Communication, navigation and surveillance: essential functions for trains

Science topics July 2019 TransportInnovationEnergy

By Marion Berbineau, senior researcher, Juliette Marais, researcher - COSYS Department, LEOST Laboratory

The rail network must be modernised to meet the societal, environmental and technological challenges ahead. The necessary changes will involve communication, navigation and surveillance systems. IFSTTAR, with its partners, is involved in the development and management of these new technologies to enable autonomous driverless trains to operate safely by 20231.


Train-borne communications and location-tracking technologies

The reception of GNSS signals in a railway environment impairs localisation performance.
Communication, navigation and surveillance: essential functions for trains - Ifsttar - Reception of GNSS signals - crédits Ifsttar

The railway network2 is divided into sections called blocks. These portions of the track are equipped with balises that are physical today and that will be virtual tomorrow. These balises detect when the train enters and exits the block. The block therefore provides a safety bubble around the train. To do this, it restricts access to a block to a single train and thus prevents collisions between two trains that are following each other at different speeds.

Today, when the train enters the area, it communicates with the infrastructure by means of a track-to-train radio system. A short- range radio beacon also informs the train of the current speed limit as well as that on the next block and its position. This track-to-train radio system is vital for the safe management of rail traffic.

In the very near future, there will no longer be any physical balises or beacons to delimit the block, detect the presence of the train and transmit speed instructions. Everything will be based on on-board wireless communication and localisation technologies. This will drastically reduce the costs of infrastructure deployment and maintenance (only the rails will be fixed to the ground). In addition, it will improve the flexibility and efficiency of traffic management: the blocks will be of variable length and move with the train. This is the concept of the moving variable block.

To continue to guarantee traffic safety, the train's position will have to be known with great confidence and radio communication will have to be robust in all train environment conditions.


Supervising and operating driverless trains

The next revolution, starting in 2023, will be the introduction of driverless trains on the rail network. As with air transport, this requires the intelligent and safe combination of the three essential functions: communication, navigation and surveillance.
The radio communication system will have to adapt in real time according to the radio networks available in its environment. It will evolve seamlessly with emerging technologies such as 5th generation mobile networks (5G NR).
The train control-command system must be able to trust the train position information it receives regardless of the geographical environment and the presence of interference. This information will be based on a combination of technologies: satellite-based (GNSS), inertial systems, Ultra Wide Band (UWB) systems or based on  future radio communications systems when the train is in a tunnel.
To guarantee the safe operation of driverless trains, the train must be equipped with short- and long-range perception systems (as is the case with autonomous road vehicles). These anti-collision RADARs, cameras and LIDARs will have to operate both day and night. They will transmit real-time information on the tracks and the train environment even at very high speeds (obstacles on the track, level crossings, etc.)



1 SNCF Press release
2  “A rail network is a set of railway lines, stations and technical facilities (workshops, depots, marshalling yards, private sidings, intermodal hubs, etc.) that allow  trains to travel in a given geographical area, whether a region, a country or a continent. ” Wikipédia




Find out more..

Marais, J., Beugin, J, Berbineau, M., 2017, A Survey of GNSS-Based Research and Developments for the European Railway Signaling, IEEE Transactions on Intelligent Transportation Systems, Institute of Electrical and Electronics Engineers - IEEE, 17p, DOI : 10.1109/TITS.2017.2658179,,

Berbineau, M. ; Kassab, M. ; Gransart, C. ; Wahl, M. ; Cocheril, Y. ; Masson, E. ; Seetharamdoo D. ; Sanz, D. ; H. Ghannoum, H. ; Gatin, O. ; Le véhicule connecté dans les transports publics : technologies existantes et perspectives, REE N° 4, 2014

Berbineau, M., Kassab, M., Gransart, C., Wahl, M., Marais, J., Seetharamdoo, D., IET, Clean Mobility and Intelligent Transport Systems, Chapter 3: ICT for Intelligent Public Transport Systems, state of knowledge and future trends, 2015, ISBN 978-1-84919-895-0

Marais, J ; Cherche GPS fiable pour train autonome, Trajectoire N13 juin 2017