same page about what they're trying to achieve but in most cases they're not," Dr Soltani said.

"That's why roads, which are really the structure that's easiest to build, have the most issues. It's probably the most important piece of infrastructure we have but we don't treat it like that. That's definitely evident to me."

But the lack of funding wouldn't be such a problem if contractors were answerable for their work when they took shortcuts.

"No one has to answer for their work. There's nothing holding anyone accountable for a road failing," Dr Soltani said.

"That's basically because the stakes are so low. If the road fails it's just a road closure. The chance of someone dying in a road failure before we can detect the problem is very low."

The Standard revealed in August 2023 the government had rewritten its road maintenance contracts to include performance-based standards that could hold contractors accountable for sub-par work.

"The fact they've incorporated new standards is good, but hopefully they actually abide by it," Dr Soltani said.

"I believe the road network should really only be done by the government, not independent private contractors with different approaches and standards."