On a bridge or viaduct, what is at stake is the safety of those crossing it and the responsibility of those who manage it. Italy's bridge guidelines have made knowledge of a structure's condition a documentary obligation, and continuous monitoring meets that obligation while delivering a management advantage: it catches degradation early, directs maintenance where it is needed and reduces closures and emergency works. To visual inspection, BBOX 2.0 adds the real behaviour of the structure, measured continuously and interpreted in a signed report.
What changes over time on a bridge
A bridge works every day under traffic and thermal cycles, and over time it is affected by riverbed scour at the base of piers and abutments, ageing of the bearings and deterioration of materials. These are slow processes that show up in the structure's behaviour before they become visible. A change in natural frequencies signals a change in stiffness. A growing inclination on a pier or abutment signals movement of the foundation.
A visual inspection captures the condition of the structure on a given day. Continuous measurements fill the time between one inspection and the next and make every reading comparable with the structure's baseline. Across a portfolio of bridges, inspection and maintenance priorities are set on data.
Where the guidelines place monitoring
Italy's bridge guidelines (Ministerial Decree 578/2020, updated by Decree 204/2022) link the required actions to the structure's Class of Attention. For the High and Medium-High classes they provide for periodic or continuous monitoring systems. For the Medium class, installation is the manager's choice and leads to reclassification as Medium-High. Monitoring supports Level 3 and Level 4 assessments and accompanies in-depth verifications.
Continuous surveillance and event response on the same installation
One hardware setup covers two needs: knowing the structure over time and knowing how it responded to an event.
The structure followed over time
Continuous measurements that make the evolution of behaviour readable, with the effect of temperature compensated for.
Natural frequencies, mode shapes of the structure and inclinations of piers and abutments, read continuously and compared with the baseline, with temperature compensation to separate real degradation from seasonal fluctuation.
Objective data that complements periodic inspections and directs their priorities.
The response to the event, measured
After an earthquake, a flood or another exceptional event, the recorded response of the structure in usable form.
Accelerations and displacements recorded during the event give the managing authority the technical basis to decide promptly on any restrictions or closures to traffic.
The recorded data indicates which elements to focus inspections and investigations on, and remains as technical documentation of the event.
On a bridge the instrumentation is often heterogeneous. The BBOX 2.0 datalogger accepts any sensor with a 4-20 mA output and, through ESA units, integrates up to 36 additional sensors, including vibrating wire and IEPE. Crack meters, strain gauges and instruments already on the structure feed into the same data stream as the accelerometers.
How structural monitoring works →A signed report to base decisions on
Monitoring ends with a report interpreted and signed by a structural engineer, which takes two forms.
The periodic SHM report documents the evolution of the structure's condition with reliable data and, as the years pass, becomes its technical history: an element supporting the diligence of those who manage it.
The post-event report sets out the measured response of the structure and gives the managing authority the technical basis for decisions on traffic.
Two bridges over the Secchia
Representative installations include the Rubiera bridge over the Secchia river, a high-traffic route subject to natural erosion. Here 10 BBOX 2.0 sensors have been acquiring data in continuous SHM for over a year, with 4 recordings a day.
On the bridge over the Secchia river on the SP23 Valle Rossenna road, at Casa Poggioli between Prignano sulla Secchia (MO) and Baiso (RE), 6 BBOX 2.0 sensors measure mode shapes and inclinations over time.
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Request a consultationContinue reading
- How continuous structural monitoring works: SHM and post-event monitoring
- BBOX 2.0: sensors, datalogger and the consultation platform
- BBOX 2.0 installations on buildings, bridges and heritage sites
- Frequently asked questions on structural monitoring
- MOSI Srl: who we are and why we build monitoring systems
- Insights on regulation and the condition of the built environment