Cost effective railway signalling by wireless communication among onboard controllers and switch controllers

The signalling system is one of the most costly systems in the railway infrastructure. The cost of the trackside controllers is particularly high because high-performance failsafe hardware and software are needed to supervise and control the many pieces of the field equipment. A signalling system is described that has a lower projected cost because of the application of the traditional token block mechanism to the virtual blocks dividing each controlled section. Its basic mechanism is the sharing by the wireless communication of the information about the exclusive rights with the virtual blocks, the status of the switches and the instructions for controlling the switches in the controlled section among the onboard controllers and the switch controllers, respectively. A telegram for each controlled section is circulated in turn among these controllers for the sharing. This mechanism provides an automatic train protection and an interlocking function without using the trackside controllers. Its application to a very high-density line might reduce the train operation density because of the telegram circulation time, but the reduction would be no greater than 20% on the highest density line if the current radio technology was used. A cost evaluation based on a 20-km double-track line showed that this system is about three times more cost effective than the communication-based train control system.