Safety Critical Analysis for Communication Between Onboard Train System and Wayside Control Centre in Urban Rail Environment for GNSS-Based Train Localisation System

LRT Kelana Jaya (KLJ Line), an urban rail in Malaysia, has been in operation since 1998 and was the world's longest automated driverless urban rail at the time of its inception. KLJ Line is equipped with a Communication-Based Train Control (CBTC) signalling system, but it does not have a secondary detection system. However, due to an incident in 2021, the accident investigation committee recommended including a secondary detection system for the existing KLJ Line. An alternative secondary detection system using the Global Navigation Satellite System (GNSS) is being proposed using the Public Telecommunication Operator (PTO) as a communication channel between the onboard system and the wayside system in the control centre. This paper focuses on analysing the suitability of PTO communication for safety-critical communication based on the guidelines recommended by the EN 50159 standard. This study is done purely from the protocol stack perspective. Additionally, the performance parameter of the network and physical layers is measured to determine if it meets similar safety-critical systems performance requirements, such as signalling systems. The concept proposed is pending field trial, data collection and analysis of the results. The proposed system is expected to perform to a minimal Safety Integrity Level (SIL)-1 based on a field trial, thus making it safe for its intended purpose.