The project is constituted of 3 successive phases: the elaboration of reference data and characterisation of the railway environment through a measurement campaign, the assessment of the GNSS performances achievable in this environment as well as the possible evolutions of European GNSS services and ERTMS/ETCS functions and the analyses of the economic benefits and possible implementation roadmap.
For the Phase 1: Measurement campaign, in the second period the project has
• Installed the measurement equipment on trains in the three countries and obtained the necessary approvals
• Performed a lot of measurements and significant amounts of high quality GNSS raw data collected.
• Produce Ground Truth data for the test trips, to be used as reference for performance analysis.
• Pre-Processed the collected data as well as Ground Truth to uniform formats in a semi- automated data processing.
• Storage of collected data in standardized file naming and in a harmonized structure to the jointly used cloud storage for analysis.
For the Phase 2: EGNSS Performances assessment, safety requirements and impacts on existing systems, the project has:
• Produced the guidelines for data pre-process and sorting, to allow an efficient analysis of large volumes of data.
• Analysed the recorded data using a variety of techniques.
• Qualified and quantified the environmental influences on GNSS has been qualified and quantified.
• GNSS performance degradation has been correlated to the presence of environmental influences, which can be used to predict GNSS performance
• Analysed local effects which significantly degrade performance, covering urban and mountainous environments and forests.
• shown that current receiver algorithms need to be improved to cope with the railway environment, as the true error is not always bound by the protection level algorithm.
• Analysed the performance of EGNOS in the railway environment and shown that using EGNOS from geostationary satellites is not practical.
• Produced a proposal for the evolution of EGNOS for railway applications which overcomes the limitations identified.
For the Phase 3: Economic Benefits and roadmap, the project has:
• Developed a model to analyse cost – benefit for individual applications, which can be applied for individual analysis with customer and application specific cost and benefit figures.
• Performed a cost benefit analysis showing that a positive Benefit/Cost ratio can be achieved in local and regional lines, but is challenging in mainline applications.
• The sensitivity analysis has shown that the cost of the additional on-board module and the saved balises dominate over the cost of maintaining balises, meaning CAPEX dominate over OPEX.
As summary, the STARS project has shown that there is potential in applying GNSS for safety critical applications in the railway environment. Due to significant impact of local effects on performance resulting from the challenging environment a solution with sensor fusion, and possibly map matching will however be required. Critical will be the generation of initial position fixes at start-up, as local effects are more significant in stations and the impact is more significant at standstill. EGNOS will have to distributed to trains via radio, as the reception from geostationary satellite is severely limited by the environment, with large areas of complete unavailability.
It has been shown that the concept of a MOPS similar to the one in aviation is not suitable for the railway environment, as:
• GNSS is not a continuously working system in the railway environment, but only works intermittently.
• Current algorithms for the calculation of the protection level generated wrong results.
• Local effects cannot be embraced by a simple MOPS, unless worst case values are used across entire lines, which degrades the achievable performance dramatically.
The cost – benefit needs to be analysed, using detailed figures from customers. The questions of network access, as well as interoperability will have to be analysed further.
Regarding the dissemination, the consortium has participated actively in a number of events, trades and conferences where project and its results has been presented. In addition, a Final Book that condenses the main results of the project has been prepared with the inputs provided by the members of the consortia.
The consortium has established a close collaboration with main stakeholders such as GSA and ESA for the exploitation of the results. This collaboration has been materialized in meeting to align and enhance the quality of the outcomes of the project. The exploitation of the work done in future activities is ensured by the public access to the deliverables generated by the consortium.
