Continuous monitoring of points in a tram network using optical fibre grating sensors

The growth of tram and rail networks worldwide is being challenged by a demand for reducing the costs of operation and maintenance and this is driving a technology lead approach to solving the challenge. In this paper the use of an optical fibre based sensor network for continuous monitoring of the safety critical, maintenance-intensive switches on a tram network is presented. Optical fibre sensors offer significant advantages over more traditional techniques in their size, weight, EMI immunity, multiplexing capabilities and multi-parameter sensing capacities. Results are presented from a recent field trial undertaken on the Sheffield Supertram network. Prior to replacement of two sets of switches, arrays of fibre optic sensors were installed on the new switches and on a stretcher bar that were subsequently installed on the network. The strains experienced by the switchblades and stretcher bar were recorded during tram passes. The analysis and interpretation of the data provides a mechanism for in-service monitoring of the wear and degradation of such components.