London Underground rolling stock use a ground-level conductor rail electrification system with collector shoes for powering the train. During operation, the dynamic interaction between the collector shoes and conductor rail imparts loads on the collector shoes. Using sets of collector shoes instrumented with fibre optic sensors, the strain on the shoes is measured while the train is running along the line. This data is used to help identify areas where repairs or adjustment of the conductor rails may be required. Due to the high voltage passing through the collector shoes, fibre optic strain gauges are an ideal solution.
SCAIME proposed optical lines with OBSG-60 bonded to the shoes. MDX8000 interrogator data is sent to a CPU that also records videos of the shoes and the train position.