Toward Automatic Train Operation for GoA3/4: Novel Architecture and Applicability Criteria of Speed Profile Optimization Strategies

The railway industry is increasingly focusing on advancing Automatic Train Operation (ATO) technologies to achieve higher Grade of Automation (GoA) while addressing the significant challenges associated with integrating these advancements into existing infrastructure. This study introduces a novel reference architecture for the ATO system developed within the X2Rail-4 project, which delineates new components, interfaces, and terminology to support GoA3/4 levels. Within this architecture, ATO distinguishes two main control layers: a high-level controller responsible for computing the Optimal Speed Profile (OSP), and a low-level controller tasked with executing traction and braking commands. This study concentrates on the high-level control layer, offering a comprehensive analysis of speed profile optimization strategies and single-train dynamic models based on a review of 45 selected studies. In order to assess and evaluate the relevance of the reviewed studies within GoA3/4 contexts, a set of applicability criteria was introduced. This analysis identified current limitations in achieving full automation and highlighted promising avenues for future research. These findings serve as the foundation for a targeted research agenda aimed at advancing GoA3/4 readiness.