What is observed
Movement and deformation of the structure and of the ground that carries it, at a frequency chosen for the behaviour expected.
Measure how a bridge is actually behaving — displacement of piers, abutments, approach embankments and deck — by combining satellite InSAR, camera-based PhotoMonitoring™ and in-situ instrumentation. NHAZCA does not sell sensors. We deliver the interpreted picture that inspection teams and asset owners can act on.
Chosen by infrastructure operators, public bodies, contractors and engineering firms across Europe
A bridge monitoring system is the combination of measurement techniques, acquisition schedule, processing and interpretation used to observe how a bridge behaves over time — displacement and settlement of piers and abutments, deformation and level change of the deck, movement of bearings and joints, crack progression, and movement of the ground supporting the structure — and to turn those measurements into evidence the owner can use for inspection planning, maintenance prioritisation and safety assessment.
It does not replace inspection. An inspection describes the condition of the structure at one moment; a bridge monitoring system describes its evolution. A few millimetres of pier movement per year is invisible to the eye, and it is exactly the signal that changes an intervention priority.
Movement and deformation of the structure and of the ground that carries it, at a frequency chosen for the behaviour expected.
Radar interferometry from satellite and from the ground, measurement from repeated images, and instrumentation on the structure — combined, not ranked.
Giving the owner comparable evidence over time, to schedule inspections, target maintenance and justify structural investigation.
Most bridges in service were built decades ago, to design loads and durability criteria that are no longer current, and they now carry heavier and denser traffic. Owners run structured inspection programmes and hold large portfolios of structures — but a periodic inspection is a snapshot, and the decisions that cost the most money need a trend.
Carbonation, reinforcement corrosion and degradation of bearings and joints progress slowly and unevenly along a structure, rarely at the point where the last inspection looked.
Differential settlement, movement of the ground at the abutments and scour in the channel act on the structure from below, often with no visible sign on the deck.
Asset owners have to rank hundreds of structures with uneven records. Objective, comparable measurement is what separates a real priority from an assumption.
After a flood, a seismic event or a strengthening intervention, someone has to say whether — and by how much — the behaviour of the structure has changed.
The recurring constraint is operational: a bridge in service cannot be stopped. Any activity requiring access to the deck, the soffit or the piers means traffic interference, site set-up cost and risk to the crew — and it has to be repeated every time the instrumentation needs maintenance.
Almost every offer on this market is built around hardware: accelerometers, tilt nodes, strain gauges, load cells, data loggers. Those instruments are useful and NHAZCA specifies them when the engineering question requires them. But a sensor measures the point where it is fixed, it has to be installed on a structure that stays in service, and it produces data that somebody still has to read.
NHAZCA starts from the other end: first the decision the owner has to make, then the techniques able to measure the relevant quantities with adequate geometry, frequency and quality — usually starting from what is already observable remotely, including years of past behaviour reconstructed from the satellite radar archive before anyone visits the site.
Expected behaviour, quantities to observe, decisions to support and the operational constraints of a structure in service.
Techniques, measurement points, viewing geometry and frequency; historical reconstruction wherever archive data allows it.
Remote and in-situ measurement, with quality control and explicit checks on coverage and data coherence.
Maps, time series and technical notes that connect the measurement to the behaviour of the structure, with the limits stated.
From remote and in-situ acquisition to one interpreted picture of how the structure behaves.
In a bridge monitoring system, technique selection follows the structure, the magnitude and rate of the expected movement, and the update frequency the decision needs. In practice the techniques are combined.
Radar interferometry from orbit measures millimetre-scale displacement of piers, abutments, approach embankments and the ground around them, and reconstructs years of past behaviour from the archive before any site visit. Update frequency is tied to satellite revisit and measurement is along the line of sight, so viewing geometry and the availability of stable radar targets define what can be resolved on a given structure.
NHAZCA proprietary technology. It measures displacement and change from repeated images taken by cameras positioned away from the structure — in some cases reusing cameras already installed on site. That allows near-continuous observation with nothing fixed to the deck, at a fraction of the cost of a dedicated radar installation. The processing chain separates real movement from lighting, vegetation and image co-registration effects.
Installed on stable ground facing the structure or the ground behind it, terrestrial radar returns displacement maps and time series at high temporal resolution. It is the option of choice when movement is fast or safety-critical and access to the structure is impractical, subject to the same line-of-sight and signal-coherence limits as any radar measurement.
Inclinometers, extensometers, GNSS and dynamic sensors answer questions no remote technique can resolve: depth of movement, absolute position, dynamic response under traffic. When the problem is a portfolio of structures rather than one bridge, SGAM adds the asset-management layer, ranking where detailed investigation is justified on the basis of wide-area measurement.
The discipline that reads the deformation behaviour of a structure is bridge structural health monitoring: on that page you will find the method, on this page the focus is the bridge as an asset and the decisions its owner has to make.
IRIS is the NHAZCA platform for PhotoMonitoring™. It processes the incoming imagery, returns displacement maps and time series for the monitored structure, and makes the results available through a browser to everyone involved — designer, asset manager, maintenance team — with no file exchange.
Because access is web-based, the interpreted result reaches the decision-maker at the same time it reaches the analyst. That is usually where conventional monitoring contracts lose the most time.
An orientation table. The real combination is defined on the structure, on the behaviour expected and on the decision the monitoring has to support.
| What the owner needs to know | Technology or approach | Output | What defines the limit |
|---|---|---|---|
| How the structure has moved over past years | Satellite InSAR on the radar archive | Historical displacement time series on piers, abutments and approach embankments | Viewing geometry, availability of stable radar targets, satellite revisit interval |
| How a structure in service is behaving now, without touching the deck | PhotoMonitoring™ with fixed cameras | Near-continuous displacement maps and time series | Line of sight from the camera position, illumination, vegetation, image co-registration |
| How a fast or safety-critical movement is developing, at high frequency | Ground-based radar (TInSAR) | Continuous maps and time series over the surface in view | Stable installation position, line of sight, signal coherence |
| How the structure responds dynamically to traffic | In-situ dynamic instrumentation | Recordings and response parameters of the structure | Point measurement, access to the structure, installation and maintenance |
| Which structures in a portfolio deserve investigation first | SGAM wide-area screening | Ranked shortlist of structures requiring detailed assessment | Screening prioritises; it does not replace assessment of the individual structure |
| How everyone involved sees the results, and how quickly | IRIS platform | Web access to maps, time series and reports | Access profiles and reporting cadence agreed in the bridge monitoring system scope |
Not sure which combination fits your structure? In a short scoping call we identify the techniques suited to the expected behaviour and to the decision the bridge monitoring system has to support. Ask for a scoping call.
The value of a bridge monitoring system is not the raw measurement but the interpreted information: deliverables that are comparable over time and directly usable by the people who own and maintain the structure. Cadence, format and the boundary of the interpretation are agreed before mobilisation.
The spatial distribution of movement across the structure and its surroundings, showing which elements are active and which are stable.
How each measurement point has evolved, including reconstruction of past behaviour wherever the satellite or photographic archive allows it.
A technical reading of the results against the expected behaviour, with comparisons, the elements that need attention and the validity limits of the data.
Measured values compared with the reference thresholds set by the owner or the designer, with an exception note whenever coverage or data quality is reduced.
A bridge monitoring system measures and reports; it does not predict the failure of a structure. Reference thresholds, escalation rules and every decision about keeping a bridge in service remain with the competent owner, designer or authority. NHAZCA's responsibility is that the evidence those decisions rest on is current, quality-controlled and honest about its own limits.
Long structures in continuous service, hard to access without interfering with traffic. Remote measurement follows piers, abutments and approach embankments without setting up on the deck.
Structures on operational lines, with narrow access windows and strict safety constraints on any on-site activity. Measurement from outside the railway boundary avoids most of them.
Masonry arches, listed and heritage crossings where fixing instrumentation to the fabric is undesirable and image-based measurement from a distance is often the only acceptable option.
When the problem is hundreds of structures rather than one, it becomes asset management: wide-area screening first, prioritisation second, a targeted bridge monitoring system where it is justified.
Abutments, embankments and foundations on moving ground: the behaviour of the structure only makes sense read together with the behaviour of the ground. On the geological phenomenon itself, see landslide monitoring systems.
Retrofit and strengthening projects that need a baseline measurement before the works and a check on behaviour while they are under way.
This service is part of NHAZCA structural health monitoring services.
The published case studies below cover road, mountain-area and hydroelectric infrastructure. They are adjacent to the subject of this page and none of them has a bridge as the monitored asset. We report them for what they actually document — continuous measurement on infrastructure in service and under construction — without stretching their scope.
Public, authoritative sources on bridge inspection practice and on ground and structure deformation measurement. They provide technical context and do not endorse NHAZCA.
Nota per l'editor: non aggiungere in pagina estremi, numeri o clausole di norme o linee guida (US, UK o altri) senza verifica su fonte primaria. In questa versione il riferimento istituzionale resta volutamente generico.
It is the combination of measurement techniques, acquisition schedule, processing and interpretation used to observe how a bridge behaves over time — displacement of piers and abutments, deformation of the deck, movement of bearings and joints, crack progression and movement of the supporting ground — and to turn those measurements into evidence for inspection planning, maintenance prioritisation and safety assessment. NHAZCA delivers it as a service that integrates satellite, radar and image-based measurement with in-situ data and engineering interpretation.
For surface movement, yes. Satellite InSAR measures from orbit, ground-based radar measures from a stable position facing the structure, and PhotoMonitoring™ measures from cameras that need no access to the deck — in some cases cameras already on site. Instrumentation on the structure remains necessary when the question is dynamic response under traffic, quantities internal to the structure, or movement at depth in the ground.
Three things in particular: it requires no installation on a structure that stays in service; it covers the whole structure and its surroundings rather than a handful of instrumented points; and it can reconstruct years of past behaviour from the radar archive, which a sensor installed today can never provide. In exchange, its update frequency is tied to satellite revisit and it measures along the line of sight — so it complements instrumentation rather than replacing it where high frequency or a specific quantity is required.
It depends on the behaviour expected and on the level of concern attached to the structure. A historical analysis from the satellite archive can cover years of past behaviour in a single processing run; periodic observation updates at the cadence of satellite passes; a critical situation needs continuous observation from ground-based radar or fixed cameras. The frequency is defined with the owner, according to the rate of the phenomenon and the decision the monitoring has to support — alongside, not instead of, the inspection intervals the owner's programme already requires.
No. Monitoring provides current, quality-controlled measurements of how a structure is evolving, which supports early identification of elements that are moving and feeds the thresholds and response procedures operated by the responsible owner or authority. It does not produce a deterministic prediction of failure, and any supplier claiming otherwise is overselling the measurement.
A spin-off of Sapienza University of Rome: our monitoring comes from applied research and from geological and engineering practice.
PhotoMonitoring™ and the IRIS platform are developed in-house, not third-party tools resold with a margin.
Satellite, radar, imagery and in-situ instrumentation converge into a single technical reading, instead of four data feeds for your team to reconcile.
Measurement geometry, coverage, coherence, interruptions and temporal validity stay visible in the deliverable rather than disappearing into the summary.
Tell us about the structure, the behaviour you suspect and the decision the monitoring has to support. We will define together which quantities to measure, with which techniques and with which limits — including whether anything needs to be installed on the bridge at all.
Hero image: "A concrete Bridge" by Sridhar Rao, Wikimedia Commons, CC BY-SA 4.0 (cropped).