Safety management systems (SMSs) have gained importance since the 1970s and changed focus from individual management activities to more systematic frameworks. The methods, techniques and tools used in them also became more and more sophisticated. However, from the perspectives of the researcher, company, auditor, government and (safety-specialised) organisation, the modelling of safety management is still in need of improvement. Modelling of safety management means developing a generic model that can cover all SMSs. This generic model (or system) will look into the common constituent parts of an SMS and details of those parts. Theoretical models have been developed extensively, however, quantifying how safety management controls risk is one of the difficulties in applying these models, especially the quantification of safety management deliveries. Therefore, this research aims to develop a quantitative approach to the modelling of safety management. @en

This paper describes safety management systems (SMSs) on five core aspects: definition, evolution, models, purpose and common elements of SMSs. A safety management system implements safety management activities, so an overview of definitions of safety and safety management sheds light on the content of an SMS. SMSs emerged from the risk concept and safety defences. The development of SMSs was boosted by research into ‘safety’, ‘management’ and ‘system’ theories, (safety) risk analysis techniques, safety audit tools, and related standards. Consequently, the study of SMSs became a multidisciplinary topic and through modelling SMSs, a generic framework can be established aiding the effectiveness of SMSs.

There are two main groups of models informing SMSs: (1) accident related models, and (2) organisational models. The relationship between these two models is outlined in this paper. Moreover, we discuss that SMSs studies and models are developed for two main purposes: control and compliance. To control means by implementing safety systems or subsystems, an SMS is able to control risks and to improve continuously, as well as comply with the appropriate standard management systems. As the key to implementing a functional SMS is to carry out common managerial processes, we map the elements of various SMSs to a generic SMS to explore the extent to which they correspond. Like a diamond needs to be cut with facets to show its brilliance, this paper intends to determine and clarify the ‘facets’ of an SMS, and to distinguish all issues clear-cut for the modelling of an SMS.@en

Safety Management Systems usually follow specified formats, as required by standards and other procedures. The quality of such systems is often obtained with assessments at the ordinal measurement level. This paper introduces a barrier-based safety management system coupled with a quantitative approach to safety management modelling. The risk management part of this system is composed of so-called delivery systems, which describe the management processes in place in order to manage barriers. The proposed approach aims to determine how the delivered management factors affect risks by influencing the functioning of barriers. Taking the competence delivery system as an example, competent people are delivered to carry out the tasks of barriers, and these tasks guarantee barriers’ effectiveness. In this research, barriers are grouped into five types. By quantifying competence indicators and the performance of each type of barrier, the link between a delivery system (competence) and barriers is established. Other delivery systems can be quantified in a similar way, meaning that safety management systems will work more efficiently with such monitoring. In addition, this quantification can be used as input for audits, by making assessments more transparent.@en