120m Antenna Tower Inspection using 3D Laser Scanning

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3D Laser Scanning Inspection of 120 m Antenna Tower – Safe, Accurate Solution for Inaccessible Structures

3DScan.vn carried out a 3D laser scanning inspection of a 120 m antenna tower using a Z+F Imager 5016 to support deformation, tilt, deflection and structural axis deviation checks. For a structure that is very tall and cannot be accessed directly, 3D Laser Scanning allows data capture safely from the ground with an accuracy of < 5 mm, combined with a Leica TCR802 total station to establish a network of GCP control points, ensuring absolute coordinate accuracy across the entire model.

1. Objectives and scope

This project was implemented to assess the technical condition and geometric deformation of a 120 m antenna tower installed in a narrow mountainous area where access is limited and climbing is hazardous. Using long-range 3D laser scanning, 3DScan.vn captured data of the entire tower body, guy wires, foundations and connection details without direct contact, ensuring absolute safety for personnel and high accuracy in inspection results.

Location: Mountainous area, narrow site, 120 m steel antenna tower.
Purpose: Capture as-built condition, check tower tilt, deformation, deflection and structural connections.
Equipment used: Z+F Imager 5016 (long-range 3D laser scanner), Leica TCR802 (total station for GCP network).
Overall accuracy: < 5 mm.
Deliverables: 3D model, tilt/deflection maps, technical inspection report and point cloud data.

2. Technical implementation workflow

3DScan.vn applied a specialised measure – scan – adjust – analyse workflow for tall structures and inaccessible steel towers, combining a total-station-based GCP network to control absolute accuracy of the scan data.

a) Establishing GCP network and control grid

Established 12 GCPs around the tower base, measured with a Leica TCR802 total station and adjusted to achieve coordinate errors < 3 mm.
GCPs were equipped with reflective targets to serve as references for laser scan registration.
The coordinate system was tied to VN-2000 to ensure consistency between periodic inspections.

b) 3D Laser Scanning with Z+F Imager 5016

Performed over 350 scan stations to cover the entire tower body and surrounding area, scanning at a radius of 150–200 m.
The Z+F Imager 5016 records up to 1 million points per second with point accuracy of ±2 mm at 100 m distance.
Data was registered using the Cloud-to-Target method to ensure overall model accuracy better than < 5 mm.

c) Processing and structural deformation analysis

Extracted the tower centreline and overall tilt model.
Calculated tilt, deflection and torsional deformation based on eccentricity vectors along the tower height.
Built a 3D analysis model and deformation diagrams by height level to support the technical inspection report.
Evaluated deviations against steel structure standards TCVN 2737:1995 and Eurocode EN 1993-3-1.

3. Results and applications

The laser scan results enabled reconstruction of a high-precision 3D model of the antenna tower, supporting the inspection body and asset owner in evaluating structural safety, detecting early deformation and planning maintenance actions.

Technical 3D model: representing the entire tower body, guy wires, foundations and surrounding area.
Tilt and deflection maps: colour-coded by elevation, visualising axis deviations along the tower height.
Technical inspection report: summarising tilt, deformation, deflection, torsion and abnormal locations.
Applications: periodic structural inspection, long-term deformation monitoring, planning repairs and strengthening of tall towers.

Conclusion

The 3D laser scanning inspection of the 120 m antenna tower is a typical example of applying non-contact measurement technology to special, high-risk and inaccessible structures. With a Z+F Imager 5016 delivering accuracy better than < 5 mm and a GCP network established by Leica TCR802, 3DScan.vn provides a complete spatial dataset for deformation, tilt and stability analysis over time – a safe, accurate and cost-effective solution for high-rise structures, broadcast towers and telecommunication masts.

Need to inspect high structures, broadcast towers or special steel structures that cannot be accessed directly? 3DScan.vn offers a complete solution with 3D Laser Scanning – Z+F Imager 5016 – Leica total-station GCP network, providing high accuracy < 5 mm, maximum safety and detailed technical reporting.

Contact 3DScan.vn Hotline: 0938309808 · Email: lienhe@3dscan.vn

Frequently Asked Questions (FAQ)

Why use 3D Laser Scanning to inspect high towers instead of manual climbing and measurement?

3D Laser Scanning allows remote measurement without direct contact with the structure, reducing safety risks and labour costs. The data captured has high accuracy (< 5 mm) and fully represents tower details for 3D deformation analysis.

How can laser scan data determine tower tilt and deflection?

Processing software extracts the tower centreline and compares it with a vertical reference axis. Deviations are visualised through 3D models and tilt/deflection maps, allowing precise determination of tilt direction and deformation magnitude for each segment.

Can periodic inspections be performed and deformation compared year over year?

Yes. For each inspection campaign, scan data is captured and stored in the same GCP-based coordinate system, making it easy to compare tower deformation over the years and identify trends of tilt, torsion or deformation exceeding safety thresholds.

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