Pavement deflection: equipment for measurement in the united kingdom

significant relationships have been established between the deflection of roads measured under a standard rolling wheel load moving at creep speed and their structural performance under traffic. this research is described in lr 832 and provides the basis for the prediction of the unexpired lives of pavements and for the design of bituminous overlays. essential to the research studies and to the implementation of a design system for strengthening pavements is a convenient and reproducible method of deflection measurement. the report describes the deflection beam, which was used in the original studies, and its standardised method of operation in the united kingdom. the lacroix deflectograph, an automatic technique of measuring deflections under a rolling wheel, is suitable for carrying out deflection surveys on long lengths of road. the machine as modified for use in the united kingdom is described together with details of ancillary equipment required for carrying out deflection surveys.(a) (see also irrd abstract no 232751.)