ABSTRACT
This chapter reviews some of the techniques which can be used to measure the deflection of sleepers in ballast, and describes the difficulties associated with each of these. The problems associated with double integrating acceleration signals by analogue methods are discussed. A new digital technique for double integration of acceleration signals is then presented. A digital processing technique to double integrate the acceleration record produced by a passing train and so to determine the dynamic deflection of sleepers under the train gives promising results. The acceleration record can be split into a number of blocks, whose positions are determined from a processed copy of the raw data. Each block is then double integrated, and the results are pieced together to give the complete deflection record. The technique depends on the accurate recording of the acceleration signal, which requires careful selection of measurement equipment and configuration.
