Predicting Tree Root Trouble for Smarter Cities and Cleaner Sewers
It might sound surprising, but some of the most damaging infrastructure issues lurking beneath our streets aren’t caused by traffic, time or poor workmanship – they’re the work of street trees. Specifically, their roots.
In cities across the globe, sprawling tree root systems are quietly breaking into sewer lines, causing major headaches for homeowners, councils and utilities alike. Repair bills run into the millions, water supplies become contaminated, and the damage keeps coming back. For decades, the go-to strategy has involved cutting back or chemically burning the roots. But as a new Australian study makes clear, that approach is only pruning the problem.
A team of engineering researchers from the University of South Australia’s Sustainable Infrastructure and Resource Management (SIRM) group has sounded the alarm. Their findings, published in the journal Sustainability, call for a rethink in how we manage urban greenery and underground utilities.
“Tree roots are the most common cause of pipe failures in many cities around the world,” says Professor Chris Chow, a water science and engineering expert and senior author of the study.
Adelaide as a Case in Point
If you’re wondering just how widespread the issue is, look no further than Adelaide. In 2020 alone, South Australia’s water utility, SA Water, recorded over 30,000 instances of root intrusions into sewer pipes. That’s not a typo. That staggering figure accounted for nearly 60% of all sewer failures in the city. Unsurprisingly, the utility is forking out close to $5 million annually just to deal with these blockages and the resulting damage.
It’s a pattern repeated worldwide. In cities from Los Angeles to London, Auckland to Amsterdam, the battle between trees and pipes is relentless. Most cities rely on mechanical root cutting or chemical treatments, both of which are stopgap fixes. The roots grow back, often more aggressively, and the cycle begins again. Worse still, the chemicals used to kill the roots often leach into the soil, harming other plant life and potentially seeping into groundwater supplies.
Predictive Maintenance: The Smart Alternative
So what’s the alternative? According to the UniSA team, the answer lies in moving from reactive to proactive.
Rather than waiting for roots to cause chaos, the researchers advocate for predictive maintenance strategies. The idea is simple but powerful: use data to forecast where tree root problems are most likely to crop up, then intervene early.
“It’s essentially an early warning system,” explains Oliver Yang, the paper’s lead author and a Master of Research graduate at UniSA. “We can map out high-risk zones and guide smarter planting choices, better pipe materials and targeted maintenance.”
Their proposed models consider a whole host of variables: pipe age, diameter, material, local soil type, climate conditions and nearby vegetation species. This multifactorial approach is a big step up from current modelling tools, which largely focus on mechanical pipe failure without considering biological influences.
Getting the Data Right
Of course, data is only as useful as its accuracy and local relevance. That’s why the research team is urging water utilities to develop region-specific models. A predictive tool calibrated for dry, sandy Adelaide won’t necessarily apply in humid, clay-rich Singapore.
The study emphasises the importance of creating flexible frameworks that incorporate both vegetation characteristics and infrastructure profiles. For instance, different tree species pose varying levels of risk. Eucalyptus, poplars, jacarandas, desert ash and willows have highly invasive roots that actively seek out moisture, especially in drought-prone or compacted soils.
Meanwhile, other species such as hackberry, brush box, willow myrtle, lacquer trees and kurrajong tend to play nicer with underground utilities. Knowing the difference could be the first step toward city planning that doesn’t compromise infrastructure.
Greener Streets, Smarter Planning
Balancing the environmental benefits of street trees with the hard realities of infrastructure protection is a challenge, no doubt. Trees provide shade, clean the air, reduce stormwater runoff and make our neighbourhoods more pleasant places to live. But the cost of mismanaging their placement can be staggering.
Instead of removing trees or issuing blanket bans on certain species, the UniSA researchers suggest smarter city planning. Predictive analytics can help determine the safest distance between pipes and planting areas. They can also inform which pipe materials should be used where – for example, switching to root-resistant PVC or using jointless pipeline technology in high-risk zones.
In short, it’s about planting the right tree in the right place. And doing it with a solid understanding of what’s going on underground.
Technology and Innovation Driving Urban Resilience
The concept of using data to prevent infrastructure failure isn’t new, but applying it to bio-intrusions is still gaining traction. However, momentum is building. Advances in Geographic Information Systems (GIS), machine learning and environmental modelling are making it easier than ever to process large volumes of urban infrastructure data.
Initiatives like the City of Melbourne’s Urban Forest Visual and Toronto’s Tree Protection Zones already leverage mapping tools to manage urban tree planting more sustainably. Now, coupling those efforts with underground pipe modelling could mark the next big leap in city infrastructure resilience.
As Yang puts it: “Globally, cities are spending millions each year fixing the same problems over and over. With the right data and modelling, we can address this, saving money, protecting infrastructure and still enjoying the benefits of urban greenery.”
What’s Next? Building Tools for the Future
The publication of this study is just the start. The researchers are now calling for further investment in developing regionally calibrated predictive tools and for councils, utilities and planners to get on board. There’s also a need for greater public awareness, particularly among homeowners and developers, about which trees to plant and where.
Future iterations of these models could incorporate real-time monitoring using IoT sensors embedded in sewer systems or even drone-based root mapping. Collaboration with arborists, soil scientists and civil engineers will be crucial in building comprehensive predictive frameworks.
With more than half of the world’s population now living in urban areas – a figure set to rise in coming decades – the need to make cities smarter, greener and more resilient has never been more pressing.
Looking Ahead with Roots in the Right Place
Urban trees don’t have to be the enemy of urban infrastructure. Managed intelligently, they can be part of the solution. With a shift in strategy – from reactive maintenance to predictive planning – cities can break the cycle of costly, recurring sewer failures.
The takeaway? Don’t wait for the roots to take hold. By investing in predictive tools, local knowledge, and interdisciplinary collaboration, urban centres worldwide can enjoy the shade of their street trees without fearing what’s happening beneath the pavement.
