Publié le 20/05/2016 - Mis à jour le 23/05/2017
Passer la zone des réseaux sociaux

Surveillance Train – train track conditions in real time

A buzz in the air can be felt in the North Star building located near the Gare du Nord railway station in Paris. A group of managers is expecting a foreign delegation which has expressed a very strong interest in in the Surveillance Train. This train is an innovative and highly effective device for the automated surveillance of train tracks.

One morning in January 2016…

Three visitors in charge of railway network maintenance in a neighbouring country arrive at reception. They are coming to discover the new automated train track surveillance system developed by SNCF Réseau.

The visitors are met by Pascal Guillaume, Deputy General Manager for Engineering and Projects, and by two managers of the Train Track Maintenance Division, which plays a key role in the surveillance system: Yves Fourdin, Division Head and 
Lionel Verdier, a maintenance expert.

A visit by European counterparts who are interested in finding out more
about the new automated train track surveillance system developed by SNCF Réseau.

Train track surveillance

Close-up view of a train track

In the conference room, Yves begins his presentation of the Surveillance Train.

Yves explains that the Surveillance Train is one of the main tools in the Vigirail surveillance and network maintenance programme, which was initiated in October 2013. This is a detection and automated measurement system used for the different components of the railway line. “We have three self-propelled approved devices to operate on the railway line. They travel on the railway lines just like commercial trains and are even part of them. In fact these Surveillance Trains are ordinary diesel locomotives, but which are equipped with twelve high definition cameras to provide a 3-D image of the train tracks on control screens. These locomotives also have very powerful onboard computers which are capable of collecting and analysing thousands of information elements per second.”

Twelve high definition cameras provide
a 3-D image of the train tracks

Yves continues his presentation: the three Surveillance Trains travel every day over the 50,000 kilometres of the French railway netwxork. They examine the train tracks on the major railway lines on which traffic is very dense and whose component parts are sufficiently uniform to be analysed. “This accounts for about 1/3 of the national railway network”, says Yves.

The scheduling of this train surveillance is organised once a year as it requires considerable preparation beforehand. Surveillance Trains can only operate during the day and must be inserted into the existing traffic despite their maximim speed of 80 km/hour. “Safety considerations are very important”, explains Yves. In 2016 15,000 km will be examined by the three Surveillance Trains. 

This surveillance is organised once a year as it requires considerable preaparation beforehand.


An indispensible complement to visual on foot inspections

While Pascal Guillaume highlights the quality of the surveillance system’s observation and automated detection as well as its reliability, one of the members of the delagation asks a question. “Nevertheless you did decide to keep on foot visual inspections, as we do with our own system?”

Pascal confirms this point: “Yes, because automated surveillance does not replace visual inspections, it is simply complementary. It is now possible for viusal inspections to focus on very specific types of observations, for example switches, the surrounding vegetation, level crossings, land infrastructures, etc.”

Automated surveillance does not replace visual inspections.

Yves contines his explanation: “Without a doubt, this concentration of technology saves a considerable amount of time. Instead of spending an hour on a 3 km visual inspection on foot, we can do 80 km with the train. Having said that, it will never replace the human eye!”.

Instead of spending an hour on a 3 km visual inspection on foot, we can do 80 km with this train.


Going to Nancy on a Surveillance Train

The Surveillance Train

The next day, with daylight barely breaking.

The group meets in front of a small orange and black train on one of the service platforms at the Paris-Est railway station.

Lionel points out to the visitors that the Surveillance Train has a diesel engine to allow it to operate in areas where the railway lines are nor electric.

The participants are invited to board the train by the four memebers of the crew:

  • Train foreman
  • The driver, who has a pefect knowledge of the area where the detection operations will be conducted
  • Two operators – one in charge of onboard observation and the other who is responsible for the processing of the results
thousands of kilometres to monitor


The train starts to leave.

There is no time to lose. The Surveillance Train must be at the observation area in one hour. Yves shows the visitors the three onboard computers. Real-time images will soon appear on the screens. These images are compartmentalised and are displayed in different categories:

  • Fastenings (to attach the track to the railway sleeper)
  • Ballast level (rocks)
  • Train track surface
  • Spice bars (metal parts which connects two consecutive tracks)


Optimal reaction times

Now that it has reached the area to be inspected, the Surveillance Train is operating at its maximum speed. Images of an excellent quality are appearing on one of the screens in real time. “Our measurement instruments are very sensitive so the computers will not miss any problems. Any irregularity will be displayed on this other screen and the operator will decide whether to notify the control centre or to take no further action regarding the detection”.

The operator adds: “When an irregularity is detected, there is an immediate notification to schedule a maintenance operation on the track as soon as possible in order to make the repair.”

The Surveillance Train has now been scrutinising the train track and its surrounding area for an hour.

Lionel continues his explanation: “Collected data enables us to check the height of the ballast (30 cm), the position of the railway sleepers (one every 60 cm) and the track gauge (140 cm), etc.”

Yves then adds: “The data which is confirmed by the operator is stored in a software application called SILVIA (surveillance of train tracks via automated inspection). After the data has been entered in the system, it is available to all SNCF Réseau employees in the field. In fact, it is these employees who determine the maintenance actions to be taken or the possible works that may be performed. Depending on the problem which has been detected, appropriate maintenance or railway works are undertaken within the coming hours or days …”

SNCF Réseau employees working in the field determine the maintenance actions to be taken or the possible railway works to be performed


After a half day of observation, the Surveillance Train arrives in the railway station in Nancy.

This time the train did not detect any significant irregularity in the area it covered. The three visitors will return to Paris and then to their home country. It would not be surprising if they recommended the adoption of the Surveillance Train to improve their railway network surveillance and maintenance system! Only time will tell …