Deflection or bending of (super) structures can provide invaluable information about their structural integrity. A bridge, for example, is subject to dynamic loading from passing trucks and lorries, which will accumulate stresses and strains over time. As a result, the bridge will slowly deform (e.g. compaction, deflection and/or bending).

These changes in bridge shape and structure are so slow and subtle that they often go unnoticed by maintenance engineers. However, such long-term deformation is far from harmless! If undetected, collapse is only a matter of time.