Travellers with visual impairments may face substantial information gaps on their journeys by public transport. For instance, information displayed in trains, as well as on departure boards in train stations and on platforms, are often not available in acoustic or tactile form. Digital technologies, such as smartphones or smartwatches, can provide an alternative means of access. However, these alternatives do not guarantee that the user experience is comparable in value, quality and efficiency. The present case study details a participatory design process, where travellers with visual impairments co-designed a mobile app. The goal was to tackle information gaps on journeys by public transport and to learn how participatory design can facilitate the provision of comparable experiences for users with disabilities. Travellers with visual impairments were involved in a collaborative process in all project phases, including problem identification, technical feasibility, proof of concept, design and development. Participatory design contributed to a thorough understanding of the user perspective and allowed the app to be optimised for the needs of travellers with visual impairments. Furthermore, co-design proved to be an effective method for fostering awareness and knowledge about digital accessibility at all organisational levels.