USE OF COMMUNICATIONS TECHNIQUES IN A FUTURE TRAIN AND LINE SYSTEM

The task of communications techniques is not only the transmission of information from one source to the user, but also the processing of this information according to scheduled programs. In transportation safety, the initial information in the form of an oral instruction or a programmed coded order must be transmitted to the vehicle and received by it. From the communications standpoint, it is necessary to differentiate between, (1) one-way transmission from train to track or from track to train, and (2) two-way transmission between track and train. In one-way transmission from train to track, direct current circuits are generally used, together with axle counters. Two-way communication between track and train can be accomplished by superimposing both transmission directions onto a closed circuit. The planning of a linear safety system begins with the desired speed-related headway interval. Three safety systems are described and the economics of expenditures on train and track are discussed with particular reference to the wide variety of signalling tasks on the one hand, and the relationship between the length of line and the quantity of rolling stock on the other. The article describes a digital system, with specially simple vehicle equipment, designed for underground railways.