GNSS4Rail Simulation tool. Supporting Virtual Balise (VB) location for GNSS based railway operations

The introduction of GNSS (Global Navigation Satellite System) in railway operations has been identified as a cost-effective solution that, along with the European Railway Traffic Management System (ERTMS), leads to harmonize infrastructure and speed up interoperability across Europe. The use of GNSS introduce new concepts such as Virtual Balise (VB) and Ground Truth (GT) along with new procedures which aims to characterize the track and railway environment as a mean to ensure GNSS required performances at VB location in order to meet railway control and safety requirements. One of the main contributors to the GNSS degraded performances in railway operations is related to ground local environmental conditions, in terms of satellite coverage/LOS (line of sight) and GNSS tracked satellite's geometry. This information can be computed and supplemented with satellite healthy information from GNSS web services to forecast basic GNSS performances on a certain location and time. The use of a simulation tool as a preliminary mean to assess the track conditions in terms of GNSS basic required performances is proposed as a powerful and cost saving solution for Virtual Balise (VB) location during the ETCS (European Train Control System) trackside planning phase and pre-tactical railway operations phase.