INNOVATION BRINGS SATELLITE-BASED TRAIN CONTROL WITHIN REACH
Gbegbe Raymond, Juliette Marais, Marion Berbineau · Railway gazette international · 2004
This article discusses the use of global navigation satellite systems in communications-based train control (CBTC) in place of conventional signalling. CBTC relies on continuous updating of train location, which can be provided by satellite navigation. This can reduce or eliminate the need for balises. A critical objective of CBTC is to optimise the braking curve which needs adequate accuracy and full integrity. The completion of a network of satellite systems provoked interest in using it for train control: however, concerns exist about the accuracy, integrity and reliability of the signals, and about relying on outside parties. Signals reflected from or masked by buildings or other objects can falsify position calculations, and system designers must weigh the cost of integrating additional sensors against their contribution to overall accuracy and integrity. It seems that in Europe a combination of satellite and other positioning systems offers greatest flexibility.