Towards the Future Generation of Railway Localization and Signaling Exploiting sub-meter RTK GNSS

Internet of Things devices and smart sensors have become increasingly more pervasive in railway transportation applications, where they have the potential to significantly improve reliability, capacity, safety, and to reduce costs. In the 'smart rail' concept a key enabler is the ability to accurately localize trains with centimeter precision. This can be achieved using a combination of a high-precision GNSS-based module capable of achieving sub-meter accuracy and emerging radio and sensor technologies. This paper proposes a train tracking sensor node for in-field assessments fusing the absolute localization data from the GNSS and from local reference systems, such as Real Time Kinematics (RTK) with Inertial Measurement Unit (IMU) and Dead Reckoning (DRK). A complete wireless sensor node has been designed and evaluated in the field for functionality and power consumption. Within the sensor node, two different GNSS modules have been tested, with and without RTK and DRK, under different GNSS coverage conditions in various static and dynamic scenarios. We demonstrate that centimeter accuracy is achievable, with an accuracy of 2 +/- 1 cm under static conditions and perfect satellite visibility, 4 +/- 18 cm and 17 +/- 40 cm under dynamic conditions in perfect and poor coverage conditions, respectively.