Limited possession windows
Short service breaks favour sampled sections, leaving weeks between observations.
Smart Tunnel Scanning Solution
Scan the full line during daily train operations
STS combines onboard laser scans with TIDS positioning to detect clearance intrusions, identify tunnel-wall defects and build a 3D record during service. It produces records in 5 m segments without a dedicated inspection vehicle.
From periodic surveys to routine scanning
Subtle early defects
Small changes in intrusions, seepage, cracks and spalling can escape visual inspection.
Difficult follow-up
Without mileage, coordinates and raw point clouds, verification often requires another visit.
| Dimension | Manual inspection | STS |
|---|---|---|
| Frequency | Weekly to monthly section sampling | Per-run scanning during daily operation |
| Defect location | Manually estimated location | Mileage and 3D coordinates; centimetre-scale mileage positioning requires project validation |
| Retained evidence | Separate photos and notes | Continuous point-cloud records for review and comparison |
| Track possession | Requires a service break | Runs with service trains without a separate survey possession |
System components and scanning
Onboard equipment
Onboard equipment comprises the STS host, laser scanner, time-alignment unit and DPP status panel for processing and storage, profile capture, aligned records and health indication.
Onboard TIDS
Supplies position, speed and direction over Ethernet with link-health monitoring. Positioning and timing for trains without TIDS require separate confirmation.
STS cloud platform
Overview, defect statistics, trends, archives and downloads.
Scanning principle
Align 200 Hz tunnel profiles with TIDS position and speed by timestamp, split into 5 m segments and evaluate each to create a record with mileage and coordinates.
How coverage accumulates
Each scan captures one profile; train movement covers the tunnel length. Repeated runs increase coverage density, and lower speeds produce denser point clouds. This allows each run to scan the full line.
Vehicle integration
Choose roof or coupler mounting for the vehicle and clearance conditions. GB 50517 and EN 50155 inform the design; project documentation determines conformity.
Clearance intrusion detection
Detection method
Scan the track area in 5 m segments, compare the point cloud with clearance models and trigger an alert on intrusion.
Three clearance models checked in parallel
Structural clearance, kinematic envelope and a user-defined clearance envelope.
Straight and curved track adaptation
Identify track curvature and adjust scan parameters to maintain comparable judgement accuracy on straight and curved sections.
Output
Intrusion depth and 3D coordinates; normal regions are black and intrusions highlighted red.
Alarm fields
Timestamp, triggered envelope type, line section, precise mileage, direction, track Link ID, intrusion coordinates and raw PCD file.
The system records clearance decisions and evidence. The operator determines object nature and action under site procedures.
Tunnel-wall defect detection
| Defect | Detection scope | Output |
|---|---|---|
| Seepage | Seepage, wet patches and water streaks | Mileage and 3D coordinates for tracking changes in extent |
| Cracks | Continuous and network cracking | Direction, length, width and density |
| Concrete spalling | Broad spalling, fallen pieces and rockfall risk locations | Defect report and falling-piece risk indication |
Enable the three tasks independently by maintenance priorities. Store each defect type in a separate directory; alerts retain time, type, station section, mileage, geographic coordinates and PCD evidence.
Width detection responds strongly to surface-wet cracks but has limited performance on dry cracks. Alerts locate cracks; specialist assessment is needed for depth and structural significance.
3D tunnel records
Processing workflow
Export raw points as standard PCD, align them with CSV mileage logs and build a full-line 3D record using straightened modelling. Each PCD holds accumulated points for one TIDS interval to preserve sequence.
Four uses
| Use | Description |
|---|---|
| Deformation monitoring | Compare the same section across periods to observe deformation trends |
| Lifecycle records | Traceable records from handover through maintenance |
| Defect visualisation | Show spatial distribution and development of cracking and leakage |
| Decision support | Inform maintenance plans, spares planning and safety assessment |
Deformation comparison accuracy measures relative change at one location across periods. Minimum detectable target size, listed under performance, is a separate measure and must not be substituted for it.
Detection performance by speed
Minimum detectable intrusion, seepage and damage size
| Speed | Straight track | Curve (R=300 m) |
|---|---|---|
| 20 km/h | ≥83×47 mm | ≥84×47 mm |
| 40 km/h | ≥167×47 mm | ≥168×47 mm |
| 60 km/h | ≥250×47 mm | ≥252×47 mm |
| 80 km/h | ≥333×47 mm | ≥336×47 mm |
Minimum continuous-crack region
| Speed | Minimum continuous-crack region |
|---|---|
| 20 km/h | ≥165×20 mm |
| 40 km/h | ≥335×20 mm |
| 60 km/h | ≥500×20 mm |
| 80 km/h | ≥667×20 mm |
Targets must span ≥3 radial frames and ≥5 points per frame. Validate reflective and absorbent surfaces onsite. These test figures depend on speed, material, mounting angle and tunnel conditions.
Cloud review and traceability
Deployment
A dedicated cloud server is isolated from other product services, supports 24-hour access and allows expansion.
Three entry points
Overview, statistics and raw-data downloads.
Four data functions
| Function | Description |
|---|---|
| Multidimensional search | Filter by type, time and location; inspect all alarm fields and download linked PCD |
| Historical retention | Retain approximately three years of intrusion, seepage, crack and spalling logs |
| Dual-window comparison | Compare defect distributions and counts across periods and sections side by side |
| Batch download | Download five raw PCD files per batch; buffer offline and resume transfers; export xlsx, csv and pcd |
Statistical views
Monthly top-five sections by defect share, bar charts comparing counts by date and section, and a 30-day trend overlaying total events with intrusion growth.
Offline continuity
Historical results and logs remain available in the cloud while the train is offline. Missing results upload automatically when it reconnects.
Last updated