Threshold-based anomaly detection for construction-induced subsidence. Catches sudden cm-scale events invisible to satellite InSAR — tested against the Purple Line tunnel leak at Wong Wian Yai.
SinkAlert's core detection pipeline uses satellite InSAR (Sentinel-1) to measure ground deformation at mm/year resolution with multi-day revisit times. This is excellent for chronic, groundwater-driven subsidence — but it is completely blind to sudden construction-induced events.
✓ 10-30 mm/year creep
✓ 12-day revisit
✓ Covers entire city
✓ Free (ESA Copernicus)
✗ 200 mm in 6 hours
✗ 30m depth (invisible)
✗ Construction defect
✗ No InSAR signal for weeks
July 9, 2026 Sump pit joint failure at 30m depth — Wong Wian Yai, Prachadhipok Road. Contractors: Italian-Thai + Nawarat Patanakarn JV (Tao Poon-Rat Burana section). 20cm road subsidence in 6 hours.
Source: Bangkok Post — verified.
Settlement rate hits 21.5 mm/day and piezometer drops 39 kPa. This is 1 hour before the major 20cm surface collapse at t=20h.
Enough time to close Prachadhipok Road and evacuate.
153mm total settlement, 152 mm/day rate, 89 kPa pressure drop. Road already closed — monitoring confirms tunnel leak is ongoing.
Pumping and grouting response underway.
Calibrated from worldwide case studies of TBM/tunnel failures. Sources: Crossrail (ICE 2015), Nicoll Highway COI (2005), Amsterdam N/S Line (van Hasselt 2009), ITA Guidelines (2021).
| Sensor | 🟢 WATCH | 🟡 WARN | 🔴 ALERT | Source |
|---|---|---|---|---|
| Settlement (mm) | 10 | 30 | 100 | Crossrail ICE 2015 |
| Settlement rate (mm/day) | 5 | 15 | 50 | Nicoll Highway COI 2005 |
| Piezometer drop (kPa) | 20 | 50 | 100 | Amsterdam N/S Line 2009 |
| Inclinometer (mm/day) | 3 | 6 | 15 | Nicoll Highway COI 2005 |
| TBM pressure dev (%) | 10 | 20 | 35 | ITA Guidelines 2021 |
| Spoil excess (%) | 5 | 10 | 20 | ITA Guidelines 2021 |
Layer 4 is a pre-ML filter — it flags anomalies using physics-based thresholds before they reach the ensemble model. This catches sudden events that would never appear in InSAR data. ALERT-level events are fed to the existing fusion engine as additional features.
detector.py)/root/sinkalert/anomaly/detector.py/root/assignments/construction-risk-enhancement-spec.md/root/assignments/purple-line-simulation-result.json