business applications

RailSAT - Monitoring Railway Track Geometry and its Surroundings

With ever increasing rail traffic, asset managers are consistently challenged to improve the performance of the railway network. Both availability and reliability of rail tracks are key concerns and need to be maximised in order to optimise operational efficiencies and ensure safety. Accurate monitoring is a key enabler for effective maintenance operations that include, for example, of tamping, rail track condition and track-works. The most desirable outcome is to achieve continuous monitoring of the entire network. This can be achieved through the strategic exploitation of wide area satellite data to identify hotspots for more intense monitoring activity. Furthermore, this activity underpins a more effective analysis and understanding of track behaviour as well as identifying the possible effects from changes in the surrounding environment. 

Expected Added value: The RailSAT service has the potential to deliver significant ongoing savings in maintenance costs with minimal upfront investment costs. This is achieved through the use of satellite data to enable continuous monitoring of the entire network and the targeting of hotspots for more intensive monitoring. 

Users and their needs

Three main customer/user segments are involved in the maintenance of railway infrastructure: 

  • Asset managers: Day to day maintenance of railway infrastructure is the responsibility of the national railway authorities, who act in the role of asset managers/owners. They are required to continuously monitor the whole network and to take appropriate measures to ensure operations and safety. 
  • Service providers: In several countries (e.g. the Netherlands, Sweden) the role of the asset managers in maintenance planning and execution is outsourced to service providers/contractors. 
  • Engineering companies: Asset managers use the advice of engineering companies for some of the technical issues, such as advising on appropriate measures to ensure operations and safety.  

Currently, railway infrastructure is inspected both visually as well as by dedicated video and measurement trains that monitor the condition of the railway network. Based on this information, track maintenance operations are planned and executed. The disadvantages of this current approach are the low frequency of both, measurement trains and visual inspections.  This is due to the relatively high costs of increasing the frequency of these types of operations. 

Stakeholders are therefore looking for a solution that can provide monitoring of the entire network on a more frequent basis. In order to achieve this, a solution that is nonintrusive, has readily available data, can improve existing prediction models and does not need major investment in new assets or infrastructure is highly desirable.

The country/countries of the targeted users are:

Targeted users are based, initially, in the United Kingdom, the Netherlands, Germany, France, Spain, and Sweden. The service will eventually be extended across the whole of Europe.

Service/ system concept

Service Concept 

The RailSAT service provides continual monitoring at a regional level through the exploitation of Sentinel-1 InSAR data to provide wide–area ground deformation rates and identify hotspots. The identification of these hotspots informs the need for more intensive monitoring. 

By using a step by step approach several types of analyses are possible: 

  1. Regional analysis to qualitatively investigate overall terrain deformation trends such as slow-moving landslides, mining-induced subsidence or uplift, etc. that may have an impact on the track or corridor. 
  2. 50-100 m corridor & wide-area analysis to quantitatively investigate overall large scale terrain movement and correlation with geotechnical data (risk assessment of earthworks, landslides, mining, etc.) 
  3. 10-25 m corridor analysis to investigate track substructure deformation and stability (risk assessment of subsoil/transition points/culverts/viaducts/level crossings etc.) 
  4. 3-5 m corridor analysis to investigate deformation of individual tracks and correlation with other track geometry measurement data (risk assessment of individual tracks and the impact of tamping)

System Concept 

As the theoretical position of the track axis is known, deformation (rates) within the corridor of individual tracks can be analysed and compared/combined with data obtained from measurement trains. Both the vertical deformation of the track alignment in time as well as exceeding local displacements within shorter periods can then be examined.

Space Added Value

Satellite monitoring offers a solution which provides asset managers and infrastructure owners with services that cover the total network, is non-intrusive, already has historical data available, can improve existing prediction models and does not need new data acquisition tools/equipment. 

Satellite-based InSAR data is available in a much higher frequency of every 4 to 12 days. If this EO data source can be used as an additional indicator for monitoring track behaviour, this can supplement the existing methods and overcome their weaknesses. 

Interferometric Satellite Aperture Radar (InSAR) techniques make use of Synthetic Aperture Radar (SAR) datasets derived from Earth observation satellites. SAR is an active microwave imaging system and used because it provides all-weather and cloud penetrating capabilities around the clock. 

This service will use data sets such as ERS and Envisat to provide baseline land deformation surveys as well as Sentinel-1 images to provide dynamic baseline surveys of wide area land deformation. This synthetic aperture radar asset provides near-global coverage on a 6-day acquisition frequency.

InSAR requires the availability of sets of satellite images with the same properties, so-called ‘stacks’. The above figure shows some of the larger stacks in the UK with over 20 images. Every 12 to 24 days, images are added to the stacks. 

RailSAT uses existing satellite navigation systems such as GPS and GLONASS to provide stable reference position for the InSAR data and to provide accurate positioning for maintenance trains. Improvements in positioning accuracy and integrity will be made possible through the use of EGNOS and Galileo early services. 

Current Status

The project started with a kick-off in the UK in the offices of Network Rail and a first discussion with potential users of Network Rail. 

A first stakeholder meeting with EIM, SNCF, DB, ADIF, SBB and HS2 took place on 30 January 2017 at ESA’s Headquarters in Paris. A second stakeholder meeting took place on 9 March 2017 in Brussels.

Interested stakeholders are invited to contact Mr Henk Samson (Strukton Rail) for information about how to engage with the project.

Project Managers

Contractor Project Manager

Henk Samson
Strukton Rail, Westkanaaldijk 2,
3542 DA Utrecht

ESA Project Manager

Christian Walter
European Space Agency, European Centre for Space Applications and Telecommunications Fermi Avenue, Harwell Science & Innovation Campus,
OX11 0FD
United Kingdom

Status Date

Updated: 22 June 2017 - Created: 22 June 2017