Collaborative backcasting for transport policy scenario building

Scenarios are often used to examine different futures where there is considerable uncertainty or where the business-as-usual is no longer appropriate. Backcasting is one form of scenario building where a normative view is taken about desirable futures, and the method then investigates different policy packages that can be used to reach those futures and the alternative pathways that can be followed. Where most difficulties have arisen in the past has been in bridging the conceptual elegance of the approach with the practicalities of implementation. Collaborative backcasting bridges this 'implementation gap' through a participatory approach in which different stakeholders take an active role in building scenarios, in identifying policy measures and packages, and in evaluating different pathways. Using the region of Andalusia (Spain), this paper brings together the different strands of this collaborative methodology where a set of alternative transport futures have been considered, together with the means to achieve a sustainable transport system for 2050. It discusses eight issues: (i) the selection of participants; (ii) the combination of participatory techniques; (iii) the development of learning processes; (iv) the need for and role of mediators; (v) the diversity of transport futures and integration of policy pathways; (vi) the timeline and future horizons; (vii) the acceptability of different pathways; and (viii) the legal and institutional constraints to effective implementation. Conclusions on the appropriateness of collaborative backcasting are drawn.