10. Automation of Spalling Condition Assessment Using Hammering Sound Judgment AI and Hammer Auto-tracking

Tunnel inspections require hammering surveys as part of special total inspections at intervals not exceeding 10 years for Shinkansen lines and 20 years for conventional lines. In addition, hammering surveys must also be conducted during regular general inspections every two years to assess spalling conditions. Hammering surveys are labor-intensive, and there is strong demand for labor-saving through digital technologies.

To address this issue, we developed (1) a technology for generating and projecting hammering necessity level heatmaps, (2) an AI-based technology for automatic hammering sound assessment, and (3) a technology for automatically recording assessment results at the corresponding hammered locations (Fig. 1).

Technology (1) extracts deformations such as cracks and water leakage from tunnel wall images using AI, and automatically generates a deformation mapping development diagram that includes hammering necessity levels (a proprietary index based on maintenance standards that indicates the need for hammering surveys).

Technology (2) converts hammering sounds into images with time on the horizontal axis and frequency on the vertical axis, and uses AI to classify the sounds as either clear or dull.

Technology (3) determines the hammering position by attaching a Bluetooth tag to the hammer and a receiver to the projection device, and then measuring the direction from which the received radio signal arrives. The hammered location is then automatically recorded together with the assessment result when hammering is performed.

Spalling conditions can be automatically assessed based on the deformation data and hammering sound judgment results obtained through Technologies (1) to (3).

The developed system can be applied to images taken by individual railway operators and can be deployed on standard freight cars being used for inspection. This enables near-complete automation of development diagram creation, selection of hammering locations in the field, and hammering sound judgment, recording, and condition assessment.