ISO 18674-3:2017 specifies the measurement of displacements across a line by means of inclinometers carried out for geotechnical monitoring. General rules of performance monitoring of the ground, of structures interacting with the ground, of geotechnical fills and of geotechnical works are presented in ISO 18674‑1.ISO 18674-3:2017 also refers to deflectometers (see Annex B) to supplement inclinometers for the determination of horizontal displacements across horizontal measuring lines.NOTE In general, there are two independent displacement components acting across measuring lines. Inclinometers allow the determination of the two components for vertical measuring lines. For horizontal lines, inclinometers are limited to the determination of the vertical component only.If applied in conjunction with ISO 18674‑2, ISO 18674-3:2017 allows the determination of displacements acting in any direction.ISO 18674-3:2017 is applicable to:- checking geotechnical designs in connection with the Observational Design procedure;- monitoring of geotechnical structures prior to, during and after construction (e.g. natural slopes, slope cuts, embankments, excavation walls, foundations, dams, refuse dumps, tunnels);- deriving geotechnical key parameters (e.g. from results of pile load tests or trial tunnelling);- identification and monitoring of active shear planes in the ground.NOTE ISO 18674-3:2017 fulfils the requirements for the performance monitoring of the ground, of structures interacting with the ground and of geotechnical works by the means of inclinometers as part of the geotechnical investigation and testing in accordance with References [1] and [2].