The gestalt in the machine : ensuring usability through more holistic iterative rail simulator design processes

The end user of a rail simulator experiences the gestalt, meaning that all of the parts add up holistically to form an overall impression. Similarly, a holistic and dynamic process of iterative design in the developmental cycle of a rail simulator is crucial to the integrity of this impression, meeting the needs of the end-user, and assuring its usability for the target audience. However, fully understanding the fidelity requirements is difficult if the requisite collaboration between the procurers and developer is underspecified. Once full-cab simulators have been deployed, any options for improvement may be limited, costly, and physically constrained by poorly informed choices during the early design stages. This paper presents the case study of a full-cab replica Q-class rail simulator that was designed for systematic human factors and occupational safety research. Once the simulator was deployed, a fidelity audit revealed a number of design issues that limited the options for improvement, particularly with the restricted field of view in the track vision and limited functionality of the “bail-off” braking system. These could be traced back to deficiencies in the developer-procurer dynamic during its original iterative design process, specifically through a disaggregated view of its purpose, and nuanced differences in collaborative principles and practices. Whilst a number of the identified problems were eventually resolved, some of the larger concerns could not be addressed as easily. However, plans to relocate the simulator to a new location provided the opportunity to revisit the design and address the issues. This paper describes the Engineers perspective of how the previously unresolvable issues were addressed, and presents the methods that were used to collaborate during the iterative process in order to produce a positive outcome. These outcomes may be used to innovate simulation design and delivery, inform asset modification and improve systems assurance. Some of the original design choices went on to foreshadow what could and could not be improved in spite of the relocation, and the paper concludes with a commentary of the importance of professional and holistic collaboration when specifying a simulator.