Hydrogen is increasingly recognized as a component of sustainable energy systems as it offers a pathway to decarbonize various sectors. Its transport by rail can fill a gap between high-capacity pipeline-based transportation and low-capacity flexible road-based transportation but poses safety risks to the railway system and its surroundings. While storage solutions have reached a high level of technical maturity, the catastrophic consequences of a hydrogen tank explosion, i.e., the rare worst case, can include loss of life and infrastructure damage, underscoring the urgency of developing strategies to minimize exposure to these risks. The overall objective of this research is the development of an approach driven by open geodata that estimates the societal and monetary risk of compressed gaseous hydrogen transport by rail, specifically of rupture events of transported hydrogen tanks. It provides a geospatial workflow that estimates societal risk, as well as damages to railway infrastructure elements and the built environment in the hazard areas around potential tank rupture sites. Based on this, a penalty-based optimization approach is proposed to identify risk-minimizing hydrogen supply routes in the German rail network. Case studies demonstrate the effectiveness of the developed methodology to find safer routes for hydrogen transport and point out the role of tank design and routing decisions on risk mitigation. The methodology can be adapted to other dangerous goods and contributes to the ongoing development of resilient transportation systems.