Australia’s road authorities must maintain ageing, increasingly trafficked networks while managing constrained budgets and rising expectations around safety, sustainability and availability.

The scale of the challenge is significant. The National Freight Data Hub forecasts that Australia’s road freight task will increase by 77 per cent between 2020 and 2050, while the Australian Local Government Association reports that councils are responsible for approximately 75 per cent of the nation’s road network.

For councils and transport authorities, repeated patching and reactive repairs are becoming increasingly difficult to sustain.

According to Mainmark’s Interim Chief Executive Officer Amy Williams, the industry needs to look beyond the immediate repair and consider when targeted intervention could deliver a better whole-of-life outcome.

“Road authorities are being asked to maintain more infrastructure, accommodate increasing traffic volumes and improve network resilience, often without a corresponding increase in available resources,” Williams says.

“The question is no longer simply how quickly a damaged section of road can be repaired. Asset owners are looking more closely at when they should intervene, how much of the existing pavement can be retained and what will deliver the best long-term value.”

Rather than waiting until a road requires extensive excavation, realignment or reconstruction, Mainmark is exploring another intervention point: when the pavement remains serviceable, but its supporting layers are just beginning to deteriorate.

Potholes, rutting, depressions and recurring patch failures are often treated as surface-level issues. However, visible deterioration can indicate a deeper problem within the pavement structure.

Moisture ingress, inadequate compaction, loss of support, variable pavement materials and repeated heavy vehicle loading can weaken the upper pavement layers. In these circumstances, resurfacing may improve the road temporarily without resolving the condition, contributing to failure.

Mainmark’s Group Technical and Innovation Manager Theo Hnat says understanding the cause of deterioration is critical to selecting the right rehabilitation method.

“Road maintenance is often driven by what can be seen at the surface, but the surface defect may only be part of the problem,” Hnat says.

“If the supporting subgrade has weakened or lost stiffness, resurfacing may not prevent the same deformation from returning. Effective rehabilitation starts with understanding what is happening below the pavement structure and whether the underlying condition can be treated.”

Historically focused on concrete pavements, slabs and large structures, Mainmark has expanded its capabilities into flexible asphalt and bitumen road networks.

The objective is not to replace conventional rehabilitation or stabilisation. It is to give asset managers another treatment option between routine surface maintenance and major reconstruction.

“By the time significant rutting, deformation or repeated patch failure is visible, the available treatment options may already be more extensive and disruptive,” Hnat says.

“We see an opportunity to identify sections that are deteriorating but still serviceable, then determine whether targeted ground improvement can address the affected zones before the road reaches a more advanced stage of failure.”

Mainmark’s road rehabilitation approach focuses on targeted improvement within the upper pavement structure.

Following investigation and engineering assessment, purpose-developed materials can be introduced through small injection points to improve identified areas within approximately the upper half-metre of the pavement.

The treatment is designed around the pavement condition, composition, deterioration mechanism, traffic loading and required engineering outcome. Instead of removing and reconstructing an entire section, work can be directed towards localised zones where support has deteriorated.

Hnat says the approach builds on more than a decade of research into resin-based ground improvement, adapted for the shallower zones often critical to flexible pavement performance.

“Approximately ten years ago, Mainmark undertook a major research and development program focused on improving ground conditions at greater depths,” he says.

“For flexible roads, the critical treatment zone can be much shallower. We have taken that technical knowledge and developed new materials and injection methods suited to the upper pavement layers.

“The methodology has also been developed alongside key road-sector clients. Field development under real pavement conditions and operational loading has been an essential part of the process.”

The process begins by establishing whether targeted treatment is appropriate. Investigation findings inform the design, while injection locations and sequencing are tailored to the project. During delivery, the pavement response is monitored against agreed criteria.

Traditional pavement stabilisation remains an important rehabilitation method. It generally involves reworking existing pavement materials, introducing a binder and recompacting the material to create an improved base.

Mainmark’s targeted injection methodology addresses a different stage of the rehabilitation cycle. Where conditions are suitable, it may enable an asset owner to improve localised deterioration while retaining more of the existing pavement and avoiding broader excavation.

“It is not a case of one method replacing another,” Hnat says. “Some roads will require conventional repair or reconstruction. Others may have localised deterioration that can be treated more selectively. Giving asset managers another option allows rehabilitation programs to become more proportionate to the condition of the road.”

Williams says this matters because road authorities are increasingly assessing projects through the lens of lifecycle performance rather than immediate repair cost alone.

“Road authorities also need to consider remaining service life, recurring maintenance, traffic disruption, material movements and the cost of future intervention,” she says.

“An option that retains more of the existing road and delays more extensive reconstruction could create value well beyond the initial works.”

Road rehabilitation can be highly disruptive. Excavation, heavy vehicle movements and extended traffic controls affect road users, communities and businesses, particularly on freight routes where prolonged closures may not be practical.

Where site and pavement conditions allow, treatment through small injection locations can reduce excavation, material handling and the work-zone footprint.

“The direct construction cost is only one part of the impact,” Williams says.

“There is also the disruption caused by lane closures, detours, restricted access and interruptions to freight or public transport. Methods that can reduce the extent or duration of those impacts deserve consideration as part of a broader asset preservation strategy.”

Retaining existing pavement materials may also support better sustainability outcomes. Reducing excavation, disposal, the use of materials and truck movements can lower the resource intensity of rehabilitation.

“Sustainability is not only about the materials selected,” Williams says. “It is also about how much of the existing asset can be retained and how long its serviceable life can be extended.”

Mainmark is seeking earlier involvement, working with road authorities, asset managers, consultants and contractors to determine where specialist ground improvement could support a wider rehabilitation program.

Williams brings nearly two decades of experience across infrastructure, rail, utilities and property sectors. Her background has given her a strong understanding of the commercial, operational and strategic pressures facing asset owners, as well as the importance of aligning technical solutions with long-term infrastructure priorities.

“The greatest value can often be created before a treatment method has been locked in,” Williams says. “Bringing the asset owner, designer, delivery contractor and specialist provider together earlier allows the team to assess the condition and develop an approach around the actual deterioration mechanism.”

Mainmark’s role is not to replace civil contractors, designers or pavement specialists. Instead, it aims to contribute specialist investigation, design input, ground improvement and implementation as part of the wider project team.

Hnat says this improves the transition from technical assessment to delivery.

“When the engineering and operational teams are closely connected, information can move more efficiently from investigation through to design and implementation,” he says.

“That continuity is valuable when working with variable ground and pavement conditions, where the treatment may need to respond to what is identified during delivery.”

Alternative rehabilitation methods require evidence that they can be designed, delivered, monitored and incorporated into established asset management processes. Mainmark’s continuing research and development program is focused on building that evidence while refining materials and injection methodologies for different pavement conditions.

“Innovation needs to be supported by testing, monitoring and transparent performance criteria,” Hnat says. “The next step is continuing to work with road authorities, consultants and research partners to build the evidence base and establish where the methodology provides the greatest value.”

Williams says wider adoption also depends on translating technical results into information that asset owners can confidently use.

“That means demonstrating not only that the treatment can improve the pavement condition, but how it fits within maintenance planning, procurement, risk frameworks and long-term capital programs,” she says. “Innovation becomes meaningful when asset owners understand where it should, and should not, be applied.”

No single material, technology or delivery model will solve Australia’s road rehabilitation challenge. Routine maintenance, stabilisation, resurfacing and reconstruction will all remain essential. The opportunity is to create a broader range of interventions and apply each one at the right point in the asset lifecycle.

“The aim is not to intervene unnecessarily,” Hnat says.

“It is to understand the pavement condition and act at the point where a targeted treatment can produce a meaningful engineering benefit, and increase the overall resilience of the network.”

Williams believes this more proactive approach could help road authorities make constrained rehabilitation budgets work harder while improving long-term network outcomes.

“We need to move beyond measuring success by how quickly a visible defect has been covered,” she says.

“The better question is whether the underlying cause has been addressed, how much of the existing asset has been preserved and when the road is likely to require intervention again.”

As freight demand increases and road networks face more challenging operating conditions, the ability to intervene earlier will become increasingly important.

Not every deteriorating road needs to progress directly from patching to reconstruction. With the right investigation, engineering assessment and treatment methodology, road authorities can rehabilitate weakened pavement layers, retain more of the existing asset and extend its serviceable life.

The next evolution in road rehabilitation is not simply repairing failure, but engineering longer pavement performance.