Railway accidents and incidents: Complex socio-technical system accident modelling comes of age

Abstract

In early 2009 the Contributing Factors Framework (CFF), a manual providing a data set for the coding of systemic factors contributing to rail safety occurrences, was developed and introduced nationally to the rail industry in Australia. This research was interested in using the CFF to model the previously unseen non-linear network interactions and relationships as a more complex systems oriented way of understanding accident taxonomy.To obtain the data necessary for this accident modelling to occur, major rail safety occurrence reports were analysed for the 5 year period 2006 to 2010 using the CFF tool. The contributing factors for four sub-types of major rail safety occurrences were then modelled, including Collisions, Derailments, Safe Working Breaches, and Signals Passed at Danger.The outcome of this project was the development of a new methodology for accident modelling called the Safety and Failure Event Network (SAFE-Net). The SAFE-Net method generates an accident model for each of the various types of railway safety occurrences under investigation. This is in keeping with recent calls for modern day accident models to truly represent the interconnected complex socio-technical systems in which they occur and allows the actual contribution of each factor to be calculated and understood.Safety occurrence contributing factors can now be understood as a network of interacting factors, and safety improvements can be made by focusing on the critical co-occurrence of these various factors. The SAFE-Net method provides an original means of understanding the complexity of the interrelatedness of system factors in rail safety occurrences.