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ERSAT EAV Report Summary

Project ID: 640747
Funded under: H2020-EU.2.1.6.

Periodic Reporting for period 1 - ERSAT EAV (ERTMS on SATELLITE – Enabling Application Validation)

Reporting period: 2015-02-01 to 2016-01-31

Summary of the context and overall objectives of the project

The Horizon 2020 funded ERSAT EAV project aims to verify the suitability of EGNSS services as EGNOS and Galileo for the railway sector – and in particular within the regional lines. The project is defining and developing the safe localisation of train positioning based on satellite technology and ensuring such a system is in harmony with the European ERTMS standard.
The main general objectives of ERSAT EAV are the following:
• To improve the sustainability and growth of the regional and local railway lines, guaranteeing the safety:
• minimizing the costs for railway signalling infrastructure, without sacrificing safety;
• safeguarding the European efforts for standardization of signalling systems (ERTMS);
• promoting the adoption of GNSS technology into the ERTMS for improving the competitiveness of European railway industry.
• The utilization of EGNOS and Galileo Services, as foreseen in the ERTMS MoU signed in 2012 by the railway stake-holders:
• Exploiting and adapting the enabling GNSS key technologies;
• Complementing the existing GNSS technology and operational services for railway application, fulfilling user requirements (i.e. SIL-4).

In order to reach such goals, the ERSAT EAV project activity is structured according to the following steps:
• starting from the definition of the railway requirements and scenarios, in particular:
• involving the Railway Stakeholders (Users and Industries) in requirement identification and harmonization;
• creating liaisons with other related projects (3INSAT, NGTC, S2R, GRAIL2, SATLOC …);
• verifying the suitability of EGNSS (including EGNOS and Galileo early services) for safety railway application, focusing in particular on the regional lines’ scenario;
• Conducting a measurement campaign, in real operating conditions, and analyzing the results, in order to evaluate the gaps to be filled, in terms of technological criticalities and in relation to the current railway requirements;
• Defining the system solution, in terms of system architecture and related specifications, for the safe localization of the trains, based on satellite technologies harmonized to the European ERTMS standard;
• Analyzing the impact in terms of cost/benefit and sustainability;
• Developing the solution in two phases:
• 1st Phase: Modelling and Simulation, in the DLR certified lab (RailSite) and using a DLR mobile lab for in field measurement & testing (RailDrive);
• 2nd Phase: by implementing the innovative SAT-based solution on the Trial Site made available by RFI & Trenitalia, and part of the Sardinian regional line (Cagliari-San Gavino).
• Testing and validating the solution that will become a reference to be considered in future standardization and certification initiatives;
• Disseminating and exploiting the ERSAT EAV results, involving railways and satellite communities, contributing to the standardization process of the ERTMS platform with GNSS.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

"All the project activities have been carried out according to the work program that has been revised at the end of 2015 (Gantt chart v.02) and agreed with GSA Project Officer as well as with the project reviewers. Basically this latest version of the project planning extended the time duration of almost all the work packages, while ensuring the final project deadlines, in order to allow time to collect, consolidate and harmonize all the project requirements and deriving from them all the inputs needed for the safety analysis, the system and sub-system architectures definition, the measurement campaign requirements, as well as and the cost/benefit analysis.

In the early stage of the project, all the requirements to be considered in ERSAT EAV have been identified and defined by the WP2 (ERSAT EAV REQUIREMENTS). In particular part of such requirements come directly from the users, the railway operators and their Association, some of them involved as project partners (i.e. ASSTRA, DB Netz, RFI and Trenitalia), and the remaining part deriving form a strategic liaisons with other relevant initiatives (past and the near future), concerning satellite technologies in the railway sector: i.e. 3INSAT, NGTC, S2R, GRAIL2, SATLOC ...
The user’s needs considered:
• The European market evolution that is setting new priorities on the ERTMS technology roadmap (see the ERTMS MoU signed in 2012 by the railway stake-holders, that envisaged both GNSS localization and IP TLC as new technologies to be introduced in the ERTMS standard);
• Some international markets, where the adoption of the new satellite assets is taking place at a much higher speed than in Europe: i.e. in Australia, USA and Russia
Bearing in mind that the scope is the definition of a standard solution that can be customized on each country, WP2 addressed the following issues:
• Definition of requirements apportionment strategy,
• subdividing the requirements in: safety and interoperability standard, localization and augmentation system, TLC system, ERTMS/ETCS signalling system, operational rules;
• Identification of reference scenarios and related specific requirements, selecting in particular German and Italian regional railway lines, including among them the Sardinia Trial Site line.
• Harmonization of user requirements, according to the above apportionment strategy, and proposal of a standard solution for the satellite-based technology signalling system;
On the basis of these harmonized requirements, the WP3 performed a GNSS Measurement Campaign in a real railway scenario, namely the Sardinia Trial Site:
• Collecting raw data from COTS GNSS receivers both on the equipped running train as on the wayside locations where the Reference Stations of the Ansaldo STS proprietary Augmentation network, have been placed;
• Constructing the ground truth as reference for the measurements
• Post-processing the collected data.
• Identifying the GNSS signal blocking sources and their effect on ERTMS
All such data have been collected and stored in an ad-hoc built database containing all the real recorded signals from GPS, Galileo, GLONASS and EGNOS satellites in order:
• To assess the current achievable performance in real scenarios
• To compare candidate GNSS configurations and algorithms
• To create GNSS performance baseline scenarios.
Additionally, a complementary measuring data campaign has allowed analysing GNSS blocking sources and EMI on the ERSAT pilot line. Likewise, this data campaign has supported the main GNSS measuring campaign with preliminary results with EGNOS performance.

In parallel to the WP3 activities, the WP4 (REFERENCE ARCHITECTURE DESIGN & PERMORMANCE ANALYSIS) performed a preliminary Safety and Hazard Analysis, aimed to identify hazards related to GNSS LDS ensured essentially by both EGNOS and a Local Augmentation Network. This analysis got started by a joint working group activity that involved both the nominal participants in the task 4.1, as well as Ansaldo STS that spent unplanned extra effort, as additional contributor making available its expertise in Railway Signalling domain as well as in the Safety related aspects. The possible hazards has been preliminarily assessed, in term of risks and highlighting necessary actions to mitigate these risks to an acceptable level. As the application of GNSS, and in particular EGNSS, in Railway Signalling is completely innovative, the process of adaptation, from the aviation environment to the railway one is very complex and it must also be based on the specific requirements and specific characteristic belonging to ERTMS domain, identifying all the specific hazards and their possible mitigations. For this reason, this safety study has to be considered preliminary, further harmonization activities are required and planned in the second part of the project to contextualize the hazards and the performance of a GNSS receiver in the railways environments and in the on board ERTMS constituents.

In the meantime, WP4 designed a 2-tiers Reference Architecture, as well as its subsystems (OBU LDS, TAAN, TALS, EGNOS and CPS) and their internal interfaces. The first tier essentially consists of EGNOS, possibly extended by incorporating multi-constellation capabilities, as well as specific data supporting railway applications. The second tier, consisting of a Track Area Augmentation Network (TAAN) making use of additional wayside Ranging and Integrity Monitoring Stations, adds evolved functionalities to the EGNOS, in terms of additional augmentation real time data for high accurate localization, together with all the auxiliary information required to compute train location, speed and SIL-4 confidence intervals. TAAN Architecture has been designed, including the extension of the existing Sogei's GRDNet Network Control Centre in order to implement the 2-tiers Integrity Monitoring Algorithm, as well as interfaces versus the TALS (Track Area LDS Server). The 2-tiers Integrity Monitoring Algorithm has been studied and a preliminary implementation and post-processing test carried out with existing Reference Stations raw data. Five TAAN Reference Stations receivers and relevant accessories have been acquired. Candidate Sardinia Sites for hosting the TAAN Reference Stations have been surveyed and selected. GNSS Antennas Monumentation Designed has been developed, taking into account single sites logistic constraints. Agreement with relevant ownerships signed. High Quality of Service Communication lines between Single Reference Stations and the GRDNet Control Centre have been booked with the Public Network Operator.
GNSS-LDS sub-system architecture has been defined with the relevant functionalities. The GNSS-LDS receives data from GNSS SIS, by means of the TALS, from Track Data Base Repository and from ERSAT –CPS and performs a PVT estimation and the associated confidence interval. In addition, the interfaces between this sub-system and the other ones in the reference architecture have been detailed.

In the same way, the requirements and the related architecture of the ERSAT CPS have been defined, as well as CPS sub-systems and two different algorithms for known blocked scenarios. Moreover, a trigger of GNSS denied areas identification, as well as the standalone operation initialization, have been defined.

The defined reference architecture has been tested and validated by means of a GNSS based LDS simulator, that exploits and extends the existing GNSS 3InSim Simulator, provided by RadioLabs. This is a high fidelity simulator of the data processing chain related to both tiers (1+2) ranging and integrity monitoring sub-systems and the GNSS OBU LDS with ERSAT CPS sub-system.

The system performances have been analysed in terms of KPIs, based on simulations with:
• Real data acquired during the measurement campaign (from WP3);
• Synthetic data created on the basis of the reference scenarios defined in WP2.

Concerning the evaluation of the impact generated by the introduction of GNSS in Railway and in particular its signalling application in regional and local railway lines scenarios, WP5 (IMPACT & SUSTAINABILITY ANALYSIS) analysed both the economic effects as well as its wider impact for the community, in terms of safety and environmental sustainability.
WP5 produced a methodological evaluation set up for the project, covering all the different dimensions and fields (economics, technical effectiveness, environment, social issues) for validation. This set up ensured a neutral, objective and proper measurement of the results of the project.
The specific objectives reached by WP5 have been:
• The consolidation of a methodological framework to analyse the overall impact of the implementation of this type of technology;
• The collection of all the relevant input data, in terms of costs and other parameters related to the operation of the GNSS solutions;
• The impact analysis in the relevant geographical scopes;
• The conclusions in terms of the most relevant impacts for the community and for each player involved.

In parallel Telespazio started some analysis for the implementation of simulations considering the Galileo and multi-constellation scenario, activity related to the WP 6.
Some constraints and requirements (requirements on train kinematics, Galileo constellation configuration, receiver model etc.) have been preliminary analysed to drive the activities of the Task 6.4.
Concerning the dissemination activities of ERSAT EAV project, several initiatives have been carried out within the WP 12, especially in both workshops organization and participation. Among the most important it is worth mentioning:
• The Presentation of ERSAT EAV project in the ION GNSS+ 2015 Congress, in September 14-18, 2015, Tampa, Florida;
• The Presentation of ERSAT EAV project within the EGNOS Service Provision Workshop that has been held in Copenhagen, on 28th-30th September 2015;
• Presentation of ERSAT EAV project in occasion of the visit of the delegation of European Parliament Industry, Research and Energy (ITRE) Committee to the European GNSS Agency, in GSA premises in Prague;
• Presentation of ERSAT EAV project, as developments supporting railway regional lines, in occasion of an "Exchange between DB Netz and SNCF" in Paris, with the aim to contribute to each other's Signalling innovation activities;
• A special session on ERSAT EAV activities at the International Workshop on "GNSS technologies" organised by SOGEI in Rome. This occasion was preceded by the presentation of the TAAN development and the 2-ties Augmentation Architecture to the RTCM Organization, in charge of defining High Precision messages Exchange formats and communication protocol. A new Working Group, named "Integrity Monitoring for High Precision Applications" has been created at the aim at defining new messages to be used by High Accuracy and High Integrity applications such as Rail. Preliminary Results of the Working Group have been Presented to the RTCM Plenary Session in January 2016. The third edition of the Workshop IGAW 2016 (International GNSS Advances Workshop), dealing with state of the Art and advances on GNSS, has been organized and held by SOGEI in Rome. A total day was devoted to Rail applications, with the participation of GSA, ESA and ERA representatives. Relevant Professors from International recognized Universities (e.g. Stanford University) attended to this meeting, showing their experience in the application of High Integrity GNSS for the Rail Sector;
• A workshop on ERSAT EAV project hosted by RFI in Rome that has been attended by high representatives from the GSA (the Executive Director, Carlo des Dorides), ERA (Josef Doppelbauer, executive director), RFI (Maurizio Gentile, CEO), ANSF (Amedeo Gargiulo, executive director) and Ansaldo STS (Stefano Siragusa, CEO), among others. The representatives of the entire Rail/GNSS value chain were present at the meeting confirming that European railways are standing at the edge of a technological breakthrough where GNSS will work in tandem with current technologies, resulting in a safer and more reliable railway signalling.
Finally ERSAT EAV project is submitting papers and articles in order to disseminate part of its results, like the following:
• a paper related to ERSAT EAV project to TRA2016 - 6th Transport Research Arena Conference, April 18-21, 2016, Warsaw, Poland;
• a paper titled “High Integrity Two-tiers Augmentation Systems for Train Control Systems“, Neri, A., Capua, R., Salvatori, P., ION Pacific PNT 2015, Honolulu, April 20-23 2015."

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Remarkable progresses are distributed throughout the entire project life cycle. Since the requirements, drawing on different markets and national peculiarity, as well as different scenarios, that achieved a high level of synthesis and harmonization not common at the time with other similar projects. This was possible thanks to the presence of many railway infrastructure managers, operators and their Association, like ASSTRA, DB Netz, RFI and Trenitalia.
On this basis, another relevant outcome is represented by the GNSS measuring campaign, that collected data from the available GNSS constellations and EGNOS operational satellites, assessing the achievable level of performance of the GNSS service in the real railway environment, namely in the Sardinia trial site. The completeness of these data, required for this evaluation, came out from the measurement configuration, adopting not only static but also dynamic tests that have been performed on board to an operational train along a Regional railway line. In addition to raw GNSS data collection in RINEX format, also GNSS samples have been recorded at IF level, as well as the interference monitoring and GNSS signal characterization have been performed.
Since the application of GNSS, and in particular EGNSS, in Railway Signalling is very innovative, the knowledge transfer and adaptation processes, from the aviation environment to the railway one are very complex. For this reason, ERSAT EAV got started by jointly involving not only ESSP experts in EGNSS, and their safety and certification branches but also ASTS, as expert from the Railway Signalling domain and its Safety related aspects. The goal was taking into account from the early stages of the project both: the specific requirements and characteristic belonging to ERTMS domain, as well as identifying and considering all the specific hazards and their possible mitigations. Following this approach, ERSAT EAV completed a first preliminary safety analysis while further harmonization activities are already planned to contextualize the hazards and the performances of a GNSS receiver in the railways environments and together with the on board ERTMS constituents.
Concerning the ERSAT EAV solution, it is worth to mention that the adopted strategy in system design, consisting in the best approach for minimizing the impact on the ERTMS ecosystem, maintains full compatibility with the current legacy ERTMS Level 2 solutions.
In the present situation, the train location determination in ERTMS/ETCS level 2 is mainly based on physical balises that are a kind of transponder installed on the track at geo-referenced locations. When the train passes on a physical balise, its on-board Balise Transmission Module (BTM) is able to detect this event, extracting the specific message (telegram) contained in that physical balise. At this point, the BTM applies a time and odometer stamp to the received message- that contains among others a unique balise identifier and delivers it to the Radio Block Center (RBC) via a train-to-track mobile network (e.g. GSM-R), using means of a safety protocol. Then the RBC processes the reported information and sends back to the train the so-called Movement Authority (MA) containing the permission for the train to move to a specific location with speed supervision.
Therefore, in present ERTMS L2, the train position and speed are computed on board by the odometer, which relies on the balises deployed along the track, as reference points, to periodically reset the accumulated errors. In particular, the balises determine the train absolute position and the odometer estimates the relative distance from the Last Relevant Balise Group (LRBG).
To speed up the integration of GNSS technology into ERTMS/ETCS, minimizing its impact, the concept of “Virtual” Balise has been introduced in ERSAT EAV. In essence, the GNSS based Virtual Balise Reader estimates the instant at which the train will pass over the location where the next Virtual Balise is located. At that moment, the Virtual Balise Reader generates the same signals that would have been produced by the BTM when detecting a physical Balise, by sharing the same logical and physical interface, then emulating the BTM behaviour. According to this system approach, the On Board ERTMS/ETCS location determination functions do not need to be changed for the purpose of ERSAT EAV.
A major ERSAT EAV challenge in the adoption of GNSS-based LDS is to guarantee at system level the same Tolerable Hazard Rate (THR) with the mechanical odometry which has to be less than 10-9 during 1 hour of operation to comply with the CENELEC Safety Integrity Level 4 (SIL-4) requirements.
To meet the needs of railway applications without the use of wayside train detection subsystem, wide area augmentation systems of the next decades should therefore exploit multi-constellation capabilities and improved ranging and integrity monitoring algorithms.
Local Area Augmentation Networks currently working for other purposes (e.g. land surveying and cadastral application) may provide such augmentation services in the short term, and constitute a densification of wider regional networks allowing the exploitation of future High Accuracy and Integrity Commercial Services. Furthermore, currently available commercial augmentation networks, although serving large areas of the World, do not guarantee any Safety Integrity Level.

The overall integrity of ERTMS will result from the integration of the evolved SBAS and Local Augmentation networks. In particular, the ERSAT EAV project is focusing on the achievable performance, in terms of integrity monitoring and LDS accuracy of 2-tier architectures consisting of a ranging and integrity monitoring network that provides the augmentation data, to the train on board units (OBU) equipped with a satellite receiver. Moreover, additional sensors which provide increasing positioning availability of the system are also analysed.
The first tier consisting essentially of the evolved EGNOS system complemented with the EGNOS-GALILEO Application for Railway. It will provide: a) GEO Ranging; b) Wide Area Differential (WAD) corrections; c) GNSS/Ground Integrity Channel (GIC). All these carrying the information concerning the health of the monitored satellite constellations, as well as all the data concerned with the GNSS SIS status required for the computation of confidence intervals by the OBUs. The Wide Area Differential Correction, valid for the monitored constellations, are then used by the OBUs to increase the LDS accuracy, while mitigating hazards related to satellite navigation data and atmospheric propagation anomalies.
The 2nd tier, denoted in the following as Track Areas Augmentation Network (TAAN), will consist of a set of RIM Stations distributed along the railway line, a TAAN Control Centre (TAAN-CC), and a Communication Network interconnecting the TAAN-CC with the RIM Stations. The TAAN will provide TALS with: a)Observation Data; b)Navigation Data; c)Healthy satellite list; d)Probability of satellite and constellation fault.
By its part, TALS is in charge of computing local differential correction messages for all satellites tracked as “healthy”, supporting, among others, high performance navigation modes, and a Local Augmentation Channel providing all the data required by the On Board Units (OBUs) for determining the subset of visible satellites to be used for PVT computation, meeting both the accuracy and integrity requirements, for all supported operational modes, and for the computation of the confidence intervals and position and velocity integrity.

From the economical point of view, ERSAT EAV performed an impact analysis at both national and European levels, showing that the introduction of the GNSS-based ERTMS with telecommunications based on public GSM + SatCom proves to be convenient for the economic system. In particular, it generates relevant savings in operating expenses (-67% each year compared to the traditional ERTMS with GSM-R).
It is particularly beneficial for infrastructure managers in that it greatly reduces the need to invest and operate Eurobalises and the GSM-R.
For railway undertakings the convenience of the ERSAT scenario derives from the consideration of collateral benefits connected to the time and energy saved because of the optimisation of train operations (in particular at the start of missions, when the GNSS technology allows to locate the train immediately thus avoiding Staff Responsible Mode), and it can be further improved if the savings of Infrastructure Managers (IM) are partly transferred to train operators via the infrastructure charges.

Therefore, the ERSAT scenario can remarkably contribute to the dissemination of ERTMS and to the relevant impacts that it entails.
For example, in low density lines not equipped with Automatic Train Protection (ATP), GNSS-based ERTMS can improve safety at a lower cost.
Furthermore, ERTMS will allow the implementation of “economic driving”: concepts which can generate benefits up to 70 million euro per year though savings in energy consumption and braking equipment.

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