Track circuit

Abstract: The cab signal and rail navigation systems of a railway locomotive are combined to form a single integrated system capable of acting as an automatic train protection system. The train travels along a railway route equipped with a wayside signaling system that features a multiplicity of wayside signal devices. Each wayside signal device provides to the cab signal system a cab signal inclusive of signal aspect information as to how the train should proceed along a particular segment of the railway route. When the train is traveling on a segment of track from which the cab signal is available, the cab signal system receives the cab signal via the AC track circuit disposed on the rails as the train approaches each wayside signal device. After filtering and decoding the electrical cab signal, the cab signal system communicates the deciphered signal aspect information to the rail navigation system. The rail navigation system determines whether signal aspect information should be available from the particular track segment the train is encountering and thus whether and how the brakes of the train will be operated thereon should the train engineer be required and fail to operate the brakes according to one or more braking profiles calculated by the system. The integrated system operates as an automatic train protection system whether the wayside signaling system provides cab signal coverage continuously or noncontinuously throughout the railway route.

Abstract: A train control system includes a control module that determines a position of a train using a positioning system and consults a database to determine when the train is approaching a portion of track monitored by a track circuit. When the train is near a track circuit, but while the train is still far enough away from the track circuit such that the train can be stopped before reaching the portion of track monitored by the track circuit, the train transmits an interrogation message to a transceiver associated with the track circuit. When the track circuit receives the interrogation message, a test is initiated. The test results are transmitted back to the train. The train takes corrective action if the track circuit fails to respond or indicates a problem.

Abstract: The High Speed/High Capacity railway lines use the 2 × 25 kV-50 Hz power system. It is supplied at high voltage by dedicated primary lines that can be placed in close proximity to the railway line. In railway traction systems, locomotive power electronic converters and auxiliary systems are important harmonic sources. Resonance phenomena can cause harmonics amplification, with consequent problems as voltages distortion and electromagnetic interference with track circuits and communication lines. Electromagnetic conducted emissions in railway traction systems are strongly related to the equivalent impedance at the pantograph terminals. This paper presents detailed models of the railway system, also including the primary line, with the aim to evaluate the impact of the primary line on the equivalent impedance seen by the rolling stock, with particular regards to its resonance frequencies.