Maintenance-related incidents and accidents : aspects of hazard identification
Sammanfattning: The satisfaction of stakeholders depends upon the fulfilment of their requirements. Two important stakeholder requirements related to technical systems are dependability and safety. However, system operation will gradually impair its performance leading to potentially hazardous states of the system. Maintenance is all activities aimed at retaining a system in, or restoring it to, a state where it can fulfil the stakeholders’ requirements. However, although maintenance is performed in order to ensure dependability and safety, incorrectly performed maintenance may contribute to accidents with extensive losses. Traditionally, human failures have often been appointed as one major cause of these maintenance-related accidents. However, human failures are not completely satisfactory as an explanation for incidents and accidents since there most often are other contributory causes to these failures. The purpose of this thesis is to explore and describe hazards contributory to maintenance-related incidents and accidents, in order to support continuous risk reduction. To fulfil the stated purpose, two case studies, supported by a literature study, have been performed. One case study focused on documented maintenance-related incidents and accidents within the Swedish railway. The second case study focused on perceived hazards in relation to maintenance execution within the Swedish paper industry. The railway case study indicates that improper infrastructure maintenance is a major cause of collisions and derailments within the Swedish railway. Furthermore, the study indicates that the three major maintenance-related hazards within the Swedish railway system are: communication errors, information retrieval errors and omitted operations. The study also proposes that it is not good enough to accept human failures, i.e. human error or rule violation, as a root cause of maintenance-related incidents and accidents. Both case studies show that a major maintenance-related hazard is insufficient communication between different activities associated with maintenance execution. Another common finding from the studies is that incidents manifested during maintenance execution might be caused by hazards in other maintenance-related activities within the maintenance process. In addition, both case studies show that a proposed process model of maintenance is a valuable support in hazard identification.
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