Abstract
Since their introduction, self-service ticket vending machines (TVMs) have become an increasingly important distribution channel in the public transport sector, progressively replacing the traditional ticket counter. In a public transport setting, where ticket counter closures have left different groups of people dependent on TVM to meet their mobility needs, a single, effective system is required. Research questions: (1) Which barriers do currently hinder the usage of TVM? (2) Which requirements should a barrier-free TVM fulfill? (3) How can we design a new self-service TVM for a nationwide public railway company? (4) How can we ensure that the usability and user experience (UX) is high for all users, especially for those with low levels of technological affinity? Situating the case: Most other studies on the use and usability of TVMs were conducted as post-hoc evaluations. In contrast, our case study presents a user-centered design (UCD) approach that takes the needs of the different target groups into account throughout the whole development process. Theories and concepts that guided the case included UCD, which involves alternating test and evaluation loops that actively involve users to create a usable product and UX, which describes the quality of the experience a person has when interacting with a specific computer system using a specific interaction technique. Methodology: More than 250 participants were involved in focus groups, observations, interviews, and experiments from the very first stages of development. Interface designs were presented to the future end users to obtain their feedback, with the results fed back into the design process. About the case: A prototype for a novel generation of TVM was developed in three phases: First, the context of use was analyzed. In the second phase, we conducted a requirements analysis. Third, different hardware and software interaction designs were iteratively tested and evaluated. The resulting prototype met the requirements of most user groups, though further adjustments are necessary. Conclusions: The UCD approach proved to be a valuable framework for the development and design of self-service systems.