In some types of buildings, and particularly ancient buildings, damage can be caused by the dynamic displacements imposed by machinery or traffic. Criteria may be found in several Codes, for example, DIN4150 and SN 640312. A peak velocity of between 2 and 10 mm/s may generally be regarded as a limit beyond which damage may occur. There are distinctions in the Codes between ancient and modern structures. For vibrations caused by traffic, over long periods of time, there is little factual data and there is a need for research to investigate damage thresholds and to determine whether the mechanism is of the fatigue type.