A new electronic railway signalling system to avoid accidents, specially in mountainous regions, has recently been developed by Indian scientists. Unlike the conventional systems currently employed by the Indian Railways, this new signal uses technology that allows a bi-directional flow of information between a running train and the control unit. The technology, proposed by researchers at Maulana Abul Kalam Azad College of Technology in Bhopal, India, relays messages via a system of infrared transmitter-receivers located on the trains' roofs and the signal posts. It incorporates a microprocessor, a visual display unit, a voice messaging system inside the train and a special digital camera mounted on the train's roof that monitors the tracks and relays suitable signals (PTI Science Service , Vol 17, No 3).