April 19, 2016

On a high-speed train at night – DLR researchers develop train-to-train communication

In the course of a measurement campaign conducted in Italy by the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) transmission properties between the individual carriages of high-speed trains and the entire train were measured to develop systems that will enable reliable communication. Such systems will be used in the future so that carriages and trains can autonomously connect to – or, when necessary, disconnect from – larger trains whilst in motion. This process is known as 'dynamic coupling' or 'virtual coupling'.

With virtual coupling, the trains are not connected physically but via a wireless communication link. This has in many cases the advantage that passengers will be able to reach their destinations in a shorter period of time and without having to change trains. In addition, the capacity limits of railway lines can be increased without the need for additional infrastructure. In order to be able to analyse different scenarios, the researchers installed communications and navigation technology throughout the train. For example, DLR scientists fitted directional antennas at the head (nose) of the train for virtual coupling measurements.

Night runs between Naples and Rome

In order to carry out their measurements, the Italian rail company Trenitalia provided DLR researchers with two Frecciarossa high-speed trains during the nights from 15 to 19 April. With these trains, the researchers were able to run through various scenarios and manoeuvres in order to investigate communications between and within the trains. Stephan Sand, Team Leader of the Vehicular Applications Research Group at the Institute of Communications and Navigation, was excited to test the systems developed by the Institute and carrying out the measurements on the high-speed trains with their partner Trenitalia. "The railway between Naples and Rome is particularly well suited for this because it offers both the possibility of carrying out measurements in an urban area at low speed and demonstrating that our systems function just as reliably at very high speed." The preparations started late in the evening each day, as the lines for the measurements were available at night and the trains were used again for public passenger transportation on the next day.

On board: Railway Collision Avoidance System (RCAS)

The Railway Collision Avoidance System (RCAS) was also installed on board for train-to-train communication. This communication and location unit, developed by DLR, sends information on the position, planned route, speed and stopping power to every train in the vicinity in real time, thus helping to identify potential conflict situations. The system has already been successfully tested on regional trains in partnership with the Bayerische Oberlandbahn (BOB). The measurement unit could now be used on high-speed trains for the first time in Italy.

Wireless communication between carriages

DLR researchers are also working on modernising the exchange of information between train carriages. Instead of cable-based connections throughout the train, as is the default today, they installed antennas on the roof of the carriages for the test runs. These antennas transferred the information from one carriage to another, via the roofs of the carriages. Modernising the exchange of information between carriages is of particular interest for the Train Control Monitoring System (TCMS). The TCMS controls and regulates various safety-critical functions, which are needed to ensure the safe operation of the train and the safe transportation of people and goods.

Wireless transmission has huge advantages in terms of maintenance and safety: By transferring information via antennas, the cumbersome, cost-intensive cable replacements can be greatly simplified in the event of malfunctions in carriage-to-carriage communication. Head of the DLR measurement campaign, Paul Unterhuber, explains: "For a wireless connection, it is essential that the system functions just as reliably as a cable-based system. If we want to place some of the communication technology on the roof, we need a thorough understanding of the radio wave propagation in that configuration."

The researchers could lay the foundations for wireless TCMS with their measurements in Italy. In order to model the radio channel, the researchers ran through scenarios involving two high-speed trains at various speeds and various manoeuvres such as overtaking and passing in opposite directions, throughout the four nights. The measurement results allow predicting the effects of a particular environment on the transmitted signals. Once the essential characteristics of the radio channel have been determined, they can be used in the development of new, safety-related communication systems. The team to Paul Unterhuber and Stephan Sand therefore investigated the propagation of radio waves in a realistic environment. "With these measurements and our previous investigations of virtual coupling, we hope to significantly improve the exchange of information in and between trains. Another of our aims is to ensure better utilisation of the tracks," explains Stephan Sand.


The measurements in Italy were carried out as part of the European Union (EU) Roll2Rail project. Roll2Rail is one of the lighthouse projects of Shift2Rail within the Horizon 2020 programme. Thirty-one European partners are working on the development of key technologies, increasing reliability in the railway sector and reducing costs. The Roll2Rail project has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No 636032. The project is closely connected to the DLR Next Generation Train project.

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Dorothee Bürkle

German Aerospace Center (DLR)
Media Relations, Energy and Transport Research

Stephan Sand

German Aerospace Center (DLR)
Institute of Communications and Navigation
Münchener Straße 20, 82234 Oberpfaffenhofen-Wessling

Julia Heil

Editorial management DLRmagazine
German Aerospace Center (DLR)
Communications and Media Relations
Linder Höhe, 51147 Cologne