Abstract
In this paper we present a case study about the development and delivery of a mobile application fostering sustainable urban mobility by supporting collaborative behaviours among travellers. This application, called ViaggiaTrento, has been designed based on the requirements expressed by student commuters reflecting on their travelling experience with local transport in the city of Trento, Italy, and has then been fed back to this initial community and subsequently to the rest of citizens. A critical mass of users has been growing since then, with a relevant percentage of citizens downloading and positively rating ViaggiaTrento.