# Rail infrastructure monitoring with satellite data Satellite data cover a whole rail network at once. Optical images show how vegetation grows along the tracks, radar measures ground deformation, subsidence and landslide movement under the line, and flood maps show where the line is exposed to flooding. Infrastructure managers use the results to decide where to inspect and maintain first, instead of checking every kilometre on site. ## Who needs it Rail infrastructure managers maintain long networks across varied terrain, geology and climate. Inspecting large networks on site is costly, and for monitoring ground stability at network scale, local methods such as LiDAR may be too expensive because they need extensive measuring networks [2]. Satellite data work at this scale. EUSPA describes how satellite imagery identifies vegetation levels and their proximity to the tracks as well as ground deformation and subsidence across a network, so that problems can be tackled before they escalate [1]. Solutions based on Earth observation and GNSS support the monitoring of track deformation at network scale and the assessment of natural hazard risks while reducing the cost of on-site inspections; continuous monitoring enables a move to predictive maintenance, and ground-motion and vegetation monitoring by radar interferometry is increasingly integrated into operational infrastructure management [1]. ## What satellite data can measure along a line - **Trackside vegetation**: Copernicus Sentinel-2 images have a resolution of 10 m and a revisit time of five days [3]. Vegetation indices such as NDVI, calculated from red and near-infrared light, show vegetation density and changes in plant health [4]. A time series shows where vegetation grows towards the line. - **Ground deformation**: radar interferometry provides millimetre-scale measurements of the subsidence and landslides that affect railway lines, and the European Ground Motion Service provides these data free of charge [5]. How it works is explained in [monitoring ground motion with InSAR](https://leto.space/use-cases/ground-motion-insar/). - **Flood risk**: the European Flood Awareness System produces probabilistic flood forecasts with lead times of up to ten days, and its notifications go to national, regional and local authorities [7]. Flood hazard along a line can be mapped in advance, as in [mapping flood risk](https://leto.space/use-cases/flood-risk-mapping/). Radar satellites such as Sentinel-1 acquire images day and night and through clouds [8], so ground motion monitoring does not depend on the weather. **Figure:** Illustrative map, not real data. A railway along a river, with ground motion measured by radar on the track and nearby buildings. ## How it works 1. **Define the corridor**: the lines to monitor and a buffer on each side of the track. 2. **Build the layers**: a vegetation time series from optical images, ground motion points from radar, and hazard layers for floods and landslides. 3. **Set thresholds**: for example vegetation within a distance of the track, or movement above a rate in millimetres per year. 4. **Rank the sections**: each section of the line gets a priority from the layers it crosses. 5. **Inspect and maintain**: crews go first to the sections at the top of the list, and their findings flow back into the thresholds. Satellite data complement the measurements the railway already makes. In-service trains equipped with sensors increasingly monitor track geometry, linked with GNSS for accurate location [1], and drones equipped with GNSS deliver high-resolution imagery of catenary lines, track geometry and vegetation; RFI in Italy, for example, integrates drones and GNSS to monitor catenary and track geometry [1]. ## What you get - a map of the network with sections ranked by vegetation, ground motion and hazard - time series of vegetation and ground motion for each section - alerts when a section crosses a threshold you define - a basis for planning vegetation cutting, inspections and maintenance in a predictive way [1] ## Limits **Limits** - **10 m is coarse next to a track:** A free Sentinel-2 pixel covers 10 m by 10 m \[3]. It shows vegetation trends along a corridor, not a single tree leaning towards the overhead line. That needs very high resolution images, drones or a visit. - **Clouds hide optical images:** Vegetation monitoring relies on optical images, which clouds can hide. Radar works through clouds \[8], but it measures ground motion, not plant health. - **Ground motion data are not real time:** The European Ground Motion Service is updated once a year \[6]. Sudden events such as a fast landslide need sensors on site and warning systems. - **No view of the track itself:** Satellites do not measure track geometry or the condition of rails, sleepers and switches. That stays with measuring trains and inspections \[1]. ## How we help Network-wide monitoring changes how inspections are planned, so it has to fit the maintenance process. In a [strategy engagement](https://leto.space/consulting/strategy/) we check which risks along your lines satellite data cover best. We then write the requirements: layers, thresholds, update rate and the interface to your asset management system. [More on requirements and procurement](https://leto.space/consulting/procurement/) The marketplace on [Spacegraph](https://leto.space/spacegraph/), our discovery platform, has a use-case category for infrastructure integrity and an industry category for transport and logistics. ## Related use cases - [Monitoring ground motion with InSAR](https://leto.space/use-cases/ground-motion-insar/): How radar satellites measure millimetre movement of the ground. - [Monitoring pipelines and grid corridors](https://leto.space/use-cases/pipeline-corridor-monitoring/): Vegetation and ground motion along energy routes. - [Monitoring global traffic hubs](https://leto.space/use-cases/traffic-hub-monitoring/): Ports and hubs that a supply chain depends on. - [Mobility and logistics](https://leto.space/industries/mobility-and-logistics/): Use cases for road, rail, aviation and maritime transport. ## Frequently asked questions ### Which satellite data help monitor vegetation along railway lines? Satellite imagery helps identify vegetation levels and their proximity to the tracks at network scale [1]. Copernicus Sentinel-2 provides free images with a resolution of 10 m every five days [3], from which vegetation indices such as NDVI show the density and health of plants [4]. Single trees close to the track need very high resolution images or drones. ### How often is the data updated? It depends on the layer. Sentinel-2 revisits every five days [3], but clouds can hide individual images. The European Ground Motion Service is updated once a year [6], which suits slow movements such as subsidence, not sudden events. ### How do we start a pilot? Choose one line or one region with known problems, such as vegetation incidents or a slope that moves, and compare the satellite results with your inspection records. This shows what the data add before you extend them to the network. Our [consulting overview](https://leto.space/consulting/) shows the path from the problem to operation. ## Sources 1. [EU Space Market Report 2026, Issue 1, EU Agency for the Space Programme (EUSPA), 2026-05-26](https://www.euspa.europa.eu/sites/default/files/documents/EU_Space_Market_Report_2026.pdf) 2. [EUSPA EO and GNSS Market Report, Issue 2, 2024, EU Agency for the Space Programme (EUSPA), 2024](https://www.euspa.europa.eu/sites/default/files/external/publications/euspa_market_report_2024.pdf) 3. [Sentinel-2 (mission page), European Space Agency (ESA), accessed 2026-10-06](https://www.esa.int/Applications/Observing_the_Earth/Copernicus/Sentinel-2) 4. [Landsat Normalized Difference Vegetation Index, U.S. Geological Survey (USGS), accessed 2026-10-06](https://www.usgs.gov/landsat-missions/landsat-normalized-difference-vegetation-index) 5. [Tap into Europe in motion (European Ground Motion Service), European Space Agency (ESA), 2022-07-26](https://www.esa.int/Applications/Observing_the_Earth/Copernicus/Sentinel-1/Tap_into_Europe_in_motion) 6. [European Ground Motion Service (product page), Copernicus Land Monitoring Service, accessed 2026-10-06](https://land.copernicus.eu/en/products/european-ground-motion-service) 7. [Observer: How the EU Space Programme supports flood preparedness, the role of the European Flood Awareness System (EFAS), EU Space Programme (Copernicus Observer), 2025-01-29](https://eu-space.europa.eu/news/observer-how-eu-space-programme-supports-flood-preparedness-role-european-flood-awareness-system-efas) 8. [Sentinel-1 mission… did you know?, European Space Agency (ESA), 2025-11-03](https://www.esa.int/Applications/Observing_the_Earth/Copernicus/Sentinel-1/Sentinel-1_mission_did_you_know) Page: