In a series of trials, the automotive electronics industry recently demonstrated that it is possible to connect multiple trucks to a platoon by means of nothing but an electronic information link. A similar technology is currently under development for high-speed trains.
In railroad environments, the technology is called Virtual Coupling: Single railcars or multiple-wagons join together, forming one train. This enables railway operators to dynamically create long-distance trains; the wagons can join and leave the train if required by the respective journey. The benefit: Passengers can reach their destination without changing trains, which can save them time. In addition, the track utilization can be increased without the need to modify the infrastructure.
In such virtual trains, the components are not coupled physically to each other but instead through a wireless communications link. In the course of the development works, the German Aerospace Research Center (DLR) recently surveyed the transmission characteristics of such wireless links between wagons of high speed trains as well as between complete train formations to ensure reliable communications. The measurement works were executed between April 15 and April 19 on two high-speed trains of the Italian railroad company Trenitalia. The configuration allowed the DLR researchers to perform several scenarios and manoeuvres and thus investigate the transmission properties. The stretch between Rome and Naples is particularly well suited for such measurements, because there we had the possibility to perform measurements at low speed in urban spaces, and we could prove that our systems work well during a high-speed ride, explained Stephan Sand who oversees the land traffic section at DLRs Institute of communications and navigation which developed the measurement setup.
The communication system included the Railway Collision Avoidance System (RCAS), a DLR-developed system that transmits real-time data including position, planned journey, speed and brake capabilities to all trains in the surrounding and thus contributing to identify potential conflicting situations. The system has already been tested in regional trains; the experiments between Rome and Naples were the first time the system was applied in high-speed trains.
Part of the project was to modernize the information exchange between the wagon of the train. Instead of a wirebound connection over the entire length of the train as it is the case with todays railway technology, the DLR experts installed antennas on the roofs of the wagons. These antennas radioed the data from each wagon to the next one across the roofs of the cars.
The modernization of the data exchange between the wagons is relevant for the Train Control Monitoring System (TCMS). This system controls multiple safety-critical functions required to guarantee the safe operation of the trains.
The wireless technology applied also offers enormous advantages in terms of maintenance and reliability. With the existing technology, the cabling has to be replaced in the case of a malfunction a complex and cost-intensive process. The propagation of the radio waves in the difficult high-speed train environment is however not a trivial thing either. Therefore, extensive measurements are necessary to create the technological foundation for future wireless approaches. To characterize the properties of the radio connections, the scenarios investigated passing and encountering. The results of the measurements enable the scientists to predict the behavior of the signal in varying environments.
The measurements were performed in the context of the EU project Roll2Rail, a flagship project within the Shift2Rail initiative which involves 21 European partners. The goals include developing key technologies for future railway traffic and increase safety and reliability of technologies utilized in this type of traffic.
