The Rail Safety and Standards Board in the UK completed research to identify and describe a set of rail human factors principles that can be applied to the design and operation of rail-specific AI systems. These can help:increase the likelihood that AI systems in rail optimise human performance and decision making and reduce the risk that they deteriorate and impair human performance.The paper describes the principles, how they were developed and how they can be applied to optimise the design, implementation and operation of rail-specific AI systems.