Structural Health Monitoring (HMS) bridges the gap between periodic inspections and real-time performance data. At Wood Research and Development, I deployed Resensys SenSpot wireless sensor networks on instrumented timber structures to capture live performance data under operational loading.
Why monitor?
Timber bridges deteriorate differently than steel or concrete. Decay can progress rapidly inside a member without visible surface signs between inspection cycles. Continuous monitoring catches these changes early — before they become safety issues or emergency repair events.
Sensor deployment
The Resensys SenSpot system uses wireless accelerometers and strain gauges that communicate via a mesh network to a central gateway. Installation involves:
- Surface mounting strain gauges at critical locations identified during the Level II inspection
- Installing accelerometers to capture dynamic response under traffic loading
- Setting up the gateway with cellular backhaul for remote data access
- Configuring alert thresholds for strain and vibration anomalies
The real output of an HMS system is not the data stream — it is the maintenance recommendation.
Data analysis workflow
The raw sensor data streams into a cloud dashboard where I analyze:
- Axial strain trends under ambient and live-load conditions
- Changes in neutral axis position (indicating section property changes)
- Natural frequency shifts (indicating stiffness degradation)
- Temperature and moisture correlation with structural response
Translating data into decisions
The real output of an HMS system is not the data stream — it is the maintenance recommendation. A sustained strain increase at a connection might indicate fastener distress. A frequency drop might indicate a bearing or support issue. Each data trend is evaluated against the original design assumptions and converted into a prioritized action item for the infrastructure owner.
After two years of monitoring across multiple sites, the clearest lesson is that HMS does not replace visual inspections — it makes them more targeted. You go into the field knowing where to look and what to expect.