Old roads with a concrete slab pavement that has been in service for several decades are often subject to step faulting, which may result in vibrations. This distress can originate in the lack of a base layer or in the lack of stability of that layer, which is often associated with poor drainage or a weak subgrade. In old roads, this is an “ageing phenomenon” which can often be ascribed to open joints or to very old age with consequent long-term traffic loading. In younger roads, the cause of step faulting and slab rocking needs to be investigated before making repairs.
