Backcasting city dialogues: Feasible paths of interventions – the case of Vienna

The impact of connected and automated transport systems (CATS) in several areas also has strong implications on a very central question of urban development: Given a certain vision based on a set of quantified policy goals for a city or a region, which supporting role take recommended policy interventions related to CATS to achieve that vision? This article provides a short overview of the backcasting approach applied in LEVITATE that addresses this question.

From a cities’ perspective the advent of connected and automated vehicles (CAVs) is not a strategic goal by itself. Rather, they are welcome if they are able to contribute to the defined smart city goals and have to support a livable city. Improvements in road safety or reductions in the demand for public parking space are promising candidates for such supported goals, with quantitative investigation of impacts currently ongoing in the project. But there are some other impact areas where an increasing market penetration of CAVs (without specific regulations) might be in conflict with the strategic goals of a city: empty AVs avoiding parking fees might increase congestion; the attractiveness of AVs might lead to adverse changes in modal split; acceptance of longer driving distances (due to increased comfort and use of travel time for working) might further increase road traffic and promote urban sprawl. It is therefore essential for cities to integrate the full spectrum of related policy interventions into their considerations to prepare for the era of CATS – right from the start. Some positive impacts might be reinforced and accelerated by the appropriate policies, other desired impacts might occur only if a specific combination of policy interventions is applied – with the appropriate timing – and finally, some unwanted negative impacts might be mitigated by corresponding interventions. These causal relationships, however, are not always as simple and intuitive as it might appear at first sight. A lot of interdependencies – as in every complex system extending over different domains – makes it a necessity to apply a formal approach and consider a set of different methodologies that can support cities in their strategic decisions.

Defining a desirable vision in a quantitative way is the essential starting point for the backcasting process. From that vision the idea is to work backwards, via influencing factors (that are impacting the goals and indicators of the vision), to policy interventions which address these factors and thereby contribute towards the vision. Generating this series of logical links is a central part of the process, as it highlights feasible paths of interventions, steering into the desired direction. The steps in this process are explained in more detail and exemplified for the City of Vienna in the following article by the Austrian Institute of Technology.