Can the Theory of Situated Situation Awareness be applied in the context of rail signalling?

Automation and digitalization have been increasing in the work environment and tasks of rail signallers in Germany. This has a significant impact on rail signaller situation awareness. In electronic interlockings with a high level of automation, the main task of rail signallers nowadays is monitoring the functioning of the automatic train control. However, maintaining good situation awareness continuously while carrying out a mainly monotonous monitoring task can pose difficulties for operators. Regarding the importance of situation awareness for carrying out the task of rail signalling, it is necessary to analyse rail signaller situation awareness with regard to increased automation. In previous studies, rail signaller situation awareness was assessed using variations of the Situation Awareness Assessment Technique (SAGAT). Results showed that performance was not predicted by the results of the SAGAT. Instead, rail signallers achieved a good performance accompanied by mediocre results in the SAGAT. It was hypothesised that the good performance was due to mental models and tacit knowledge, subsumed as implicit situation awareness. In the present study, the theory of situated situation awareness is applied as an alternative to implicit situation awareness. According to the theory of situated situation awareness, not all information necessary for an operators’ situation awareness is stored directly in working memory (internal storage). Instead, it is assumed that some information is stored externally in an operators work environment, while operators store the location of the information in the work environment in working memory as part of situation awareness. Because the theory of situated situation awareness considers external as well as internal information storage, hypotheses about information in both storages can be derived and tested. Thus, a more comprehensive understanding of rail signaller situation awareness can be accomplished. The current study aims to predict if rail signallers store specific information elements internally or externally. This prediction is verified using data from a study conducted in a high fidelity simulation of an electronic interlocking. Eleven rail signallers took part in the study. Situation awareness was assessed three times for each participant using SAGAT. In addition, participants were asked where in their work environment they would find the necessary information to answer each query. By using this method of assessing situation awareness it is possible to identify which information is stored internally (correct response), externally (correct location) or not at all (incorrect response and location). The result of this study will offer further insight into what comprises rail signaller situation awareness. Thus, a better assessment of rail signaller situation awareness will be possible, as queries can be tailored to the expected place of information storage. Furthermore, the additional knowledge about rail signaller situation awareness can be used to improve rail signallers’ work environments to better support the development of good situation awareness