Gnss-based Sensor Fusion for Safety-critical Applications in Rail Traffic

Due to the availability of precise satellite navigation systems, namely GPS and in the near future Galileo, which provide reference position, time and integrity information on a global and uniform basis, rail traffic is facing a revolution in terms of flexibility of operations. Autonomous satellite navigation receivers combined with a communication subsystem, so-called telematics systems, are used in a vast variety of ground transport applications today, predominantly road and maritime transportation. The railway sector was more reluctant in the past, but becomes more and more convinced about the benefits of the GNSS-based telematics technology. To conquer these demands, a mobile telematics prototype system called INTEGRAIL has been developed by KayserThrede and Bombardier Transportation during the last three years. The basic objective of the INTEGRAIL development was to demonstrate the profitable use of GNSS for advanced rail traffic management. INTEGRAIL is the first step towards providing train position, velocity and heading by means of satellite navigation to safety-critical rail applications. At this stage it allows already for the more profitable exploitation of low-density rail lines. Eventually, INTEGRAIL will provide a GNSS-based odometry interface within the already emerging ERTMS standard to serve high-speed lines as well. The working principle of INTEGRAIL combines satellite position data with traditional train sensor readings such as odometry. The INTEGRAIL platform consists of a set of state-of-the-art commercial components, which are integrated into a transportable 19” box (‘mobile unit’) and installed on-board the locomotive. A dedicated sensor fusion software performs cross-checks with a digital route data base on a regular basis and provides integrity-checked position, speed and heading data. INTEGRAIL also caters for communication with a dedicated control centre for remote monitoring and configuration control. The communication scheme is based on GSM and allows to remotely monitor the performance and to control the configuration of the mobile unit operating on the train. Extension to GSM-R is planned. ‘In-the-field‘ tests in Austria and Belgium allowed to assess the system’s performance in terms of accuracy, integrity and availability in operational day-to-day scenarios, and hence to prove the feasibility of GNSS-based sensor fusion for future use in safety-critical train location, train control or transportation of dangerous goods. The paper reports about the development, testing, performance and individual benefits of the INTEGRAIL system. Main focus is on the results of the field tests and the assessment of the system’s performance. An outlook to compatibility and interoperability with the applicable European rail standards like ERTMS/ETCS is given.