GNSS, IMU, camera and LIDAR technology characterization for railway ground truth and digital map generation

Satellite navigation in combination with affordable onboard sensors are key enabling technologies to support the digitalization in railway transport. However, the adoption of these technologies still requires common methodologies to evaluate anywhere the positioning performance. For this, the comparison with a reference ground truth as well as the availability of digital railway maps is necessary. However, the development of a reliable Ground Truth and Digital Map solutions based on affordable onboard sensors requires on its side first a rigorous characterization of each sensor technology. This paper provides with the most important aspects for the characterization of GNSS, IMU, Camera and LIDAR technologies for its use in railway environment within the context of the European RAILGAP project

Framework to Classify Railway Track Areas According to Local GNSS Threats

In this paper we present a modular framework to classify railway track areas regarding the expected presence of local GNSS threats. This information might be critical for a safe signalling operation, for example to determine where virtual balises could be placed safely. We show first how different GNSS threats can be detected using dedicated detection algorithms and how these individual detection results can be then transformed from time to the track domain. An overall decision logic is subsequently used to identify an area as suitable or unsuitable for GNSS usage by combining all available GNSS data collected over the same track area. Finally, the framework implementation is evaluated with railway data obtained during a measurement campaign in Sardinia, Italy in 2019. Even though developed in the railway context, the presented framework architecture and methodology may be also considered to perform similar classification tasks for other means of transport

On the GNSS augmentation services for the ERTMS train control and Connected Car applications: technical synergies and opportunities

The Rail and Road transportation systems are evolving to progressively introduce automation with the ultimate goal of autonomous driving. The expectations are to improve efficiency and to guarantee higher level of safety. As transport networks will evolve towards high mobility, vehicles will become connected and self-positioned opening new challenges to comply with stringent safety requirements. Although vehicles are increasingly equipped with multiple advanced onboard positioning sensors, GNSS corrections allow to minimize the confidence error and to standardize the on board units. In the ERTMS (European Railways Train Management System) GNSS positioning must comply with the Tolerable Hazard Rate of 10E-9/hour at system level. Similar requirements are targeted by the connected cars when the management of vehicles is performed by a centralized authority as in the ERTMS system. Both ERTMS and Connected Car applications rely on the knowledge of the vehicle’s position with similar integrity levels. Considering also that rail and roads are frequently close to each other’s sharing the same operational environment, a multimodal augmentation network has been designed in the HELMET project to satisfy the new market needs. The aim of this paper is to assess the technical feasibility and the economic sustainability of this multi-modal augmentation network designed for the rail and road applications. The prerequisites are to reuse existing and future EGNSS infrastructures - without creating a direct dependence on themselves - to guarantee the interoperability and to allow a stepped deployment in line with the plans of the rail and road infrastructure managers. The paper includes the results of a recently concluded field test and the requirements of RFI – the Italian railways infrastructure manager who is managing a working group with rail industries to contributing to a standardizable and interoperable GNSS-based ERTMS system. Follow up activities to consolidate results for an operational system are on-going

Detection of GNSS Interference in Safety Critical Railway Applications using Commercial Receivers

Satellite navigation plays a critical role in new railway signaling and train control systems. It will allow higher levels of automation at a reduce cost in installation and maintenance as compared to current infrastructure-based technologies. However, in order to be integrated in railway systems, GNSS must guarantee the stringent railway safety requirements. GNSS safety has been extensively quantified for the aviation community, however, in the railway environment the probability of local GNSS hazards like interferences is larger due to its operation in a non-restricted space. Railway GNSS receivers must be therefore equipped with mechanisms to protect the position determination from being corrupted by undesired interferences (jamming or spoofing) without being aware of it. In this paper and based on Commercial-Off-The-Shelf (COTS) hardware we implemented interference detection functions suitable for railway localization. We detail the algorithm design as well as the necessary calibration procedure to determine the nominal signal model. The performance of the interference detection is analyzed with an experimental setup on a commercial train during the measurement campaign organized for the EU project ERSAT-GGC. Figures about the detection capability and detected events along the selected line are finally provided

GNSS, IMU, Camera and LIDAR Technology Characterization for Railway Ground Truth and Digital Map Generation

Satellite navigation in combination with affordable onboard sensors are key enabling technologies to support the digitalisation in railway transport. However, the adoption of these technologies still requires common methodologies to evaluate anywhere the positioning performance. For this, the comparison with a reference ground truth as well as the availability of digital railway maps is necessary. However, the development of a reliable Ground Truth and Digital Map solutions based on affordable onboard sensors requires on its side first a rigorous characterization of each sensor technology. This paper provides with the most important aspects for the characterization of GNSS, IMU, Camera and LIDAR technologies for its use in railway environment within the context of the European RAILGAP projec

Local GNSS Threat Detection Methods for Virtual Balise Placement in Railway Applications

The introduction of the GNSS positioning technology into the evolution of ERTMS/ETCS is based on the concept of virtual balise to minimize the impact onto existing ERTMS solutions. The detection of virtual balises is foreseen by using GNSS in combination with odometry information or other kinematic sensors. However, the presence of local GNSS threats (e.g, multipath, NLOS or interference) may lead to errors in the pseudorange measurement that cannot be neither corrected by local or wide-area augmentation systems nor properly bounded, and will lead ultimately to an error in the virtual balise position that cannot be bounded with the required integrity. In order to a priori prevent the risk of this hazardous situation, virtual balises must be logically located in areas where there are not local threats that may lead a Virtual Balise Transmission System on board the train to dynamically estimate unbounded virtual balise position errors. This paper summarizes the initial work performed in the H2020 GSA Project ERSAT-GGC with respect to the different techniques that can be used to detect local GNSS threats and that can support a later classification of railway areas as suitable or not suitable for placing virtual balises

Classification of Railway tracks for applying enhanced ERTMS/ETCS Solutions Based on GNSS positioning technologies

WCRR 2019, 12th World Congress on Railway Research, Tokyo, JAPON, 28-/10/2019 - 01/11/2019The 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

Classification of Railway tracks for applying enhanced ERTMS/ETCS Solutions Based on GNSS positioning technologies

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

Applicazioni ERTMS/ETCS Basate Sulla Tecnologia Di Posizionamento Gnss. Classificazione dell'infrastruttura ferroviaria

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/ETC