The underground space in cities is becoming increasingly congested. The growth in the number of cables and pipelines due to the energy transition, digitalisation (such as fibre optics) and the expansion of heat networks is putting strong pressure on the available underground space. At the same time, we want to plant more trees and greenery to make cities more climate-resilient and liveable. This also means that root systems require more space. These two developments increasingly come into conflict, as roots and utilities share the same underground space. The challenge is clear: how do you protect underground infrastructure without damaging trees?
Why do tree roots cause problems for cables and pipelines?
Tree roots actively seek oxygen, water and nutrients. They are opportunistic and always follow the path of least resistance. When there is little rootable space underground or the soil structure is poor, roots can spread along existing, more open structures, such as cable or pipeline routes.
What are the consequences of the conflict between tree roots and cables/pipelines?
Damage caused by the conflict between trees and underground infrastructure can manifest in various ways, such as cable breaks, leaks, root heave and unstable trees. If cables or pipelines are installed without proper protection or consideration for trees, risks increase:
- Protective ducts or sheaths around cables may be weak or have gaps, allowing root intrusion. This can loosen or damage joints and connections.
- Soil compaction or unfavourable soil composition around cable routes reduces rootable space and forces roots towards areas where cables and pipelines lie.
- Cables and pipelines often restrict tree growth space, leading to poorly developed root systems and unstable trees.
- Intertwined roots can displace or deform pipelines, causing leaks and malfunctions.
- Root heave can push up or crack paving.
- The absence of physical barriers (such as root protection screens) gives roots free rein to grow towards infrastructure.
What are the repair costs when intervention is needed afterwards?
In practice, damage is often repaired by cutting roots or locally fixing cables and pipelines. This seems effective but does not provide a lasting solution. This approach weakens the tree or stimulates new root growth towards the same spot.
Excavation damage and direct repair costs
Damage to cables and pipelines in public spaces costs tens of millions of euros annually in the Netherlands. According to research by the Dutch Digital Infrastructure Authority (2025), nearly 50,000 excavation damages were recorded in 2024, amounting to over €57 million in direct repair costs. On top of that come indirect costs, such as traffic disruption, emergency repairs outside working hours and claims for service outages. These costs can far exceed the repair itself.
Societal damage costs
Major outages can also cause significant societal damage. SEO Economic Research (2018) describes that the societal costs of power outages are considerable. The report refers to an earlier estimate of around €72 million per hour of power outage in the Randstad during daytime (based on 2001 data), noting that these costs have likely increased since.
Who is liable for damage to cables and pipelines?
According to the Uniform Dutch Underground Excavators Regulation (UNOG, 2024), when a network operator causes damage to paving or greenery, all restoration and consequential costs are charged to that operator. This includes reinstating paving and repairing green spaces. Legally, the party that excavates or manages can be held liable for consequential damage to paving, greenery and underground infrastructure if it cannot demonstrate ‘careful’ action according to applicable guidelines. The Centre for Underground Construction (2024) states that this can be prevented through good design and prior coordination, whereas repairs often amount to emergency measures, which are structurally more expensive and riskier.
What is a sustainable way to protect cables and pipelines?
A sustainable solution focuses not on fighting roots but on guiding root growth. By directing roots in the right direction from the start, conflicts with underground infrastructure can be avoided.
Method 1: root protection and root guidance
Root protection and root guidance are proven methods to prevent or mitigate root-related issues, such as root heave and damage to underground utilities. They prevent high repair costs, safety risks and legal issues. These are underground, almost invisible methods that work simply yet effectively. According to the Tree Handbook by the Norm Institute for Trees (2022), root protection and root guidance are mainly prescribed where underground space is limited or where roots must not penetrate zones with cables, pipelines or paving – for example, when planting trees in narrow profiles or near vital infrastructure.
When do you apply root protection and root guidance to protect cables and pipelines?
As a rule of thumb, root guidance (such as Tree Root Guiding) is applied within 2 metres of the tree. Root protection (such as RootBlock or RootControl) is applied when a root barrier needs to be placed beyond 2 metres from the tree. Unlike root protection, root guidance can ensure tree stability within 2 metres of the tree.
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Root protection |
Root guidance |
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Forms a physical barrier between tree roots and underground utilities. |
Forms a physical barrier between tree roots and underground utilities. |
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Prevents root heave. |
Prevents root heave. |
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Possible to place within 2 metres from the tree. |
Not suitable within 2 metres of the tree (rule of thumb: from 2 metres onwards). |
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Ensures that roots are directed downwards and continue to grow under the panel in a horizontal direction. |
Blocks roots and allows them to grow along the wall at the same height. |
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When a root screen has to be installed within 2 metres from the tree, root guidance makes it possible to ensure the stability of the tree (by allowing the roots to continue growing under the panel). |
When a root screen needs to be placed within 2 metres from the tree, root protection cannot ensure the stability of the tree (because it blocks the roots from growing further). |
Method 2: soil cell system as cable duct
A soil cell system is an underground structure that provides trees in paved areas with an optimal growing environment, including root space, aeration, irrigation, stability, nutrients and root guidance. The structure bears heavy traffic loads, preventing soil compaction and allowing roots to develop freely within the soil cell system. The space is often filled with a special tree substrate that is water-permeable and nutrient-rich. The soil cell system consists of a modular structure placed below ground level.
How do you apply the soil cell system as a cable duct to protect cables and pipelines?
The soil cell system can be cleverly combined with infrastructure. One ‘corridor’ of the soil cell system is reserved for use as a cable and pipeline duct. Cables and pipelines are placed neatly and accessibly in this corridor. This space is then enclosed with a TreeRaft structure, with the outer side reinforced by Combigrid, a geotextile with heavy reinforcement that provides extra stability and protection against soil pressure.
When a tree is planted in a soil cell system combined with a cable duct, it is advisable to apply a root protection wall on both sides of the cable duct, on the outside of the corridor. This can be installed at various heights depending on the soil cell system’s depth. The root protection wall prevents tree roots from entering the cable duct and directs roots in the desired growth direction.
Thus, the soil cell system functions not only as a growing space for trees but also as an integrated solution for underground infrastructure – saving space and structurally preventing root conflicts with cables and pipelines.
Integrated design with trees and underground infrastructure
According to the Institute for the Built Environment (IGIB), the Netherlands risks ‘underground gridlock’. Increasingly, functions such as energy, sewerage, greenery and data compete for the same space without a well-coordinated spatial strategy. Municipalities and utility operators acknowledge the problem, but in practice, integrated coordination between design, execution and management is often lacking. A future-proof public space requires structural collaboration between the green and infrastructure sectors – from design to execution and maintenance.
Summary conclusion
The conflict between tree roots and underground utilities mainly arises from a lack of underground space and insufficient integrated design, coordination and spatial management. Trees are planted in the same underground space as energy, water and data infrastructure without timely involvement of all disciplines. This leads to root heave, cable breaks, leaks and unstable trees, with sky-high repair costs, legal issues and dangerous situations for residents and workers as a result.
There are proven techniques to resolve underground conflicts:
- Root protection and root guidance to control root growth away from cables, pipelines or paving.
- Soil cell systems with integrated cable ducts, combining tree growth space with infrastructure accessibility.
These methods are modular, maintenance-friendly and future-oriented. Only by sharing knowledge, designing integrally and taking joint responsibility can we keep underground infrastructure safe and intact while allowing trees to grow healthily and live long.