Ubiquitous software applications can be more responsive if they can adapt to their surrounding situation without relying on users' continuous commitment. In dynamic environments such as public transit settings, where information is rapidly changing and passengers' demography are not uniform, an adaptive mobile application to navigate passengers based on their profile and context may be a good example of an emerging self-adaptive and context-aware mobile application. In this paper we demonstrated the use of an open source framework to develop a travel assistant application to help passengers with special needs in public transit environments.