AEGIS: Autonomous Embedded Ground-Independent Signalling — Railway Signalling Without Ground Authority

Abstract

This preprint is available in two versions: French (main_fr.pdf / main_fr.tex) and English (main_en.pdf / main_en.tex). The English abstract follows. For over one hundred and fifty years, all railway signalling architectures have rested on a single assumption: safety authority resides in the ground infrastructure. The network authorises; the train obeys. We question its necessity. The physical safety condition is a local property of the train and its environment, verifiable without external authorisation. We propose an architecture — AEGIS (Autonomous Embedded Ground-Independent Signalling) — in which neither primary safety nor installation coordination depends on a centralised ground authority: the ground provides certified data, the train reasons, and installation coordination is handled by a topologically partitioned distributed ledger. We examine the architectural properties arising from this inversion, the emergent properties of the resulting system, and the open questions this new paradigm generates.