This International Standard provides guidelines for dynamic tests and investigations on bridges and viaducts. It classifies the testing as a function of construction and usage, indicates the types of investigation and control for individual structural parts and whole structures, lists the equipment required for excitation and measurement, and classifies the techniques of investigation with reference to suitable methods for signal processing, data presentation and reporting. This International Standard provides general criteria for dynamic tests. These can supply information on the dynamic behaviour of a structure that can serve as a basis for condition monitoring or system identification. The dynamic tests detailed in this International Standard do not replace static tests. The tests may seek to define all of the dynamic characteristics of each mode of vibration examined (i.e. frequency, stiffness, mode shape and damping) and their non-linear variation with amplitude of motion. This International Standard is applicable to road, rail and pedestrian bridges and viaducts (both during construction and operation) and also to other works (or types of works), provided that their particular structure justifies its application. The application of this International Standard to special structures (stayed or suspension bridges) requires specific tests which take into account the particular characteristics of the work. NOTE Hereinafter in this International Standard, the term “bridges” means “bridges and viaducts”.