This book constitutes the refereed proceedings of the First International Conference on Reliability, Safety, and Security of Railway Systems, RSSRail 2016, held in Paris, France, in June 2016. The 15 revised full papers presented were carefully reviewed and selected from 36 initial submissions. The papers cover a wide range of topics including failure analysis, interlocking verification, formal system specification and refinement, security analysis of ERTMS, safety verification, formalisation of requirements, proof automation, operational security, railway system reliability, risk assessment for ERTMS, and verification of EN-50128 safety requirements.