Instruments are used to characterize initial site conditions. Common parameters of interest in a site investigation are pore-water pressure, permeability of the soil, and slope stability.
Instruments are used to verify design assumptions and to check that performance is as predicted. Instrument data from the initial phase of a project may reveal the need (or the opportunity) to modify the design in later phases.
Instruments are used to monitor the effects of construction. Instrument data can help the engineer determine how fast construction can proceed without the risk of failure.
Instrumentation can be used both to enforce the quality of workmanship on a project and to document that work was done to specifications.
Instruments can provide early warning of impending failures, allowing time for safe evacuation of the area and time to implement remedial action. Safety monitoring requires quick retrieval, processing, and presentation of data, so that decisions can be made promptly.
Instrument data can provide evidence for a legal defense of designers and contractors should owners of adjacent properties claim that construction has caused damage.
Instruments are used to monitor the in-service performance of a structure. For example, monitoring parameters such as leakage, pore-water pressure, and deformation can provide an indication of the performance of a dam. Monitoring loads on tiebacks or rock bolts and movements within a slope can provide an indication of the performance of a drainage system installed in a stabilized slope.