Global Navigation Satellite Systems (GNSS) are extremely useful in many different sectors, including transport. Europe declared the initial services of its own GNSS, Galileo, in 2016. It represented an enormous step forward in terms of performance, quality and diversity of service, as well as offering independence and autonomy to its users.

Unlike the United States’ GPS, Russia’s GLONASS and China’s BeiDou (with which, on the other hand, it is interoperable), Galileo is the world’s first GNSS that is designed specifically for civil use and with different user groups and services (e.g. open, high-precision, authenticated, governmental, emergency/search and rescue, etc.) in mind. It also offers unprecedented levels of accuracy and signal quality.

European projects such as RAILGAP, in which Ineco is taking part alongside Adif and CEDEX, build on previous research into the use of GNSS positioning. / PHOTO_MITMA

In the railway sector, GNSS-based applications can be used to optimise logistics, improve the management of rolling stock, and offer information services to passengers. At the same time, they also offer an inexpensive means of improving safety and supervision, by making it possible to replace physical ERTMS (European Rail Traffic Management System) balises with virtual equivalents. Using satellite positioning in conjunction with ERTMS will lower the cost of rolling out a system that the European Commission is currently deploying along the Continent’s main rail corridors –a task being coordinated by Ineco (see ITRANSPORTE 70)–, particularly with regard to regional lines and those with less traffic.

From physical balises to virtual ones

Along with Adif (Spanish Rail Infrastructure Manager), CEDEX (the Centre for Study and Experimentation in Public Works, which is part of MITMA, the Spanish Ministry of Transport, Mobility and the Urban Agenda) and a number of other international partners, in recent years Ineco has taken part in several European innovation projects designed to test and define the use of satellite technology in the railway sector.

To date, the tests that use trains in a real-world setting (such as the tests for the ERSAT GGC project in 2019; see ITRANSPORTE 68) have shown that Galileo is more suitable than the other systems. However, the technology still presents a number of technical hurdles that need to be overcome before commercial solutions can be brought to market. The geography of certain sections of line and the presence of elements such as tunnels, overpasses, natural obstacles and urban areas create so-called ‘shadow areas’ in the transmission of the GNSS signal, which in turn limits the operation of the virtual balises. There are also other problems derived from intentional interference, such as jamming or spoofing. However, the use of other technologies and navigation systems may help to resolve these issues.

The use of GNSS for railway operations depends to a large extent on the nature of the environment. For this reason, it is necessary to classify and identify the factors that contribute to operation under degraded conditions

The RAILGAP (RAILway Ground truth and digital mAP) project, which began in early 2021 and will continue until 2023, is a continuation of earlier research in this field. Part of the Horizon 2020 Programme and managed by the European Union Agency for the Space Programme (EUSPA), RAILGAP is led by the Italian railway infrastructure manager Rete Ferroviaria Italiana (RFI) and boasts numerous participants, including Radiolabs, Hitachi Rail STS, RINA, Trenitalia, ASSTRA, Adif, CEDEX, Ineco, DLR, Université Gustave Eiffel and Unife.

The project’s aim is to develop innovative, high-precision solutions that make it possible to obtain so-called ‘ground truth’ data and digital maps of the railway lines, which are essential in order to determine the trains’ positions efficiently and reliably. ‘Ground truth’ data will provide time-based geographical coordinates for the trains, along with dynamic variables such as speed and acceleration. To achieve this, it will be necessary to gather enormous amounts of train-related data, collected from various types of sensors, which will be used to improve mapping accuracy in ‘shadow areas’ such as urban areas, areas with lots of vegetation or trenches, etc.

The solutions proposed are based on the use of other sensors such as cameras, LIDAR and inertial measurements units, along with artificial intelligence (AI) technologies, to improve the positioning capacity provided by GNSS in ‘shadow areas’. Inertial sensors are used to detect the forces acting on the train, which makes it possible to estimate its movement over time; while optical sensors (cameras and LIDAR), combined with AI systems, make it possible to calculate the train’s position relative to key elements located along the track. In turn, this enables the train to be positioned with pinpoint accuracy, under optimal conditions.

The 30 satellites (24 operational and six spares) that will make up the Galileo system once its full operational capability is reached (initial services began in 2016) will be able to locate receivers with a margin of error of less than one metre. Additionally, Galileo is interoperable with the United States’ GPS, Russia’s GLONASS and China’s BeiDou systems.

RAILGAP will help to make the ERTMS –as well as the monitoring and control systems for the modernisation of regional and local lines– more sustainable, thereby reducing energy consumption.

Ineco is taking part in all of the project’s eight work packages and will lead the process of calculating ‘ground truth’ based on a solution involving the hybridisation of sensors. It also plays a major role in identifying and characterising the optical sensors required by the project, particularly cameras and LIDAR sensors. The activities that comprise work package 7, which focuses on the implementation of the digital map, will also draw on Ineco’s experience in applying AI to images in order to identify key elements, as it has done in other projects for Adif.

To this end, Ineco will develop the algorithms that make it possible to use the images captured by optical and stereoscopic cameras to recognise relevant elements on the track and position them using advanced image processing techniques and AI.

For its part, Adif is also working on all of the work packages, as well as operating a test vehicle (as it did previously for the ERSAT GGC project). The Railway Interoperability Laboratory from CEDEX (which is a world leader in ERTMS; see IT32 and 53) will focus on the architecture of the equipment inside the train and on the data collection phase, as well as the integration of the data in the laboratory.

RAILGAP proposes the use of cameras, LIDAR sensors or inertial measurement units, along with AI technology, to improve GNSS positioning in ‘shadow areas’.

Previous projects

Ineco, Adif and CEDEX have previously taken part in other research and innovation projects with a focus on GNSS applications in railways, such as ERSAT GGC (2017-2019), which also formed part of the Horizon 2020 programme (see ITRANSPORTE 69), and GATE4RAIL (2018-2021), part of Shift2Rail, a sector-specific programme developed by the European Commission to promote innovation in the railway industry.

The aim of the ERSAT GGC project, which involved 14 companies from five European countries, was to study the implementation of satellite technology in the ERTMS using virtual balises. To achieve this, a methodology was defined and several software tools were developed in order to classify a railway line with a view to implementing virtual balises along the length of the track.
The project also included some trials spread across three countries (France, Italy and Spain), where input data was gathered and later fed into the classification tool.

Additionally, 2018 saw the launch of GATE4RAIL, which aimed to improve the virtualisation of ERTMS tests based on satellite positioning. Ineco formed part of the consortium that carried out the project, which was led by Radiolabs (Italy) and also included RFI (Italy), Ifsttar (France), M3Systems (Belgium), Unife (Belgium), CEDEX (Spain), Bureau Veritas Italia (Italy) and Guide (France). Together, the consortium members developed a platform comprised of three blocks: GNSS, train and track. The challenge was to perform a simulation with modules from each block, located in different countries. In this project, which came to an end in 2021, Ineco’s role focused on system architecture and defining scenarios, in addition to providing data on obstacles via the GNSS4RAIL tool.

Challenges facing the use of GNSS in the railway sector

THE TRAIN OF THE FUTURE? A driverless train transporting minerals for the multinational corporation Rio Tinto in Pilbara, Western Australia. / PHOTO_RIO TINTO

For the railway sector, the use of GNSS presents a number of challenges of both a technical and cross-cutting nature. Cross-cutting challenges include those related to protection, cyber-security, legislation and regulation, standardisation, and speed of implementation; while the technical challenges include issues such as dealing with interference, the multipath effect, the integrity of the satellite signal, the overcoming of communication ‘shadow areas’ such as tunnels and mountains, highly complex lines that incorporate forks and junctions, and more precise recognition of parallel lines and stations.

With regard to the future of GNSS in the railway sector, a number of short, medium and long-term milestones have been identified. The most immediate goal is to be able to locate trains with optimum precision, as this will make it possible to increase track capacity. Another milestone is the development of virtual balises based on the continuous transmission of PVT data, which will reduce costs. Forthcoming developments also include detection of movement of rolling stock while the on-board ETCS is disconnected (this is known as cold movement detection, or CMD).

Medium-term goals include the development of ERTMS Level 3, whose defining characteristic is moving-block signalling. This technology will greatly increase the current ability to manage line capacity.

Long-term milestones include driverless trains, although a number of initiatives in this area –such as the Rio Tinto Driverless Cargo Line in Australia– already exist. This driverless line, known as the ‘robot train’, incorporates 1,700 kilometres of track and 220 monitored locomotives. It records 12 GB of data traffic per day and uses automatic train detection logic based on ERTMS Level 2. Using this architecture, the multinational mining corporation Rio Tinto has developed predictive models that can detect potential failures in upcoming operations and recommend maintenance activities. As one would expect, final approval of these activities lies with the technical personnel.

In December 2017, this European project, financed by the GSA (European Global Navigation Satellite Systems Agency) as part of the H2020 Programme, began with a set duration of 24 months. The 14 European companies from five EU countries that participated in the ERSAT GGC project are RFI (project coordinator), Hitachi STS (formerly Ansaldo, technical coordinator), RINA, Trenitalia, Radiolabs, Italcertified and Bureau Veritas for Italy; Adif, CEDEX and Ineco for Spain; IFSTTAR and SNCF for France and UNIFE for Belgium.

The final objective is to contribute to the standardisation of the certification process for the adoption of satellite navigation systems (GNSS) in the European Rail Traffic Management System (ERTMS) standard. The scope of the project was very ambitious, working towards the consolidation of an improved ERTMS functional architecture that includes GNSS, safety studies, definition of a procedure for the classification of railway lines in relation to the ‘virtual balise’, development of a set of tools to assist in this classification, measurement campaigns in three countries (France, Spain and Italy), analysis of the data in the laboratories, evaluation of the architecture, procedure and tools by independent NoBos (Notified Bodies) and, finally, dissemination of the results and activities of the project in different national and international forums.

The ‘virtual balise’ concept has been under development for several years in previous projects launched by GSA, ESA and Shift2Rail, and consists of providing positioning information to the train by means of GNSS signals, instead of the physical balises required by ERTMS.

The ‘virtual balise’ concept has been under development for several years and consists of providing positioning information to the train by means of GNSS signals, instead of physical balises

For this purpose, the onboard equipment will consist of a new module called Virtual Balise Reader (VBR), which will process the GNSS signals and compare the GNSS coordinates with the list of coordinates onboard, reporting the corresponding virtual balise to the Eurocab when the coordinates stored for it are reached. This will make it possible to reduce the number of physical balises installed on the tracks, with the resulting savings for infrastructure managers, (Adif in the case of Spain) in terms of installation tasks, maintenance, theft, etc. This requires adequate reception of the GNSS signal at the points where the physical balises are to be installed, and therefore requires the classification of the railway lines according to the ‘quality’ of the GNSS signal received in each section.

The procedure will identify the sections/points where it is feasible to deploy a virtual balise so that the performance of the GNSS signal in terms of availability and accuracy meets the requirements.

The participation of Spanish companies in ERSAT GGC was distributed in such a way that CEDEX collaborated on the measurement campaign, integrating the tools in its laboratory and analysing the results of the different campaigns, contributing significantly to the customer’s last Demo. For its part, Adif purchased the necessary equipment for the campaign and provided a line and a laboratory train to carry out the measurements to be analysed at a later date.

Lastly, Ineco played a key role by participating in almost all of the work packages, contributing its knowledge in the areas of GNSS and ERTMS given its experience in previous projects such as GRAIL, GRAIL 2, NGTC and STARS. In particular, the company contributed to the consolidation of the functional architecture of ERTMS, the definition of several tools for the toolset, the participation in the Spanish measurement campaign, the analysis of the data from the Italian and Spanish campaigns, and lastly, contributing to the demonstration with the customer and the dissemination activities.

Measurement campaign in Spain

For the test campaign in Spain, Adif selected a line equipped with a Telephone Blocking (TB) system and with low traffic density. Specifically, line No 528 of the Conventional Network between Almorchón (Badajoz)-Mirabueno (Córdoba), which is of type E, with a total length of 130.1 kilometres and which is not electrified, although the runs were made on the section between the Almorchón and La Alhondiguilla stations, which is 94 kilometres long and has a maximum speed of 60 km/h.

Coordination between Adif, Ineco, CEDEX, IFSTTAR and DLR was key to the success of the hours and 20 runs were carried Spanish campaign. A static calibration test lasting 12 hours with 20 runs was carried out over 10 days of the campaign, at different times, in order to cover the various satellite positions of both the GPS and Galileo constellations. With all the data collected (GNSS signals, images and odometry), we moved on to an analysis phase, where the set of tools also developed in the project would make it possible to classify the line regards to the main local hazards to the GNSS signal on railway lines: interference, multipath, NLOS (Non-line-of-sight) and degraded performance.

All measurements were made on a Talgo laboratory train (BT-02), which was equipped with:

• GNSS Antenna: AntCom G8-PN
• GNSS Receiver: Javad Delta3
• GNSS Receiver: Septentrio AsteRx2e
• Splitter
• Laptops
• UPS
• Video camera
• Fisheye system

Main GNSS local feared events on railways. /
SOURCE_ERSAT GGC PROJECT

Tool development (Degraded performance indicator)

Ineco contributed to the development of different tools used to classify the areas of the train lines as green, yellow or red, for the placement of the virtual balise. In particular, two tools were developed to be integrated into the project:

1. SBAS_Health_Monitoring_tool (SHMT): assigns a health status to each GPS satellite by analysing the message received from EGNOS (European Geostationary Navigation Overlay Service).
2. GNSS4Rail: a simulation tool that makes it possible to manage a highly accurate 3D model of the railway line environment (both in rural and urban environments) based on a surface model and the ability to launch point or time simulations along the entire line with different GNSS constellations (GPS and/or Galileo) and for any time frame. The inclusion of the Galileo constellation was an added value to the project and enabled multiconstellation simulations (use of several GNSS constellations), following the path traced by safety market applications. Moreover, the prognosis capability provides a clear advantage over other applications that only analyse real, static data from the past.

The GNSS4RAIL tool provides the following advantages in the deployment phase:

• Support for feasibility analysis and planning of the deployment of virtual balises on the line.
• Preliminary identification of feasible sections for deployment.
• Analysis both along the railway line (spatial domain) and for a time interval (time domain).
• Minimises the data acquisition campaigns with an auscultation train mainly thanks to the temporal analysis.

Advantages in the operation phase:

• Support as a performance predictor of deployed virtual balises.
• Provides pre-tactical information to the management of GNSS-based railway operations.

The possible uses of the tool are not limited to the specific application of the virtual balise; it can also be used to determine in advance the ‘coverage’ of the GNSS signal at any point on a line and at any given time, and these results can be used for other applications such as operations planning, fleet control, passenger information, ticketing, maintenance, etc. It can also be applied in other sectors such as road transport, maritime operations in ports and VLL drones/aircraft air operations in U-Space.

When the Galileo satellite radio navigation and positioning system is fully operational, with its 30 satellites deployed, it will be possible to determine the location of people and objects with a precision and speed that are currently unattainable. In addition, it will provide Europe with a navigation system that is independent from the existing satellite positioning systems such as the North American GPS which operates using 31 satellites and Russia’s GLONASS, which uses 24 satellites.

The North American and Russian systems, along with the Chinese BDS, operate under military control, making Galileo the only one designed for civilian purposes and completely open to commercial use. It will also provide Europeans with independence from the Russian and American systems, which is of strategic importance, taking into account that, if they were to be blocked, up to 10% of the European economic activity depends to a greater or lesser extent on satellite navigation.

The importance of these systems in the world economy and transport is growing, along with the range of uses. It is for this reason that, after more than ten years of work, the European space industry and institutions have been able to conduct a project to deliver the highly competitive performance that will finally give Europe its desired technological and strategic independence. It will also allow access to a market with great potential for growth. See https://www.gsc-europa.eu/.

Galileo will provide signals for positioning, navigation and time measurement that are much more accurate than the other systems

When it is fully operational, Galileo, which was developed by the EU with the assistance of the European Space Agency (ESA) and whose services are operated by the European Global Satellite Agency (GSA), will provide signals for positioning, navigation and time measurement with much greater accuracy than the other systems, free of charge, for an unlimited number of users, and with the guarantee that the signals will be available anywhere in the world. It will be interoperable with the GPS system and will offer a paid commercial service that provides high precision and authentication.

Moreover, Galileo will offer a two other services: the PRS (Public Regulated Service) service which has highly robust signals that protect against malicious interference and which is intended for government use by security and civil protection organisations; and support for the SAR service (search and rescue), a European contribution to the international rescue service COSPAS-SARSAT. One of the biggest innovations is the incorporation of a return channel that informs those seeking assistance that their message has been received and that help is on the way. In addition, the Galileo technology makes it possible to reduce the search radius, and with it, the rescue time, which is a critical factor in saving lives on these missions.

According to the European Global Satellite Agency (GSA), the market for applications based on satellite navigation systems will grow 11% per year in Europe over the next few years, reaching 165 billion Euros in 2020, just for activities directly related to the system (chips, maps or services), without taking into account the activities facilitated by this technology, such as mobile phones with satellite navigation capabilities (GNSS). Galileo will be key to the introduction of this technology to the market, to complement the GPS system.

Galileo, in conjunction with GPS, will open a new era of satellite navigation through the introduction of the ‘multi-constellation’ concept. In the case of rail transport, aviation or road, this combined use will be very useful for fleet management, pinpointing the location of vehicles or vessels in real time, even in remote locations or in areas with poor visibility.

Satellite navigation is also an essential tool for scientists, astronomers, geologists and biologists who follow the movements of planets, the Earth and wildlife. For example, this type of positioning and location system allows animal tracking or drone monitoring. In addition, its time measurement, which is accurate to one billionth of a second, allows all kinds of measurements and scientific experiments to be performed with great accuracy.

1.5 BILLION FOR SATELLITE MANAGEMENT

In December 2016, the GSA, the organization responsible for operation of the Galileo system, awarded the contract for its operation and maintenance for the next 10 years to Spaceopal, a company formed by the Italian company Telespazio and the German company DLR GfR, which already managed the Galileo Control Centres (GCC) in Italy and Germany, respectively. Spaceopal’s industrial team includes the participation of a Spanish group led by Ineco with the collaboration of INTA and Isdefe.

The contract, valued at 1.5 billion Euros, includes the operation and maintenance of the Galileo system:

• Operation of the Galileo satellites from the two main control centres located in Germany and Italy.
• Service and information to the users, as well as activities for the evolution of services and applications from the GSC centre, located in Madrid, for the data distribution network of Galileo.
• Logistics and maintenance of the system.
• Management of minor developments and support for major developments of the system.

Named after the Genius

The astronomer, physicist and mathematician Galileo Galilei, born in Pisa (Italy) in 1564, would certainly appreciate the progress of a project like the one that bears his name. He was found guilty by the Inquisition for maintaining, among other theories, that the Sun was the centre of the solar system and the Earth rotated on its own axis. Although there is no historical record, he is credited with the famous sentence spoken before the court: Epur si muove. Although he officially recanted his scientific assertions, thanks to which his prison sentence was commuted to lifelong house arrest, he continued researching them until his death in 1642, the same year in which Isaac Newton was born. The image shows, Galileo teaching the Doge of Venice how to use a telescope. Fresco de Giuseppe Bertini (1825-1898).