A minimal HiL architecture for railway signalling system testing

This work presents a simulation environment for railway operation, focusing on a comparison between Fixed Block (FB) and Moving Block (MB) signalling systems. The simulator incorporates a model of the Radio Block Centre (RBC), to generate appropriate Movement Authorities (MAs) according to the selected signalling approach, and of the On-Board Units (OBUs) that compute reference speed profiles based on infrastructure constraints, signalling-induced deceleration and other disturbances. To enhance realism and applicability, a minimal Hardware-in-the-Loop (HiL) architecture was implemented by deploying one OBU on an external device. Then, simple yet representative scenarios were designed, involving two consecutive trains travelling between two stations with variations in initial headway and motion disturbances affecting the leading train. The impact of the signalling system on train motion was investigated: precisely, simulation results confirmed that MB system outperforms FB under degraded conditions, demonstrating higher Traffic Capacity (TC) and improved Motion Regularity (MR) compared to FB. These findings highlight the potential ability of MB signalling to better accommodate perturbations and support shorter headways, enhancing operational efficiency. Future developments will enhance the HiL setup with more complex train models and human-machine interactions, aiming to increase simulation fidelity and operational relevance.