Detecting railway under-track voids using multi-train in-service vehicle accelerometer

The Siemens Tracksure track monitoring system is being developed in collaboration with Rail Safety and Standards Board (RSSB) and the Institute of Railway Research at the University of Huddersfield. It makes use of the existing on-board GSM-R cab radio present in every train in the UK, through the fitment of a sensor card, which detects track condition over three axes of train vibrations. By using advanced on-train signal processing, Tracksure only requires a small amount of data to be transferred to the Ground System. For voided switches and crossings (S&C), the GPS location allows the S&C asset number to be identified and reported. This ensures maintenance staff are accurately directed to the location of voids, minimising time spent inspecting and maintaining track and improving safety. The Ground System monitors the voids detected by multiple trains, to increase the reported accuracy (within 5m) of voids and to reduce false alarms. Automated void reporting, including whether the voids are located at S&C or other track types (such as plain-line track or bridges), allows maintenance to be directed and planned. The Ground System provides advanced warning of track defects, allowing more effective and prioritised preventative maintenance. The real benefit of Nexus Tracksure is that, by way of a simple activation, it can be present on every train within the UK. Tracksure would therefore be monitoring the track on a large number of train journeys, providing a network-wide track monitoring system. Recent on-train trials have shown that the small low-cost sensor is able to detect voided sleepers underneath both S&C and bridges. The repeatability between trains and for different journeys was found to be excellent. The Network Rail upgrades to the Siemens cab radio, planned for the next 2-3 years include a GSM-R/GPS antenna, and the addition of a GPS module to the cab radio, providing a GPS connection in every train. As part of these upgrades Siemens will introduce a Tracksure sensor card into the cab radio, minimising installation costs, making it hardware ready for Nexus Tracksure, the Siemens implementation of RCM (Remote Condition Monitoring). The only action needed for activation will be the upload of the software application to the cab radio. Tracksure allows the network operator to make significant reductions in maintenance and delay costs, line closures, journey re-planning and speed restrictions, by having a reliable monitoring system that is non-intrusive yet gives analysis for the entire rail network, improving train safety, network reliability and passenger comfort.