The Auxiliary Anti-Collision Scheme of Urban Rail Transit Based on CSS

In normal circumstances, the safety of metro train operations is guaranteed by the automatic train protection system (ATP). When the ATP system becomes ineffective, train operations are in degradation mode. In order to ensure the safety of the metro trains, the auxiliary anti-collision scheme, which is based on broadband wireless ranging technology CSS (chirp spread spectrum), can provide the real-time distance detection between the successive running trains and the alarm information of dangerous distances between trains. The paper firstly elaborates the structure, key technology and working principles of the scheme. Furthermore, the design of the ranging unit is presented. Finally, a distance measurement experiment has been completed in a subway tunnel. The test results show that this scheme can provide real-time, accurate distance information between successive running trains. The scheme can achieve safety warning requirements.