Critical Material and Component Supply Risks in Railways: From Supply-Chain Vulnerability to O&M Resilience and Operational Mobility Sovereignty — The RMCVI Screening Framework

This independent applied-research working paper investigates how vulnerabilities in critical-material and component supply chains can propagate into railway operations and maintenance (O&M), increase restoration time, affect RAMS performance and operational availability, and ultimately challenge the resilience of essential mobility services. The study shifts the unit of analysis from macroeconomic mineral criticality to functional-chain criticality: material → processing → component → subsystem → spare part → maintenance → availability → continuity of essential service. Five railway case-study families are examined: pantograph contact strips, permanent-magnet traction motors, traction transformers, lithium-ion battery systems and silicon-carbide (SiC) traction power electronics. The publication proposes the Railway Material & Component Vulnerability Index (RMCVI), an exploratory screening framework combining upstream supply risk, functional dependency, non-substitutability risk, qualification rigidity and logistics exposure. The RMCVI is not a standard, certification method, sovereignty metric or validated predictive model; it is a methodological framework intended to be calibrated and validated on industrial data. The paper also introduces the concept of operational mobility sovereignty, used in a deliberately limited analytical sense to describe the ability of transport authorities and operators to sustain essential mobility functions despite external supply-chain disruptions and excessive dependence on non-substitutable industrial nodes. The publication is based on institutional, regulatory, scientific and primary industrial sources and includes traceability notes, reproducibility data for quantitative figures, an evidence scale, railway case studies, a worked illustrative RMCVI calculation and a proposed validation protocol. Edition: English / French / ArabicVersion: 1.0 — First trilingual editionStatus: Independent applied-research working paper; not peer-reviewed.