Paper: Designing a Sustainable Mobility System for Shared Transportation Antti Jylhä, Laura Haverinen, Samuli Kaipiainen, Giulio Jacucci Department of Computer Science, P.O. Box 68 FI-00014 University of Helsinki, Finland Paula Forbes, Judith Masthoff, Simon Wells Computing Science University of Aberdeen AB24 3UE Aberdeen, UK Jason Finnegan, Luigi Telesca eXrade s.r.l. Via alla Cascata 56/D 38123 Povo-Trento, Italy ABSTRACT Mobile digital devices can help foster more sustainable ur- ban transport behaviours by providing useful and usable tools that support urban travellers when planning and ex- ecuting their trips and enabling new and disruptive travel behaviours. Such digital tools can help travellers to organise shared journeys, such as taxi sharing and car-pooling which are low-emission alternatives to private car journeys. In this paper we report on the participatory design of such a system to support sustainable urban travel. Categories and Subject Descriptors H.5.2 [Information interfaces and presentation (e.g., HCI)]: User Interfaces - User-centered design General Terms Theory Keywords Sustainability; intelligent transport systems; social networks; participatory design 1. INTRODUCTION We report on the participatory design of an urban mobil- ity system that includes mobile digital clients for planning and executing journeys using shared taxis and car-pooling schemes. This is in the context of a wider urban mobil- ity platform called SUPERHUB [7, 1] that aims to provide an integrated, multi-modal system which supports transport needs and encourages environmentally sustainable choices to help limit the environmental impact of transport in modern European urban environments. Based on the findings from the participatory design process, we have had to balance the need for privacy and security, with the sometimes conflicting needs of functionality, ease of use, versatility, and intuitive user experience. Digital technologies are helping to scaf- fold huge transformational impact in modern society. One area in which these technologies are effecting real, disruptive change is in transport, particularly personal, urban mobil- ity. This is especially so where personal urban mobility and mobile digital devices meet. Modern urban mobility is be- ing transformed by the advent of sensor rich, mobile digital devices that are technologically capable, always connected, and relatively cheap. Technology is helping huge numbers of people to travel more quickly, and more efficiently than ever before. Yet it is this very issue of large-scale urban mobility that is a problem. Travelling effectively and effi- ciently in a modern urban environment can be a complex undertaking, something that modern digital devices can be help manage. Our system will propose a shared ride between travelers, whose needs for transportation (such as traveling time and destination) are similar. Ride offers are clustered and a back-end negotiator takes care of matching similar journeys. For the design of such a system for shared trans- port, we argue that it is crucial to involve the potential end- users in the design process as early as possible in order to map out and accommodate the user requirements and ensure that the system contains relevant functionality. Adopting a user centered approach has already provided valuable insight into SUPERHUB users for the design of the persuasive tech- nology aspects of the platform [8, 9]. As a result we have chosen to follow a participatory design approach through- out the project ensuring that users are at the center of our process. 2. BACKGROUND & MOTIVATION The widespread use of smartphones and custom applications has driven the growth of a number of new taxi sharing, car- pooling and other innovative transport solutions. For exam- ple in Helsinki, the open journey planner API [3] offered by the local transport authority HSL has been applied to con- struct numerous mobile applications for planning journeys on public transport. Some new services are aiming to chal- lenge directly the taxi market [4], and [5], while other ser- vices are aiming to simplify car-pooling (e.g., GreenRiders [2]), with little or no payment involved. Previous research on taxi sharing and car pooling systems have investigated for example efficient match-making algorithms [11] indicated that these systems can boost the use of taxi services [6], and proposed a framework based on positioning the mobile ter-