TRAM：電気通信関連事故地図法

Telecommunications networks are essential to the functioning of modern society, and large-scale disruptions in these networks can significantly impact societal operations. This paper presents Tram (Telecommunications Related AcciMap), an accident analysis method developed to support the analysis of accidents in telecommunication networks. Tram aimed to allow lessons learned from an accident to be used to mitigate and/or prevent new accidents, ultimately enhancing societal resilience. Initially, we studied the state-of-the-art in accident analysis methods, concluding that we should start from the AcciMap method since this is the most popular and appropriate method for our purposes. Tram has been developed through iterative cycles in which improvements have been proposed and validated; this paper focuses on the last iteration. Tram is a validated method that supports comprehensive analyses of telecom accidents. The latest version added support to the representation and mitigation of positive feedback loops during telecom and information technology systems breakdowns, and can help prioritise the recommendations derived from an analysis. This paper demonstrates that Tram is a suitable method to analyse and learn lessons from accidents in the telecom domain. Particularly, our findings with the application of Tram to real-life accidents indicate that dividing the analysis process by participant expertise can negatively impact the efficiency of the overall process, so the partitioning of the analysis process should be carefully considered.