The growing interest in continuous monitoring of critical infrastructures goes hand in hand with the need of designing efficient and affordable technology to prevent disasters due to natural hazards or structural collapses. In this regard space techniques based on Earth Observation and Global Navigation Satellite Systems (GNSS) have recently become of paramount importance for continuous monitoring, especially in those countries where hydrological hazard is relevant.

These techniques are able to accurately measure tiny horizontal and vertical displacements of critical infrastructures.

Monitoring of infrastructures like bridges and viaducts is currently carried out only during the building phase, to measure the reaction of the infrastructure to various stress factors (passages of heavy-load trucks, movements, etc.) or occasionally for structural tests during the life of the structure. However, for endogenous (ageing) or exogenous causes (heavy load, unauthorized anthropic activities, slope instability, subsidence, seismic activity, etc.), bridge or viaduct pylons can slowly tilt, move, or sink, causing a change in load distribution.

Continuous monitoring throughout the entire operating life represents a powerful tool for early warning and damage prevention.