This paper is concerned with how management and organisational influences can be factored into risk assessments. A case study from the rail transportation sector illustrates how organisational factors can act as high level influences which are manifest as operational errors giving rise to major accidents. A model is proposed which describes the interrelationships between management influences, immediate causes and operational errors. This model can be used for organisational auditing, monitoring and system design. A strategy is described for collecting data from an existing organisation to develop a specific form of the generic model. The final issue addressed is the use of the model to quantify the effects of organisational influences on risk arising from human error. A numerical case study is provided to illustrate the approach.