3S Tunnel Defect Inspector


It is the first tunnel inspection system based on drone and on-board Artificial Intelligence (AI) processing technology in Hong Kong. It brings digital upgrade to tunnel inspection, enabling engineers to conduct intelligent and safe inspection directly on-site. “3S” refers to “Safe”, “Smart” and “on-Site”. This system has been successfully developed and applied in the Trunk Road T2 and Cha Kwo Ling Tunnel project.

  • 3S Tunnel Defect Inspector
Commercialisation opportunities
Consulting projects; Contracting commercial and research projects
Problem addressed

Tunnel defect identification is crucial for tunnel construction. However, it is difficult to detect all defects through conventional tunnel inspection, and inspectors are required to observe with naked eye and manually record inspection results in the busy tunnel area, which is not only cumbersome, time-consuming and inefficient, but it might also lead to traffic incidents due to human fatigue.

  • Adopt state-of-art AI and robotics to achieve intelligence. By using deep neural network and transfer learning to replace the human eye detection in conventional tunnel detection, the accuracy can reach millimeter level, and the detection efficiency is also greatly improved.
  • The AI chip combined with the edge computing-based neural network makes the AI detection calculation faster and more efficient, enabling engineers to conduct intelligent inspection on-site, while responding to the inspection results quickly and immediately.
  • It innovatively combines AprilTag with QR code for positioning, which can continuously and stably detect defects on the surface of the tunnel under different locations and conditions without the need of using GPS technology.
Key impact
  • Inspectors no longer need to use mobile working platforms for inspections in heavy-traffic tunnels, which greatly reduces the need for high-altitude operations in crowded areas, thereby reducing the risk of accidents.
  • The detection accuracy is greatly improved to the millimeter level and can cover all parts of the tunnel, helping operators to identify defects efficiently and accurately.
  • Following the detection, it automatically generates the digital defect reports for digitalisation of the entire inspection process.
  • The successful upgrade and digitalisation of tunnel inspection work will help develop intelligent tunnels. This inspection systemcan also be applied to other large buildings in the long run.
  • 2022 Geneva International Exhibition of Inventions - Silver
  • Inspection of concrete structure tunnel


  • Intelligent inspection drone applied to detect concrete defects in tunnel sites (Under Application)
  • Non-GPS In-tunnel Positioning (Under Application)
Hong Kong Productivity Council (HKPC)

The Hong Kong Productivity Council (HKPC) is a multi-disciplinary organisation established by statute in 1967, to promote productivity excellence through integrated advanced technologies and innovative service offerings to support Hong Kong enterprises. HKPC is the champion and expert in facilitating Hong Kong's new industrialisation empowered by i4.0 and e4.0 - focusing on R&D, IoT, big data analytics, AI and Robotic technology development, digital manufacturing, etc., to help enterprises and industries upgrade their business performance, lower operating costs, increase productivity and enhance competitiveness. 

The Council is a trusted partner with comprehensive innovative solutions for Hong Kong industries and enterprises, enabling them to achieve resources and productivity utilisation, effectiveness and cost reduction, and enhanced competitiveness in both local and international marketplace. It offers SMEs and startups immediate and timely assistance in coping with the ever-changing business environment, accompanying them on their innovation and transformation journey.