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S. Sillem

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7 records found

Previous exposure to yellow:number aspects as a cause for SPAD incidents

When a train passes a red aspect, this is called a Signal Passed at Danger event or SPAD. Sometimes it is easy to identify the SPAD cause but in other cases it is unclear why the incident occurred, especially if the system operated as usual and the train driver was trained and experienced just like his or her colleagues. In previous research, train driver deceleration behaviour has been shown to be influenced by frequent exposure in the previous 14 days to less restrictive and visually similar signal aspects in the same location. Previous exposure can contribute to SPAD causation unless the initial insufficient deceleration is corrected in time. Six years of SPAD data and red aspect approaches in the Netherlands was used to test whether previous exposure to yellow:number aspects corresponds with a statistically significant increase in SPAD incidents if there is a small window for correction available to drivers. The permitted track speed and signal distance influence the size of this window. The results provide evidence for previous exposure as a cause for SPADs and details to identify locations with increased SPAD probability. Changes in infrastructure and timetable design or adding safety measures for these locations can prevent future SPADs. ...
Journal article (2022) - Leonie Boskeljon-Horst, Simone Sillem, Sydney W.A. Dekker
There is little empirical evidence on the predictive value of safety culture assessments (SCAs) in relation to how accident-prone an organisation might be. Recently, Antonsen not just demonstrated how a quantitative SCA mispredicted future safety outcomes, but actually showed an inverse relationship between the assessment and subsequent critical incident investigation findings. To add to our understanding, this article presents research on whether a SCA has a predictive capacity for safety outcomes. Like in Antonsen's research, an opportunity emerged when a helicopter taxiing accident, resulting in a rotor strike occurred for a helicopter squadron that had just undergone a SCA. The assessment used ‘culture ladder’ rubrics for its findings, which allowed us to look for specific features in the subsequent independent accident investigation (in which the researchers were not involved). As with Antonsen's findings, our research shows that a ‘ladder’-based assessment has little predictive value. Any predictive value it has is in the inverse of the assessment findings. For instance, where the SCA showed that the safety culture was very mature regarding finding a balance between safety and the mission at hand or the breaking of rules, the accident investigation pointed these out as the causes of the accident. ...
Journal article (2022) - Leonie Boskeljon-Horst, Robert J. de Boer, S. Sillem, Sidney W. A. Dekker
In this study we identify the differences in goal realisation when applying two conflicting paradigms regarding rule perception and management. We gathered more than 30 scenarios where goal conflicts were apparent in a military operational unit. We found that operators repetitively utilized certain routines in executing their tasks in an effort to realize several conflicting goals. These routines were not originally intended nor designed into the rules and not explicitly included in documentation. They were not necessarily at odds with the literal wording and/or the intent of rules and regulations, although we did find examples of this. Our data showed that local ingenuity was created innovatively within the frame of existing rules or kept invisible to those outside the unit. The routines were introduced and passed on informally, and we found no evidence of testing for the introduction of new risks, no migration into the knowledge base of the organisation, and no dissemination as new best practices. An explanation for this phenomenon was found in the fact that the military organisation was applying a top-down, classical, rational approach to rules. In contrast, the routines were generated by adopting a constructivist view of rules as dynamic, local, situated constructions with operators as experts. The results of this study suggest that organisations are more effective in solving goal conflicts and creating transparency on local ingenuity if they adopt a constructivist paradigm instead of, or together with, a classical paradigm. ...

How incidental learning influences train driver behavior and safety margins (a big data analysis)

Employee behavior plays an important role in the occurrence and prevention of incidents, affecting safety margins. In this study, we examine the potential impact of incidental learning on human behavior in the presence of variation in task design. Incidental learning is the day-to-day on-the-job learning that occurs unintentionally. This learning influences which behavior (schema) is more likely to be activated in the employee’s brain. We posit that an incorrect schema can be activated and lead to undesired behavior if the employee is often exposed to (visually) similar tasks that require different behavior. In rail transport, there is a risk of trains passing through red signals. The train driver’s behavior plays an important role in preventing these signal passed at danger (SPAD) incidents. In this study we used speed and location data to analyze train driver deceleration behavior during red signal approaches in the Netherlands. The Dutch rail system showed variation in yellow signal aspects and signal distance. An analysis using 19 months of empirical data indicated changes in behavior when the employee had been previously exposed to different behavior requirements in the same location with a similar yellow signal. These results imply that task design can be improved by taking into consideration what an employee is exposed to during other moments of the shift, and not just during the execution of the specific task. ...
Journal article (2019) - Julia Burggraaf, Jop Groeneweg, Simone Sillem, Pieter Van Gelder
The field of safety and incident prevention is becoming more and more data based. Data can help support decision making for a more productive and safer work environment, but only if the data can be, is and should be trusted. Especially with the advance of more data collection of varying quality, checking and judging the data is an increasingly complex task. Within such tasks, cognitive biases are likely to occur, causing analysists to overestimate the quality of the data and safety experts to base their decisions on data of insufficient quality. Cognitive biases describe generic error tendencies of persons, that arise because people tend to automatically rely on their fast information processing and decision making, rather than their slow, more effortful system. This article describes five biases that were identified in the verification of a safety indicator related to train driving. Suggestions are also given on how to formalize the verification process. If decision makers want correct conclusions, safety experts need good quality data. To make sure insufficient quality data is not used for decision making, a solid verification process needs to be put in place that matches the strengths and limits of human cognition. ...
Journal article (2018) - Paul Swuste, Simone Sillem
Objective This article discusses the rise of European postgraduate courses in safety science and the content and quality of the Management of Safety Health and Environment (MoSHE) course of Delft University of Technology. Materials and methods Literature search, document analysis, interviews. Results The different MoSHE years show a varied picture of this post academic program. In the Netherlands the course is unique with a central focus on risk management and sustainability, supported by scientific developments in the areas of safety, health, environment, organizational science and psychology. In all year-groups the quality of the course was assessed with a short questionnaire, collecting opinions of course members on individual presentations and the course as a whole. Quality of the course was regularly discussed through the contacts of the course coordinator with module leaders, and at meetings of course committees, and leading to changes in content of modules. After MoSHE 1 (1989), 14 (2008), and 17 (2012) the courses’ structure, organization and content was changed radically. Only, the quality system of the course remained implicit. Using the model of the European Foundation for Quality Management a first set-up for a quality system is presented. Over the years the academic nature of the program has changed substantially. This is one of the challenges for the future to find a balance between the domains taught and between an academic approach and practical skills. The course could benefit from a greater input of process safety and safety in high-tech-high-hazard sectors. ...
Doctoral thesis (2010) - S Sillem, Ben Ale