GPS/GNSS BASED TRAIN POSITION LOCATOR FOR RAILWAY SIGNALLING

Recently, real-time accuracy of the differential Global Positioning System (GPS) receivers achieved submeter level in code mode, and centimeter level in the real time kinematics mode. Thus, GPS receivers became promising for low-cost signaling concepts and other safety critical applications in the railway industry. This paper presents a verification methodology and experimental results of the United States' GPS and Russia's Global Navigation Satellite System (GLONASS) based train position locator tests at Czech Railways. The verification methodology is derived from the current needs in signaling and from the parameters of the satellite navigation systems. A key element in the investigation is a switch, on which reliable and continuous position determination of a routing train is most critical. Two-dimensional (2D) and 1D routing detection models are analyzed and experimentally investigated on the switch point. The trials were performed on the Pardubice-Hradec Kralove-Chocen line with the total track length of 100 km. Three mobile platforms were employed for the tests: an electric locomotive operating passenger train for the long-term locator verification, a diesel track motor-car for tests on a laboratory track in Pardubice station, and a remotely controlled ultralight motor-driven track rover for the detailed locator tests. The data from/to the vehicles were transmitted along the entire trial track though the intelligent 150 MHz Time Division Multiple Access radio modem network with data rate up to 19.2 kb/sec. Finally, the safety-related requirements for the future European navigation system GALILEO are specified and discussed.