Summary: Learn how Arborplan GmbH uses ground penetrating radar (GPR) to help cities protect underground utilities and urban trees. This case study highlights Arborplan’s non-destructive approach to mapping tree roots and assessing risks to water, gas, and electricity infrastructure. Their work enables utility providers to prevent damage, comply with regulations, and preserve urban greenery—delivering actionable insights for safer, greener cities.
Cities thrive when trees and infrastructure coexist, but below ground, that balance is harder to maintain. While trees provide essential ecological and social benefits, their roots can cause unseen hazards when they encounter buried utilities.
Tree roots in direct contact with underground pipes can exert tons of tensile force – far exceeding the structural limits of many pipes. Past cases of damage and accidents have led to the establishment of technical regulations and standards in Germany for detecting and mitigating root-utility conflicts.
Arborplan GmbH & Co. KG, a German company specializing in tree root scanning, has built a reputation on managing these underground conflicts. Using Sensors & Software’s LMX200 Ground Penetrating Radar (GPR) in combination with EKKO_Project software, Arborplan delivers the insights utility asset owners need to comply with regulations, prevent damage, and preserve valuable trees.
Utility Safety & Mapping Tree Roots
Many of Arborplan’s clients are public utility providers responsible for water, electricity, and district heating. They also work with gas pipeline operators and major petrochemical firms.
“The coexistence of structural roots of trees in proximity to underground utilities can lead to considerable hazards depending on the type of tree and the material of the pipes,” Arborplan explains. “Past damages and accidents in Germany led to regulations requiring the detection and elimination of these risks.”
This regulatory framework has driven strong demand for Arborplan’s expertise. Importantly, non-destructive GPR investigations offer a cost-effective alternative to excavation, which is disruptive, expensive, and often impractical in dense urban environments.
Field Methods: From Grids to Imaging
Arborplan’s surveys start with utility maps provided by clients. These maps define the measuring field, which is laid out to capture both the buried utilities and the adjacent trees.
- Survey Grids: Typically, 10 m long, with 25 cm spacing between lines, ensuring fine resolution (Figure 1).
- Ground Conditions: Data is often collected on asphalt, paving stones, or narrow grass strips. Soil electrical conductivity and resolution vary by site.
- GPR Equipment: The LMX200 is deployed for its reliability in urban environments.
Once collected, the GPR data is processed in the EKKO_Project GPR analysis software, with heavy use of the SliceView function for generating depth slices. Arborplan adjusts the velocity calibration and gain to enhance signals, paying close attention to elongated reflections that may indicate roots crossing utilities. For 3D visualization, Voxler® (from Golden Software, LLC) is employed to render pipes and roots together in volumetric space.
Roots and Utilities in Conflict
The scale of the problem is evident in Arborplan’s fieldwork. Tree roots can physically encircle and compress underground pipes. Figure 2 illustrates this starkly: a large root in direct contact with a utility pipe.
Roots don’t just apply static pressure. When trees sway in the wind, forces are transferred from the canopy down through the roots into underground utilities. Non-native tree species (for Germany) such as plane trees and cedars are particularly aggressive in encircling pipes, unlike oaks or beeches, which interact less.
Visualizing the Subsurface
Using the LMX200 and EKKO_Project, Arborplan has been able to document clear subsurface interactions between utilities and roots (Figures 3 and 4).
These visualizations provide utility managers with a precise view of where risks exist and how severe they are – something impossible with surface inspection alone.
Deliverables
Arborplan’s work goes beyond imaging. Their deliverables help utilities understand and act on risks.
- Utility-Tree Register (Leitung-Baum-Kataster): A proprietary system developed by Arborplan to provide area-wide risk evaluations. Every tree near a utility is assigned a risk rating, with recommended measures supplied to the client.
- Risk Evaluation: If roots are found near pipes, Arborplan provides targeted recommendations to remediate the issue.
“The results of the GPR measurements are used to define further actions,” Arborplan notes. “If roots are found along the pipe, targeted underground construction and botanical interventions can eliminate the danger. Only then is the utility considered safe and compliant.”
Mitigation: Protecting Both Trees and Utilities
Arborplan emphasizes that tree removal is the last resort. They employ a variety of botanical and technical measures to address conflicts:
- Selective Root Cutting: Problematic roots in direct contact with pipes are cut.
- Root-Resistant Backfill: Utility zones are refilled with special materials that prevent regrowth.
- Tree Crown Adjustments: To balance biomass after root cutting, crown pruning may be applied.
These approaches allow utilities to protect critical infrastructure while also maintaining urban greenery.
Academic Collaboration and Research Roots
Arborplan’s expertise is built on decades of study. The founder began examining tree-utility conflicts over 30 years ago, and around 10 years ago the company began applying GPR to the problem.
Working with research teams from the University of Aachen and the University of Bonn, Arborplan helped pioneer early detection efforts and documented the results. For the last two years, they have been working extensively with the LMX200 system.
Why It Matters
Root-utility conflicts don’t just cause damage: they can create safety hazards for entire communities. With regulations now mandating proactive detection and prevention, Arborplan’s services have become valuable to German utilities.
By using LMX200 GPR and EKKO_Project, Arborplan provides utilities with actionable, non-destructive insights. Their work enables safer infrastructure, regulatory compliance, and the preservation of urban trees – a win for both utilities and communities.
“The inquiry for root and utility detection with non-destructive methods is becoming more popular compared to digging because of its cost efficiency,” says Arborplan. “Our developed tree register and risk evaluations provide utility companies with the knowledge they need to act.”
Acknowledgment: Sensors & Software thanks Arborplan GmbH & Co. KG for sharing their data, images, and insights, and for their work in protecting both underground utilities and urban greenery. All photos in this article are courtesy of Arborplan GmbH & Co. KG.
Voxler is either a registered trademark or trademark of Golden Software, LLC in the United States and/or other countries.
