Using space imagery in the rail sector

If you think space research is a scientific field far removed from down-to-Earth issues, think again! Carole Desnost, SNCF’s Chief Technical Officer Technologies, Innovation and Group Projects, and Lionel Suchet, Chief Operating Officer of CNES, France’s space agency, have signed a partnership agreement that aims to continue the collaboration that began back in 2016. How can satellite data help improve rail services? What main areas can it be used in? Stéphane Callet answers these questions.

We want to leverage the potential of space technologies and services to improve our rail system. Concretely, SNCF Group will set up a monitoring committee made up of representatives from its different companies to facilitate and coordinate shared initiatives. These SNCF committee members will work with their counterparts at CNES, and bring in other people as necessary—e.g., for in-depth inquiries into specific issues, or joint research projects and programmes. The partnership also gives SNCF access to the latest in space advancements from French and European teams. We can also refer specific challenges to CNES, and spotlight relevant rail case studies so these can be factored into its space research efforts.

Our agreement targets three key areas: Earth observation, telecoms (train–infrastructure connectivity), and “navigation” (geolocating trains and objects). Satellites give us invaluable images that help us understand events on Earth's surface.

Optical and near-infrared images help us classify different types of trackside vegetation and determine their hydric state, i.e. their water content. This, in turn, lets us assess whether vegetation is too dense, too dry, or even dead, which can pose a fire hazard.  Earth observation satellites also use interferometric radar technology1, which allows us to study surface deformation over large areas with high precision. For example, it can help us anticipate landslides and protect our infrastructure to mitigate their impact. Some satellites carry lowest frequency radars (L band) that can provide crucial information about the water content in the first metres of sub-soil. This data is essential to assess landslide risks that could affect our earthworks.

Events like slow landslides that affect banks, or subsidence in large rubble embankments that can impact tracks. We also monitor changes in land use and land cover—vegetation, crop farming, urban development, etc.—that could destabilize our engineering structures. By combining satellite imagery with data on crop types, crop rotation, and seedling and furrow orientation, we can identify new zones in our network that are vulnerable to runoff during heavy rainfall.

Heavy rainfall can compromise the soil supporting our infrastructure, causing train service disruptions that may last from a few hours to several weeks. Thanks to space data, we’ll be able to take special measures to prevent landslides and monitor these locations very closely. On days when storms are forecast by Météo France, we might even cap train speeds, etc. Adapting the SNCF Réseau network to climate change is a key focus of our collaboration agreement with CNES.

Satellite communications (SATCOM) give us near total telecoms coverage, even in dead zones such as remote rural areas or valleys in mountainous regions. The potential application is better data transmission connections with trains by combining cell towers with satellites. It also opens up the possibility of integrating connected devices, or IoT technology.

There are lots of ways connected devices might deliver, depending on which sensors they use. A device equipped with a heat or smoke detector, for instance, could identify wildfires close to tracks. And if a wildfire started in an area with no 3G or 4G network coverage, autonomous trackside sensors could alert the local fire and rescue service, government transportation agency, and any other body responsible for responding to wildfires. Smart devices can also include sensors installed on fixed rail infrastructure, such as tracks, or installed on board rolling stock, such as trainsets and wagons, to help manage our physical assets. SNCF Réseau and SNCF Voyageurs both play an active role here, and it’s an area where CNES—which has proven its ability to find solutions—can help SNCF tremendously.

For data and voice transmission, that’s the aim of the EU’s IRIS 2 programme for secure, sovereign connectivity. IRIS 2 will employ a constellation of nearly 300 satellites. The system is designed to provide secure, resilient communications for critical services such as firefighters, the army and the police. But we could also see it being used for rail operations—for example, to communicate with employees in the field or to link different pieces of equipment. Satellite systems offer us a host of solutions, and this partnership will keep us on the cutting edge, where we can keep track of the latest solutions and emerging space programmes to gauge their usefulness in our rail operations.

It will. The best example is the most obvious field of application: navigation. To augment the US’s GPS system and Europe’s global navigation satellite system, Galileo, the European Space Agency has launched EGNOS (European Geostationary Overlay Service) for aircraft. EGNOS is a Safety-of-Life (SoL) navigation service that makes aircraft location data more accurate and secure. We are currently testing an EGNOS system for rail that enhances train location information using satellites—and thus delivers the security required for the new European rail signalling system, ERTMS. Apart from these European applications, the sheer precision we can achieve with satellite services will allow us to explore numerous applications in France, including infrastructure monitoring with STC². It could also prove useful for more specific functions, such as rapidly recharging battery-powered trains.

This partnership brings together teams at CNES and SNCF to discuss where technology is heading in space—with IRIS 2, EGNOS, and Copernicus—and in rail, with programmes like ERTMS and the STC. It might also lead to other joint efforts if our teams come up with ideas to tackle issues we both face. Just like our work alongside industry partners, this agreement allows us to join forces with an agency that has a bird’s eye view of innovative emerging technologies. CNES also has a channel for sharing its expertise with commercial companies, via Connect by CNES and its R&T research and technology programme.