Brussels mobility in 2050: Participatory mixed-method scenario building to explore alternative futures

Mobility is deeply embedded in people’s everyday lives and fundamental in shaping society. Therefore, transport policy needs to be embedded in a well-grounded view of the future, while also being resilient to external shocks. One of the difficulties in ensuring the resilience of transportation systems is the large variety of factors of uncertainty that characterizes the field. Scenario building is one method that can address this issue by exploring alternative futures besides a most likely or desired one. But to increase the likelihood of translating exploratory scenarios into policy making, these should be developed in a participatory manner. One of the difficulties encountered when developing scenarios using quantitative methods is that these methods are often a black box for participants, while qualitative methods on their own can lack legitimacy. Mixed-method approaches can therefore be an interesting avenue for research to facilitate participation in transport scenario building, by providing a mathematical structuring of the scenarios, enriched with qualitative stakeholder input. In this paper, we explore how participation can be facilitated in mixed-method scenario building. We further elaborate on the combination of a systems dynamic-approach (cross-impact balance analysis) with creative workshops by testing three approaches to facilitate participation: a Delphi survey, personas, and the use of visual harvesting. We develop four scenarios for the future of urban mobility in Brussels, Belgium, by 2050, and report on the lessons learnt. We find that the use of Delphi as a stakeholder engagement method too rapidly closes down the scenario funnel when used for selecting factors of uncertainty. The use of personas allows for the development of engaging narratives, and could be helpful for the involvement of people less familiar with participatory exercises. Lastly, the use of visuals throughout the workshops was found to stimulate active discussion and resulted in a more transparent scenario development process, by increasing traceability