When one talks of "safety" in large engineering construction and particularly in dams, experienced engineers as well as laymen think first of the intrinsic safety of the structure, that is, all those provisions in the design and performance of the work devised to prevent the total or partial collapse of the structures, and thus to prevent damage to future users and residents in the area adjacent to the work being constructed. Secondly, they usually consider the conditions of temporary instability of component elements, but still with a view to preventing damage that might occur to the work during its construction.