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Global Navigation Satellite System (GNSS) integrity is defined as a measure of trust that can be placed in the correctness of the information supplied by the total system. Initially developed for safety critical applications in the aeronautic domain, this concept has attracted more and more attention from terrestrial GNSS-based applications in recent years. The main problem of integrity monitoring for urban transport applications is related to GNSS signal degradation due to local effects such as multipath and non-line-of-sight reception. This article proposes two integrity monitoring schemes with two classes of approaches, based on either the snapshot weighted least-squares residual or sequential weighted extended Kalman filter innovation. The integrity monitoring schemes are mainly realized by two modules: accuracy enhancement, in which measurement errors are better characterized, and integrity monitoring, in which one of the fault detection and exclusion techniques, i.e., the Danish reweighting method, is applied. The results with real GPS data collected in urban canyons show that the proposed system can effectively improve positioning accuracy and guarantee system integrity.

ION ITM 2022 - International Technical Meeting of Institute of Navigation, Long Beach, CA, ETATS-UNIS, 25-/01/2022 - 27/01/2022; Localization function for an advanced intelligent transport system, such as an autonomous vehicle, must ensure various operational requirements such as safety, accuracy, availability and continuity of service, anytime, anywhere, at a reasonable cost. Global Navigation Satellite System (GNSS) have many advantages insofar as they present the most accessible technology to the user to determine its position with a certain accuracy without prior knowledge. However, in an environment where signal reception may not be optimal especially due to phenomena such as satellite blockage, multipath, intentional or unintentional interferences and spoofing, it becomes very challenging to meet all these requirements, especially those related to operational safety. The latter is measured by evaluating the integrity of the localization function. It can be evaluated through a Protection Level, which is calculated by the receiver to self-monitor its integrity, also called RAIM (Receiver Autonomous Integrity Monitoring). In the literature, integrity in presence of multipath and NLOS has been extensively investigated [1] as well interference detection and mitigation solutions [2]. However, the impact of interference presence and mitigation on integrity monitoring is not deeply addressed yet. In this study, we evaluate some key performance indicators (KPI's) for GNSS users. These indicators will be evaluated for three different cases; 1) when no interference is applied and clean GNSS signals are processed. 2) In the presence of interference but without any mitigation technique. 3) After applying a mitigation technique at the pre-correlation level to filter the interference signal. The mitigation technique relies on state-of-the-art Notch filters provided by a Septentrio receiver. The interference signals are generated in the laboratory to produce disturbances in the GNSS band. Thus, and thanks to the a priori knowledge of the true position, it is possible to establish the Stanford diagrams for these cases. A deep analysis of performance in the presence and absence of interferences and in the presence and absence of a mitigation technique allows the first conclusions to be drawn on the evolution of accuracy, availability and operational safety indicators. The preliminary results reveal the importance of considering, from the design phase of the localization function, the possibility of dealing with this phenomenon, in particular in the measurement weighting model to use for enhanced performance.

GNSS are widely used in localization applications. These systems have the advantage of being able to locate, at low-cost, receivers anywhere on the planet's surface without prior knowledge of the position. However, the accuracy of the provided position strongly depends on the quality of reception and on the number of signals received. And these depend on the environment around the receiver. Indeed, certain environments such as urban canyons or forests are known to be challenging because multiple phenomena such as multipath, Non-Light Of Sight (NLOS), or interference are common there. These phenomena induce an erroneous estimate of the position. In applications where the localization function does not constitute a critical function involving the safety of the overall system, this erroneous estimate only constitutes an inconvenience. But in applications for which the safety of goods or people is at stake, the tolerance of what is called the integrity risk is infinitesimal, not to say null. Moreover, in this type of application, it is not so much the position that matters but the ability to limit the unknown position error. For that, the literature proposes different possibilities of protection level calculation. The ideal protection level would be the one that limits the unknown error as closely as possible without ever underestimating it. This makes it possible to minimize hazardous operations as well as unavailability of the localization function. In this paper, we are interested in the impact of GNSS observation weighting models on the protection levels. We propose a model capable of carrying a multi-criteria and multi-parametric strategy allowing a better adaptivity to the navigation context. The encouraging experimental results show that a parametric and constrained modelling strategy of errors, from the design step, relaxes the requirements on the calculation of the protection levels. They also show the complementarity between the characterization of errors which must be concerned with the functional behaviour and a Fault Detection and Exclusion layer which is responsible for the dysfunctional behaviour.

ION ITM 2021 - International Technical Meeting of Institute of Navigation, Virtual, , 25-/01/2021 - 28/01/2021; The accuracy of the satellite-based positioning system is severely affected in the presence of local phenomenons like multipath, NLOS and interferences. These local effects are difficult to model due to spatial and (or) temporal dependencies. This study aims to model the position error on the track and later use it for the track classification. The characterization of the track errors can be beneficial as it can help to increase the capacity of the railway track by providing adaptable protection level and also for sending warning alerts to the other trains if any of them is in degraded mode to avoid any sort of accidents. We present a very simple machine learning approach to model the position error. For this purpose, we investigate the Expectation-Maximization (EM) algorithm to estimate the parameters of the Gaussian Mixture Model (GMM). We intuitively selected 3 classes to represent different error shape features to avoid complexity and to keep some diversity. In the learning phase, 5 different runs are used to capture as much as the error variations on the track throughout the day. The models estimated in the learning process is applied to the test samples for the track characterization. The results show that class representation varies due to the error variation within the day. For some particular obstacles, the track is always represented by the class that shows deteriorated conditions. It also shows that the class representation is very similar to the learning samples when the error models are applied to the test sample collected on a different day with a nearly similar satellite configuration.

L'article présente le projet ERSAT GGC et les techniques de détection des effets locaux sur les GNSS développées pour l'introduction du GNSS dans le système ERTMS/ETCS

Lambda Mu 22, 22e Congrès de maîtrise des risques et de sûreté de fonctionnement. Les risques au coeur des transitions (e-congrès), Virtuel, FRANCE, 24-/11/2020 - 24/11/2020; A modular and parametric approach to evaluate the safety of GNSS-basedsystems in railway signallingis presented in this paper.The complex system is broken down into modules that areformally modelled. This work is part ofa generic safety method.; Ce papier présente une approche modulaire et paramétrique pour évaluer la sécurité des systèmes avec GNSS dans la signalisation ferroviaire. Le système complexe est décomposé en modules puis modélisé de façon formelle. Ce travail s'inscrit dans le cadre d'une méthode de sécurité générique.

ENC 2020, 28th European Navigation Conference, Dresden , ALLEMAGNE, 23-/11/2020 - 24/11/2020; The work shows the high level concept and methodology followed for designing a geo-distributed simulation and verification infrastructure connecting remotely GNSS excellence centres and ERTMS/ETCS laboratories to evaluate the GNSS performances in the railway environment. Proper methodology and tools are adopted to simulate GNSS behaviour in different railway scenarios in nominal or in presence of global and local hazards. Particularly, the test-bed main goals are: i) achieving a realistic characterization of the environment in terms of railway and GNSS infrastructures able to evaluate the performances and properties of some fail-safe train positioning components in nominal and fault conditions; ii) defining a common test process framework for zero on-site testing instead of testing on-site saving effort and time. The test-bed offers the unique advantage to stress the global system in presence of very rare GNSS fault events instead of performing long and expensive measurement campaigns on field for detecting them and analysing their impact on ETCS. The work will show its description and the methodology adopted for its design and implementation.

ENC 2020, 28th European Navigation Conference, Dresden , ALLEMAGNE, 22-/11/2020 - 25/11/2020; GNSS observations weighting models have received attention in the past decades. Several reasons can explain this gain in consideration. It mainly corresponds to the emergence of autonomous, global, continuous, precise and integrity-compliant localization systems. Indeed, for safety critical applications, adopting a naive strategy of observations' equal weighting could not guarantee to achieve all goals, and even more for terrestrial applications where the local environment can strongly disturb signals reception. The existing observation models use one or two metrics to estimate the confidence to be given to an observation. The first is the satellites' elevations. This model considers that the satellites with low elevation are more subject to global errors (orbit and atmosphere errors) or local multipaths or NLOS phenomena. The second criterion is the carrier to noise ratio provided by the receiver. However, combining these two criteria by a simple multiplication of the two models taken separately, presents a limit: the result is no more « under control ». In this study, we propose to formulate a new weighting strategy using these two criteria more guided by expertise's expected results.

ENC 2020, 28th European Navigation Conference, Dresden , ALLEMAGNE, 22-/11/2020 - 25/11/2020; For land transport environment and railways in particular, the main limits of GNSS signal exploitations for an accurate and safe positioning comes from the local environment surrounding the vehicle. Obstacles induce multipath and non-line of sight signal reception that need to be detected for railway line characterization or feared event mitigation. In this paper, we show that the use of two techniques based on CN0 and camera respectively, can help to detect and label faulty events along a trajectory. The methods have been applied on a test run performed during the ERSAT GGC project in Spain. This paper presents first the techniques, then an analysis of the detections for evaluation.

The growing development of smart objects offers new opportunities for locating the connected traveler. However, tracking the pedestrian's trajectory remains problematic and navigation applications do not propose to track the traveller's trajectory on a multimodal scale autonomously. This work focuses on the implementation of a single solution capable of locating the user according to different travel modes and whatever the environment, using inertial,magnetic and GNSS sensors. In a first step, a new method for locating the cyclist is implemented. GNSS phase measurements are used to correct the velocity vector by time differences and themovement direction is constrained using inertial signals. These elements were used in a second time and adapted to implement a new method of pedestrian localization with a handheld sensor. The PDR approach which is an inertial navigation technique using dead reckoning is parameterized in an extended Kalman filter. An innovative update merging the device attitude estimation and a statistical estimation of the walking direction allows to correct the walking direction prediction and to obtain a consistent and smoothed estimate. GNSS measurements are used to correct the velocity vector, orientation, step length and absolute position. Finally, a multimodal approach is proposed and the management of transitions between the different algorithms, assisted by the use of an innovative sensor, is studied. Multimodal experiments in real conditions are conducted to analyze the performance of the proposed solution., Le développement croissant d'objets intelligents offre de nouvelles opportunités de localisation du voyageur connecté. Cependant, le suivi de la trajectoire du piéton reste problématique et les applications de navigation ne proposent pas de suivre la trajectoire du voyageur à l'échelle multimodale de façon autonome. Ce travail s'intéresse à la mise en place d'une solution unique capable de localiser l'utilisateur selon différents modes de déplacement et quel que soit l'environnement, à partir de capteurs inertiels, magnétiques et GNSS. Dans un premier temps, une nouvelle méthode de localisation du cycliste est mise en place. Les mesures de phases GNSS sont utilisées pour corriger le vecteur vitesse par différences temporelles et la direction de déplacement est contrainte à l'aide des signaux inertiels. Ces éléments ont été utilisés dans un second temps et adaptés pour mettre en place une nouvelle méthode de localisation du piéton avec un capteur en main. L'approche PDR qui est une technique de navigation inertielle à l'estime est paramétrée dans un filtre de Kalman étendu. Une mise à jour innovante fusionnant l'estimation de l'attitude du boîtier et une estimation statistique de la direction de marche permet de corriger l'estimation du cap de marche et d'obtenir une estimation cohérente et lissée. Les mesures GNSS sont utilisées pour corriger le vecteur vitesse, l'orientation, la longueur de pas et la position absolue. Enfin, une approche multimodale est proposée et la gestion des transitions entre les différents algorithmes, assistée par l'utilisation d'un capteur innovant, est étudiée. Des validations expérimentales multimodales en conditions réelles sont conduites pour analyser les performances d'estimation de la solution proposée.

2020 IEEE Intelligent Vehicles Symposium, LAS VEGAS, ETATS-UNIS, 20-/10/2020 - 23/10/2020; Over the last decade, the number of accidents involving Vulnerable Road Users (VRU), i.e. pedestrians, cyclists and motorbike drivers, has not decreased in the same way as accidents between passenger cars have. Cooperative systems based on Vehicle-to-X (V2X) communication make it possible to directly exchange information between VRUs and vehicles and to increase the overall situational awareness beyond the capabilities of on-board ranging sensors. To detect and avoid collisions, vehicles require up-to-date and precise information on the location and trajectory of VRUs. In this paper, we propose a VRU localization system based on Global Navigation Satellite System (GNSS), inertial sensors and ultra-wideband (UWB) round-trip-delay ranging technology. We present an exhaustive measurement campaign comprising pedestrians, cyclists and vehicles performed in an urban setting and show first results on the localization performance for a pedestrian crossing an intersection. In the experiments, the pedestrian inertial system supported by GNSS and UWB ranges is able to achieve 0.65m 1\sigma-position accuracy.

Groupede Travail GNSS et Positionnementde la CNIG, Bouguenais, FRANCE, 16-/10/2020 - 16/10/2020; Groupe de Travail GNSS & Positionnement du CNIG (conseil national de l'information géographique).

ION ITM 2020, International Technical Meeting of Institute of Navigation, San Diego, ETATS-UNIS, 21-/01/2020 - 24/01/2020; GNSS used as a standalone positioning system fulfils most of the requirements for many applications since decades. However, the need of high available, accurate and fail-safe positioning systems for new applications such as rail autonomous vehicles for train signaling applications motivates the community to explore novel solutions. In this context, multi-constellation multi-frequency GNSS receivers have the potential to enhance the positioning solutions. However, when applied to safety-critical land transportation system, the localization function not only needs to meet accuracy requirements, but more importantly, it also needs to bound the positioning errors in order to reduce the risk of unexpected and undetected faults. Thus, in order to reach continuous and fail-safe positioning solutions, the use of complementary heterogeneous sensors with a smart hybridization becomes essential. For safety-related and regulated applications as in railways, one will also need, as a next step, to develop the capacity of assessing the safety of the hybrid solution. The concept of integrity can help to reach this requirement and is currently investigated for rail applications. RAIM (Receiver Autonomous Integrity Monitoring) was first defined for aviation applications and is widely used for their safety assessment. However, due to the different safety requirements and operational environment in aviation and land applications (i.e. railway and road application), dedicated algorithms need to be developed for such applications. Indeed, terrestrial applications can face particularly harsh environments (urban canyon, forests ...) in which a dilemma appears between the (reduced) availability of visible satellites and the possibility of encountering multiple simultaneous errors (NLOS, multipath interferences ...). Under these conditions, implementing a strategy based solely on a FDE layer can lead to a decrease in the availability of the localization function. Conversely, relying solely on a strategy of weighting observation error models cannot constitute an acceptable solution from a safety point of view. Only a harmonious combination of these two strategies in a stringent environmental condition can achieve the availability and security requirements. With a real dataset collected along a railway line, we compare the positioning accuracy of a GNSS/IMU tightly coupled system before and after weighting and FDE schemes. The results show that the average value of Horizontal Position Error (HPE) has been reduced after applying the performance improvement method on the GNSS/IMU system. It also shows that the implemented Horizontal Protection Level (HPL) correctly bounds HPE.

The ERSAT-Galileo Game Changer research project, which concluded last November, has laid the foundations for GNSS satellite location technology to support train positioning on secondary railways, potentially reducing the cost of ERTMS deployment.This paper summarizes the main contributions of the project and the perspectives.

This paper provides a multiple sensor dataset collected by the CyborgLOC team during the intermediate competition of the Challenge MALIN (MAitrise de la localisation INdoor), which is a competition for indoor/outdoor real-time positioning. The sensors, including a GNSS receiver Ublox NEO-M8N, a Realsense D435i stereo camera, three Xsens MTi-300 and one PERSY (PEdestrian Reference SYstem), are mounted on different parts of the subject's body. The PERSY is a foot-mounted positioning device with a tri-axial accelerometer, a tri-axial gyroscope, a tri-axial magnetometer as well as a GNSS receiver Ublox M8T. The two scenarios are designed in a training centre of firefighters CFIS (Fire and Rescue Training Centre) in Blois, France to simulate the situation of firefighters during interventions. With total distances around 2 km for each scenario, the travelled trajectories passed through challenging environments including indoor, outdoor, urban canyon. The indoor part contains different stair levels, from the underground up to the 6th floor. The travel modes are vehicles and pedestrians. Several classical activities of firefighters are realized such as walking, running, stair-climbing, side-walking, crawling, passing above/below obstacles, carrying a stretcher, ladder climbing, etc. High accurate ground truth of stationary points and enclosing volumes are provided by the organizers of the competition, i.e., the Directorate General of Armaments (DGA: Direction Generale de l'Armement). Provided with raw data, they allow the evaluation of the positioning performances. This dataset is available on the data repository https://doi.org/10.5281/zenodo.4290789 .

47ème Congrès ATEC ITS France, PARIS, FRANCE, 22-/01/2020 - 23/01/2020; Le domaine de la géolocalisation s'est doté d'une méthodologie de référence indispensable pour évaluer et caractériser des terminaux GNSS destinés à la navigation terrestre. La série de normes EN16803 a pour objectif d'éclairer les choix des utilisateurs et de simplifier l'intégration des technologies satellitaires aux systèmes embarqués. Elle s'appuie sur une technique de métrologie instrumentale, identifiée sous le terme « Record & Replay » et offrant plusieurs avantages-clefs : - Restituer des environnements d'essais « Reproductibles » et « Représentatifs » du monde réel ; - Dissocier les erreurs de « Justesse » et de « Fidélité » pour enrichir les analyses ; - Etablir des scénarios de référence fiables pour « comparer les résultats de mesures ».

L'utilisation des GNSS (Global Navigation Satellite System) dans le milieu ferroviaire est d'ores et déjà une réalité sur le terrain. Mais les défis pour l'intégration des technologies de positionnement par satellites dans des systèmes complexes de contrôle-commande et de gestion du trafic ferroviaire restent nombreux.

This deliverable is the second report delivered by GATE4Rail WP3. The general objective of WP3 was to define a comprehensive methodology and the associated tools able to characterise the Global Navigation Satellite System (GNSS) performance into the railways application scenarios defined in WP2 in the framework of a VB detection in ERTMS (European Railway Traffic Management System)/ETCS (European Train Control System) context.The work performed in WP3 is focused on the definition of the main railway environments that will impact GNSS reception, thus PVT performance. This deliverable D3.2 in particular, defines which are the key hazards (both local and global) that have to be taken into account and simulated in order to cover the main events that can occur during a railway operational scenario and how error models will be introduced in the simulation framework defined by the project.

UCP, 3rd edition of the User Consultation Platform, Virtuel, , 01-/12/2020 - 02/12/2020; Comité européen de normalisation des normes GNSS pour la route et le véhicule autonome. Avantages de l'utilisation de la norme EN16803 pour le secteur automobile. Présentation.

WCRR 2019, 12th World Congress on Railway Research, Tokyo, JAPON, 28-/10/2019 - 01/11/2019; The use of GNSS positioning into the ERTMS/ETCS has been identified as the technology for supporting the detection of Virtual Balises (VB). However, the presence of local GNSS threats (e.g. multipath, non-line-of-sight (NLOS) or interference) that may not be detectable by a local or wide area augmentation network, can potentially lead to unbounded errors in the pseudorange measurement and ultimately to an error in the VB position that cannot be bounded with the required integrity. In order to prevent a priori the risk of this hazardous situation, VB must be located in areas there are no local threats that may lead a Virtual Balise Reader (VBR) on board the train to dynamically estimate unbounded virtual balise position errors. The ERSAT-GGC project has been funded to tackle with this challenge. This paper aims to present the techniques and methods developed to characterize track areas to know a priori which track portions are suitable for placing VBs. They will rely on basic equipment that every stakeholder shall be able to install and use, composed of a COTS GNSS receiver providing raw data and, when necessary, a spectrum analyzer. The paper describes and illustrates the selected techniques.

2019 International Conference on Indoor Positioning and Indoor Navigation (IPIN), PISE, ITALIE, 30-/09/2019 - 03/10/2019; With the highly development of navigation techniques during the past decades, the demand for seamless indoor-outdoor navigation is growing from different application fields especially for the military or the first response emergency services. For military applications, one of the key performance requirements is the availability of the positioning solutions for all kinds of dynamics in different environments. Furthermore, due to the stealth requirement in some military actions, it is impossible for military vehicles or personnel to emit signals which enable to be detected by their opponents. This limitation prevents the use of infrastructure-based cooperative localization techniques. The research work of this paper aims at facing the following challenging issues: firstly, to design a positioning filter which is adaptive to the dynamic changes between walking and driving; secondly, to find an approach that correctly identifies the transition between outdoor and indoor with reduced latency; finally, to construct a loosely coupling GNSS/IMU scheme which takes into account the GNSS signal distortion in indoor and urban spaces. Under this context, we propose a complete indoor-outdoor infrastructure-free positioning prototype including a foot-mounted reference navigation system named Pedestrian Reference System (PERSY) and a Ublox High Sensitivity GNSS (HSGNSS) receiver (M8P). A loosely-coupled architecture between GNSS receiver and the PERSY is employed by using an indicator of horizontal position accuracy $\backslash$textitPACCH provided by the GNSS Ublox M8P receiver. This indicator allows qualifying the position solutions delivered by the GNSS receiver as well as detecting the transition of indoor/outdoor, which helps the PERSY to update with absolute positions from GNSS. This positioning prototype can take advantage of both GNSS and PERSY so as to realize a seamless indoor-outdoor positioning for pedestrians and vehicles. The proposed system is evaluated in two scenarios over respectively 2.17 km and 2.68 km including indoor , outdoor and in-vehicle phases. The median horizontal position errors for the two scenarios are respectively 2.23 m and 1.93 m.

59e congrès annuel du club EEA , RENNES, FRANCE, 12-/06/2019 - 12/06/2019; Présentation d'actions IFSTTAR sur le déploiement des véhicules autonomes, aspects industrialisation, recherche et enseignement.

This document is the deliverable D4.2-Technical Specification of the Survey Toolset where the outcome of the work performed in WP4.2 of the ERSAT GGC project is described. This document follows up the work performed in WP4.1 and reported in the deliverable D4.1, extending the ongoing general definition of the track area classification process. The goal of WP4.2 is the specification and development of the toolset for the survey and classification of track areas, giving the system overview and providing the different interacting blocks as the measurement hardware system, the processing software toolbox and the final classification data. Regarding this D4.2, the functional and technical specifications of the toolset are here provided with the description of the interfaces between the different detection techniques and decision logic blocks. Outcome of D4.3 will be the prototype implementation and installation. The document also includes the specification of the measurement system and hardware to be used in the survey process so that the necessary data for the classification techniques can be collected in the railway scenario. Finally, the specification of the output data - the track area classification results - is also analysed and provided. The specification of the survey measurement system and software toolset addressed in the current document will support the next project activities related to the development of the software tools for the classification of track areas in WP4.2 and the execution of measurement campaigns in WP4.3.

This document is the deliverable D4.3-Prototype Implementation of the Survey Toolset, which provides a high level description of the Toolset Prototype. This document is released in a pre-final version, where the toolset implementation has been done using demo data coming from RFI-ASTS private campaign in Italy. The dataset, related to the Pinerolo-Torino line, was used to test and debug the toolset, and the results provided in this document refer to that line and campaign. The Consortium thanks RFI, ASTS and TRI for the investment done to this aim and the availability of needed dataset in order to respect the scheduling of the project. The toolset will be definitively designed after the test campaigns on field, which will confirm the assumptions and in particular the decision logic approach. In fact, once the test campaigns foreseen in the ERSAT GGC will be performed - as planned in the WP4.3 task - the final implementation of the toolset prototype will be released based on those data. A conclusive issue of this deliverable will be then provided with the results of the test campaigns.

This document reports the execution of the track area classification process developed during the work package « WP4 Track Survey and Track Classification » along with the main outcomes and results obtained during this process. The goal of WP4 is to set up a standard measurement and classification system that is able to provide a prediction of the expected presence of GNSS hazard causes and degraded performance to be expected at a given track area, in order to enable the evaluation if the specific environment is suitable or not to place virtual balises or on the contrary should be discarded beforehand. In this document, we detail the results of applying the classification standard process, by means of the developed software Toolset to the measurement data collected in the three measurements campaigns during ERSAT GGC project. This execution report addressed the main important aspects that need to be carried out for the correct application of the classification process and the results obtained with the data collected.

This is the deliverable D4.5 Process Execution Report of the ERSAT GGC project. This document reports the execution of the track area classification process developed during the work package WP4 Track Survey and Track Classification along with the main outcomes and results obtained during this process. The goal of WP4 is to set up a standard measurement and classification system that is able to provide a prediction of the expected presence of GNSS hazard causes and degraded performance to be expected at a given track area, in order to enable the evaluation if the specific environment is suitable or not to place virtual balises or on the contrary should be discarded beforehand. In this document, we detail the results of applying the classification standard process, by means of the developed software Toolset to the measurement data collected in the three measurements campaigns during ERSAT GGC project. This execution report addressed the main important aspects that need to be carried out for the correct application of the classification process and the results obtained with the data collected.

IEEE RTSI 2018, 4th International Forum on Research and Technologies for Society and Industry, Palerme, ITALIE, 10-/09/2018 - 13/09/2018; Global Navigation Satellite Systems (GNSS) have continually involved in our daily life in the past decades. Among all these GNSS-based applications, there is an increasing number of GNSS-based urban transport applications, especially the critical liability ones, such as the Electronic Toll Collection (ETC) and the Intelligent Transport System (ITS). For these GNSS-based applications, not only positioning accuracy but also its reliability is required. Latter has attracted more and more attention from urban GNSS users. Yet urban environments present great challenges for common commercial GNSS receivers since the existence of local effects such as multipath and the Non-Line-of-Sight (NLOS) receptions. The main objective of this paper is to investigate the integrity performance one can expect from a lowcost common GNSS receiver. Under this framework, this paper proposes an innovation-based integrity monitoring scheme by using an Extended Kalman Filter (EKF) with the help of carrierpower-to-noise ratio (C/N0) weighting. The derivations of the Horizontal Protection Level (HPL) for the EKF innovation-based integrity monitoring is also presented in detail. The accuracy and integrity performances are evaluated with real GPS data collected in urban environments. Compared to the classic residual-based snapshot Receiver Autonomous Integrity Monitoring (RAIM), the innovation-based EKF integrity monitoring scheme presents more advantages in terms of accuracy and integrity. With the real dataset collected in urban canyon of Nantes center, the results show that the average size of horizontal position error has been reduced by 1.15 meter with the proposed approach compared to the classic weighted RAIM, the median size of HPL has been reduced by 7.5 meters and the algorithm availability is 100% instead of 98.57%.

Fourth International Conference on Railway Technology: Research, Development and Maintenance, Sitges, ESPAGNE, 03-/09/2018 - 07/09/2018; Présentation de l'architecture développée pour le projet ERSAT GGC utilisant l'image pour la caractérisation de la réception des signaux GNSS le long d'une voie.

TRA 2018, 7th Transport Research Arena, Vienne, AUTRICHE, 16-/04/2018 - 19/04/2018; Cet article présente un résumé de l'état de l'art réalisé pour le projet EU STARS sur l'utilisation d'EGNOS dans le domine ferroviaire. GNSS is expected to help the railway system to be modernized. However, such localization applications requires a high level of accuracy and safety that deserve to use the best potential of satellite-based technologies. The augmentation systems, as the satellite-based augmentation system EGNOS (European Geostationary Navigation Overlay Service), helps to increase the nominal performance. One of the tasks of the EU STARS project deals with the study of the usability of EGNOS in railway environments. EGNOS has indeed been developed driven by the requirements of civil aviation safety procedures in conditions for signal reception that differ from the railway ones. In this paper, after introducing the needs and the basic principles of these systems, we describe the limitations caused by the specificities of railways and some solutions perspectives proposed by the project.

International Congress on High-speed Rail: technologies and long term impacts, Madrid, ESPAGNE, 04-/10/2017 - 06/10/2017; High Speed Railway services have shown that Railways are a competitive and, at the same time, an environmentally friendly transport system. The next level of improvement will be a higher degree of automation, with partial or complete automatic train operation up to fully automatic unattended driverless operation to reduce energy consumption and noise, as well as improving punctuality and comfort. Based on extensive experience in separated railway systems such as Metros, VAL (Véhicule automatique léger) and subways, today's discussion focuses on the fully automatic train operation on regular railway lines. This introduces some questions that are more complex than in today's systems: the performance, length and weight of the trains spreads in a wider range; there are other and more complex operations; components such as level crossings in different equipment variants are added; requirements are higher and the technological equipment point is more heterogeneous. Many evolutionary or innovative approaches for railway automation rely on precise and reliable localization. Especially for higher levels of automation it is essential. Starting from existing technologies such as the European Train Control System (ETCS), moving on to advanced driver assistance systems for local automatic operation up to full automatic train operation (ATO), all of these solutions depend on knowledge of the position of the train on the network. Improved concepts for railway operation e.g. using moving block, on-board integrity supervision or virtual train sets will result in even higher requirements for accuracy and reliability of the localization. The contribution shows an approach based on Global Navigation Satellite Systems (GNSS) as a priority source of information used in combination with sensor data fusion. Elements such as trackside augmentation as well as the use of digital maps will be discussed. Different approaches are considered, e.g. those currently under development by projects in the innovation program in the joint undertaking Shift2Rail.

The objective of the internship is to implement different weighting schemes i.e. i) Elevation and ii) CN0 as well as fault detection and exclusion (FDE) algorithms i.e. Local test and ii) forward back test to evaluate performance of real datasets. The prime focus is to detect how the local effects encountered in the railway environment impact the positioning solution and what could be done to reduce these errors thanks to weighting and FDE solutions.

In order to apply the Enhanced ERTMS/ETCS Functional Architecture, capable of using GNSS and Public Radio TLC Technologies, the safety aspects of the ERTMS/ETCS system upon the future application of the above mentioned positioning and communication technologies have to be investigated. This document describes the Quantitative Safety and Hazard Analysis carried out in ERSAT GGC WP3 - Task 3.2 and reports the relative results.

The deliverable D4.1 Procedure Specification Document of the ERSAT-GGC project is related to the work performed in Task 4.1. The aim of WP4 is to set up a standard measured system that is able to provide a forecast method for the GNSS service performance to be expected at a given track point, in order to enable evaluation whether the specific scenario is favourable to place virtual balises or on the contrary should be discarded beforehand. The results of this assessment can be included in a database map where geo-referenced GNSS quality data is stored. Users may access the information via specified interfaces using standardized communication channels. In order to set up the system, at first a standardized process has to be defined and specified that will determine what has to be measured under which conditions and what has to be simulated for GNSS characterizing along the line. This is the scope of Task 4.1. In order to set the context of the work, a description of the need and importance of a standard process to classify the track areas for virtual balise placement is given in the introduction. Later, a first version of the high level requirements to the classification process is provided. Based on these requirements a preliminary study of the different techniques, measurements and parameters that are relevant to define a safe track area classification standard process has been performed. The document then focus on a detail description on the GNSS detection techniques that are relevant for the standard process and the track area classification criteria. Further works related to the detection and classification criteria are required, and they will be included in the next deliverable D4.2, which specifies the dedicated requirements for the toolset.The standard process will undergo reviews until the execution and test: all these improvements and the related links to the toolset development will be covered by the next deliverables of WP4.

RAIL Live 2018, Bilbao, ESPAGNE, 18-/04/2018 - 19/04/2018; Présentation de l'état de l'art des applications GNSS pour le ferroviaire, des enjeux et des verrous. Industry update: the state of GNSS-based solutions and projects for rail. Understanding the implications of GNSS for the rail industry: optimising operations and reducing costs. Remaining issues and next short term steps: developing tools and methodology to enhance and prove both the reliability and safety of GNSS-based positioning solutions

Data Science and Mobility Conference, Lausanne, SUISSE, 31-/01/2018 - 31/01/2018; Medium of presentation for exchanging with the audience during the workshop 4 of the Data Science and Mobility Conference: Navigation technologies and Geographic Information System (GIS) for a better traffic management

The use of global navigation satellite systems (GNSS) will provide significant advantages for ensuring the control of train movements on railway networks equipped with European Rail Traffic Management System/European Train Control System (ERTMS/ETCS). Indeed, this disruptive technology can play an important role for reducing the rail infrastructure's equipment by enabling trains to determine their position in an autonomous way. Specific associated hazards have to be considered in the European signaling system. From this perspective, performances of GNSS-based localization systems were analyzed in different past studies. They highlighted what they can bring to the railway domain. For going further than performance-centric analyses to help inserting these systems safely in rail applications, this paper want also to focus on their operating uses. For that, the safety evaluation proposed in this paper is able to handle specific estimated confidence-related data that are associated to an estimated position. This paper first details the managed risks in ETCS due to the localization function with, in particular, those that may arise due to GNSS-based systems. It discusses the evolution of these risks when dealing with moving block operation of the ETCS-level 3. The safety evaluation approach is then explained. It relies in fact on extended integrity data handled in the case of the train spacing. Finally, it is applied in different operational cases to show evaluation results when real GNSS data are measured in a railway environment.

Les applications des systèmes de positionnement par satellites (ou GNSS - Global Navigation Satellite System) ont progressivement envahi les systèmes de transport et les applications mobiles. Les applications déployées sont peu exigeantes en termes de performance : elles tolèrent une certaine imprécision et ne requièrent pas nécessairement une grande confiance dans l'information délivrée. Avec l'arrivée des véhicules autonomes ou les évolutions des systèmes de signalisation ferroviaire, de nouveaux besoins sont exprimés : une plus grande précision assortie d'un indicateur de confiance dans l'information fournie, en particulier pour des applications qui mettent en jeu la sécurité des biens et des personnes. Un récepteur GNSS utilise la mesure simultanée de 4 (au moins) temps de propagation des signaux issus de 4 satellites différents pour estimer sa position. Dans les environnements traversés par les systèmes de transports, la réception de ces signaux est fréquemment sujette à des conditions de réception difficiles liées à la présence d'obstacles proches de l'antenne de réception (blocage, réflexion, diffraction) qui engendrent indisponibilité, retards de propagation et donc, erreurs sur le calcul de la position. Pour comprendre les causes et les conséquences des erreurs introduites par le canal de propagation radio sur les performances de localisation, les travaux présentés dans ce mémoire de HDR rassemblent les travaux menés selon 3 axes principaux. Dans ces travaux, nous avons ainsi analysé les effets du canal de propagation radio sur le signal reçu par l'antenne du récepteur GNSS, caractérisé et quantifié la qualité du signal reçu en sortie du récepteur, proposé des méthodes originales permettant de modéliser et pallier les erreurs de localisation et enfin nous avons contribué au développement d'une méthodologie d'analyse de la sûreté de fonctionnement du système de localisation dans le domaine ferroviaire. L'erreur que nous cherchons à réduire en particulier est l'erreur engendrée par les phénomènes de propagation locaux et en particulier par l'utilisation des signaux reçus après réflexions et en l'absence de signal direct, encore appelés NLOS (Non-Line-Of-Sight). Parmi les résultats, nous avons mis en oeuvre des techniques de traitement d'images pour une détection déterministe associée à des techniques d'exclusion et de pondération des signaux reçus. Avec des techniques de traitement du signal, nous avons proposé des méthodes d'estimation dynamique des retards de propagation qui ont montré leur efficacité dans la réduction des imprécisions sur les calculs de la position en milieux urbains. Enfin, nous abordons le concept d'intégrité de la position. Les processus de surveillance de l'intégrité sont aujourd'hui issus de l'aéronautique et s'adaptent mal aux conditions de réception en milieu urbain. Notre connaissance des conditions de propagation des signaux nous a conduits à étudier et à proposer de nouveaux processus pour borner les erreurs de position introduites par l'environnement urbain. Enfin, nous présentons les axes de recherche mis en oeuvre afin de contribuer à l'introduction des solutions GNSS pour des applications de signalisation ferroviaire : nos travaux portent sur l'adaptation des méthodologies classiques ferroviaires au système GNSS et à ses sources de dégradation.

Young researcher Seminar 2017, Berlin, Allemagne, 15-/05/2017 - 18/05/2017; From road guidance applications to locomotives or road vehicles fleet management, Global Navigation Satellite System (GNSS)-based positioning systems are more and more spread and used. However, the urban environment presents great challenges for GNSS positioning since number of obstacles result in signal attenuations and blockages, which can cause large errors. Yet, for new GNSS land applications, knowing the certainty of one's localization is of great importance if we want to rely on it for toll, insurance or for railway signaling. The concept of GNSS integrity, which is defined as a measure of trust to be placed in the correctness of the information supplied by the total system, can help to meet this requirement. Although GNSS integrity has been firstly developed and formalized in the aviation field, the algorithms developed for the aerospace domain cannot be introduced directly to the GNSS land applications. This is because a high data redundancy exists in the aviation domain and a basic hypothesis that only one failure occurs at a time is made for aviation schemes, which are not the case for the urban users. It is a great challenge to extend the integrity monitoring algorithms to GNSS urban applications. This paper will highlight the need for new integrity monitoring systems and will illustrate the behaviour of existing solutions based on real data. In this paper, we will in particular compare and evaluate the performances of several Fault Detection and Exclusion (FDE) integrity monitoring algorithms as well as different weighting models.

European Navigation Conference, LAUSANNE, SUISSE, 09-/05/2017 - 12/05/2017; The evolution of smartphones and their embedded sensors motivates research toward the development of handheld device based navigation solutions especially for harsh environments. In this context, Pedestrian Dead Reckoning is usually adopted to compute the pedestrian's trajectory. Step/stride lengths and walking directions are combined in a recursive process. Unfortunately the estimated path suffers from drifting errors due to the sensors' nature and the motion complexity. To reduce this error, map matching strategies are studied and several solutions are proposed in the literature. In this work a Matching Filter is proposed to mitigate the drifting errors. The Matching Filter is a nest filter based on an extended Kalman Filter and a Complementary filter. The key idea is to match the PDR trajectory with the standalone GPS trajectory during opportune phases in order to estimate a global heading and scale factor errors on the PDR path. The proposed strategy is tested with a 1km walk in a shopping center. A 75% improvement is found as compared to the PDR only trajectory.

Les applications des systèmes de positionnement par satellites (ou GNSS - Global Navigation Satellite System) ont progressivement envahi les systèmes de transport et les applications mobiles. Les applications déployées sont peu exigeantes en termes de performance : elles tolèrent une certaine imprécision et ne requièrent pas nécessairement une grande confiance dans l'information délivrée. Avec l'arrivée des véhicules autonomes ou les évolutions des systèmes de signalisation ferroviaire, de nouveaux besoins sont exprimés : une plus grande précision assortie d'un indicateur de confiance dans l'information fournie, en particulier pour des applications qui mettent en jeu la sécurité des biens et des personnes. Un récepteur GNSS utilise la mesure simultanée de 4 (au moins) temps de propagation des signaux issus de 4 satellites différents pour estimer sa position. Dans les environnements traversés par les systèmes de transports, la réception de ces signaux est fréquemment sujette à des conditions de réception difficiles liées à la présence d'obstacles proches de l'antenne de réception (blocage, réflexion, diffraction) qui engendrent indisponibilité, retards de propagation et donc, erreurs sur le calcul de la position. Pour comprendre les causes et les conséquences des erreurs introduites par le canal de propagation radio sur les performances de localisation, les travaux présentés dans ce mémoire de HDR rassemblent les travaux menés selon 3 axes principaux. Dans ces travaux, nous avons ainsi analysé les effets du canal de propagation radio sur le signal reçu par l'antenne du récepteur GNSS, caractérisé et quantifié la qualité du signal reçu en sortie du récepteur, proposé des méthodes originales permettant de modéliser et pallier les erreurs de localisation et enfin nous avons contribué au développement d'une méthodologie d'analyse de la sûreté de fonctionnement du système de localisation dans le domaine ferroviaire. L'erreur que nous cherchons à réduire en particulier est l'erreur engendrée par les phénomènes de propagation locaux et en particulier par l'utilisation des signaux reçus après réflexions et en l'absence de signal direct, encore appelés NLOS (Non-Line-Of-Sight). Parmi les résultats, nous avons mis en oeuvre des techniques de traitement d'images pour une détection déterministe associée à des techniques d'exclusion et de pondération des signaux reçus. Avec des techniques de traitement du signal, nous avons proposé des méthodes d'estimation dynamique des retards de propagation qui ont montré leur efficacité dans la réduction des imprécisions sur les calculs de la position en milieux urbains. Enfin, nous abordons le concept d'intégrité de la position. Les processus de surveillance de l'intégrité sont aujourd'hui issus de l'aéronautique et s'adaptent mal aux conditions de réception en milieu urbain. Notre connaissance des conditions de propagation des signaux nous a conduits à étudier et à proposer de nouveaux processus pour borner les erreurs de position introduites par l'environnement urbain. Enfin, nous présentons les axes de recherche mis en oeuvre afin de contribuer à l'introduction des solutions GNSS pour des applications de signalisation ferroviaire : nos travaux portent sur l'adaptation des méthodologies classiques ferroviaires au système GNSS et à ses sources de dégradation.

Institute of navigation - International Technical Meetings - ION ITM 2017, Monterey, Etats-Unis, 30-/01/2017 - 02/02/2017; Integrity is one of the most important parameters characterizing the Global Navigation Satellite Systems (GNSS) performance for safety-related applications. It is defined as a measure of trust to be placed in the correctness of the information supplied by the total system. This concept is more and more important, especially for applications in urban environment with standalone GNSS system, where GNSS performance is strongly degraded by the signal propagation conditions. Non line of Sight (NLOS) signals, caused by the surrounding obstacles, are of particular interest, as the error they induced remains a large cause of inaccuracy. In order to get rid of these constraints and to guarantee a better performance of positioning accuracy as well as integrity, several approaches can be used, such as positioning weighting models, 3D city models, Fault Detection and Exclusion (FDE) techniques etc. Since the concepts of integrity and accuracy are strongly related to each other, a better accuracy can help to improve the integrity performance. Thus, to reduce and to bound position errors are our two main objectives. In the work presented here, we will introduce 2 classes of methods which contribute to the NLOS signal mitigation as well as integrity performance. The first class concerns the use of different weighting models in order to reduce the influence of the NLOS on the overall measurements. The second class consists of Fault Detection and Exclusion (FDE) algorithms which allow users to identify and remove the outliers.

Séminaire Ferroviaire et Applications GNSS, Toulouse, FRANCE, 24-/03/2016 - 24/03/2016; Cette présentation fait l'état des lieux des projets passés visant l'introduction du GNSS dans le ferroviaire : enjeux, bilan et verrous restant.

Les nouveaux services de transport intelligent foisonnent. La plupart d'entre eux reposent de façon plus ou moins directe sur une information de localisation, parmi lesquelles les services de navigation bien sûr, mais aussi de l'aide à l'éco-conduite, des assurances « pay as you drive », la limitation de vitesse variable... Techniquement, la solution la plus répandue aujourd'hui repose sur l'installation de puces GPS à bord des véhicules, agrémentée des équipements logiciels et matériels capables d'exploiter l'information de position pour délivrer un service (calcul d'itinéraire, recalage sur la carte, système de communication etc). Le système de radionavigation par satellites GPS offre en effet le meilleur compromis coût/simplicité/performance aujourd'hui. Il peut être complété par l'utilisation de signaux EGNOS, améliorant ainsi sa précision et sera bientôt compatible avec Galileo. Certains services, tels que la navigation automobile, s'accommodent aujourd'hui assez bien des performances obtenues. Malheureusement, alors que l'utilisateur urbain d'un système de localisation par satellites est le plus demandeur de précision, il dispose d'un service dégradé en raison des conditions de propagation des signaux, fortement liées à la densité des obstacles, qui limitent les performances optimales atteignables. Pour améliorer les performances, en termes de précision, disponibilité et d'intégrité (c'est-à-dire de garantie de service), les travaux menés dans les laboratoires Leost et Geoloc de l'Ifsttar exploitent la connaissance de l'environnement de réception proche afin de réduire les perturbations sur la localisation GNSS. Dans le projet CAPLOC, cette connaissance est extraite d'une analyse d'images de l'environnement au-dessus du véhicule ; dans INTURB d'une carte numérique 3D. Ces deux approches innovantes s'inscrivent dans la suite d'un brevet déposé en 2006 pour CAPLOC et dans un courant de propositions utilisant les modèles 3D de plus en plus disponibles et complets. Le rapport proposé en livrable synthétisera l'ensemble des travaux publiés et décrira en particulier les approches suivies dans ces deux projets, illustrées chacune par des résultats expérimentaux.

Course Content: Context of the Inertial Navigation System (INS), the challenge of personal navigation with a handheld device and alternative positioning strategies., Contenu du cours: Contexte du système de navigation inertielle (INS), le défi de la navigation personnelle avec un appareil portable et les stratégies de positionnement alternatives

IC-ARE'15, International Congress on Advanced Railway Engineering, Istanbul, TURQUIE, 02-/03/2015 - 04/03/2015; In this paper the results of the EU-funded project GaLoROI (Galileo Localization for Railway Operation Innovation) are presented. The satellite based localization unit for railways developed within GaLoROI serves as a basis for modern train control systems allowing a safe and precise continuous localization of trains increasing the capacity and operational performance of railways in comparison to current discrete train localization methods.GaLoROI started with the specifications of the localization unit which represent the state of the art of both railway and GNSS technology. Based on these specifications, the product development including system integration, verification and validation has been carried out with the target to reach the high safety level of SIL 3 specified in railway standardisation. The development was followed by tests and demonstration runs. It was accompanied by a RAMS performance analysis and an economical assessment. The results from the safety perspective have been summarized and reflected in the safety case and the assessment of the safety case.These results of GaLoROI are presented in this paper. They are a unique step in the field of satellite based localization for railways. Prior to GaLoROI, only the viability of satellite based localization in railways could be demonstrated. In GaLoROI it has been shown that satellite based localization is able to provide a precise and safe localization following the demonstration processes required by the railway safety standards.

IPIN Conference, MONTBELIARD, FRANCE, 28-/10/2013 - 30/10/2013; Le positionnement et la navigation à l'intérieur des bâtiments est un élément moteur de la promotion du transport actif

For new ITS applications, positioning solutions will require to be more accurate and available. The most common technique used today is composed of a GPS receiver, sometimes aided by other sensors. GPS, and GNSS in general, suffer from masking effects and propagation disturbances in urban areas that cause biases on pseudo range measurements. Mitigation solutions sometimes propose to detect and exclude outliers but in land transportation applications, such a decision reduces dramatically the service availability and thus, the interest of satellite-based solutions. In order to optimize the use the satellites received, we propose a new positioning algorithm based on signals only with pseudo range error modeling in association with an adapted filtering process. The model and the filter have been validated with simulation data performed along an urban bus line and have shown that both positioning error and availability can be improved. Along the trajectory tested, the mean accuracy has been reduced from 5.3m with a classical filter to 2.6m with our algorithm with 89% of the points more accurate than 5 meters instead of 64% before.; For new ITS applications, positioning solutions will require to be more accurate and available. The most common technique used today is composed of a GPS receiver, sometimes aided by other sensors. GPS, and GNSS in general, suffer from masking effects and propagation disturbances in urban areas that cause biases on pseudo range measurements. Mitigation solutions sometimes propose to detect and exclude outliers but in land transportation applications, such a decision reduces dramatically the service availability and thus, the interest of satellite-based solutions. In order to optimize the use the satellites received, we propose a new positioning algorithm based on signals only with pseudo range error modeling in association with an adapted filtering process. The model and the filter have been validated with simulation data performed along an urban bus line and have shown that both positioning error and availability can be improved. Along the trajectory tested, the mean accuracy has been reduced from 5.3m with a classical filter to 2.6m with our algorithm with 89% of the points more accurate than 5 meters instead of 64% before.

In the frame of GATE4Rail project, Work Package (WP) 3 deals with the definition of a comprehensive methodology and the associated tools able to characterise the GNSS performance into the railways application scenarios defined in WP2 in the framework of a Virtual Balise detection in ETCS/ERTMS context. The present document (deliverable D3.1) is the first report delivered by GATE4Rail WP3. It is specifically dedicated to the definition of a standardised database in order to characterize GNSS in different rail scenarios and the description of Consortium tools included in the GATE4Rail test-bed able to generate local and global hazards and evaluate their impact on GNSS performance

TRA 2022, Transport Research Arena, Lisbonne, PORTUGAL, 14-/11/2022 - 17/11/2022; GNSS are now in everybody's pocket, embedded in our smartphones and is widely used for informative uses (navigation, leisure...). In future transportation modes, and in particular autonomous vehicles or for safety related railways applications, localisation needs to be accurate and/or safe and trustful. In many of the environments crossed by users, satellite signal propagation is disturbed by buildings, trees or other obstacles that degrade performance. To contribute to the development of safe and accurate localisation solutions in these environments, the LOCSP project intends to evaluate and compare past algorithms on a new shared database but also focuses on the development of two research proposals: through cooperative vehicle localisation using artificial intelligence and with interference mitigation. This paper aims to introduce the project and the first results on these two axes

WCRR 2022, World Congress on Railway Research, Birmingham, ROYAUME-UNI, 06-/06/2022 - 10/06/2022; Novel signalling systems are expected to use Digital Maps to implement Automatic Train Operation (ATO) functions or to augment technologies such as European Global Navigation Satellite Systems (EGNSS), inertial sensors or optical sensors for localization purposes. However, the construction of a Digital Map requires with current technologies expensive railway surveying campaigns. Additionally, the cost for their maintenance and update is a major challenge that prevents its adoption. With regard to the evolution of Control-Command and Signalling (CCS) systems, a new verification infrastructure is also needed to characterize new on-board solutions in terms of train position, speed and acceleration errors, as well as to assess their expected performance. Our research, on one side, aims to develop a methodology and related toolset for executing railway surveying, building and maintaining Digital Maps based on the post-processing of data recorded by trains in commercial service, equipped with Commercial Off The Shelf (COTS) sensors like GNSS receivers, cameras, Inertial Measurement Units (IMUs), and LIDARs. On the other side, a similar approach and development can be used to provide « high precision and high accuracy ground truth reference data » as true values for carrying out error and performance analysis. This Ground Truth methodology does not require installation of trackside equipment or modifications to existing trackside signalling systems and a-priori knowledge of track databases. This paper summarizes the main user needs of (1) the use of Digital Maps for signalling subsystems purposes, (2) the availability of innovative Ground Truth sources for performance assessments. These user needs are essential for the future design of such methodologies and toolsets.