Small Changes leAd to Large Effects: Changing Energy Costs in Transport and Location Policy is exploring the relationship between residential location and travel choice at the level of cities. It is undertaken jointly between the UCL Centre for Transport Studies and CASA. The project will benefit from CASA’s land use transport modelling efforts such as the one for the ARCADIA project within SIMULACRA and the previous LUT for London as part of the Tyndall Centre for Climate Change Cities project.

Transport and residential location consume substantial quantities of energy whilst serving only to facilitate primary economic and societal activities. The relationship between urban form and travel patterns is inherently complex: it can be influenced by policy but through many individual personal responses rather than being subject to explicit control. Managing the energy used in transport is therefore an indirect process that works by influencing the amount and distance of travel, the means by which travel takes place, and the energy requirement of the resulting travel. Achieving this effectively requires a full understanding of the many complex interacting social processes that generate the demand for travel and impinge on the ways in which it is satisfied in terms of its supply.

The complexity sciences provide a framework for organising this understanding. In this project, we argue that changes in energy costs generate surprising and unanticipated effects (such as the news from the figure on the right) in complex systems such as cities, largely because of the many order effects that are generated when changes in movement and the energy utilities used to sustain locations generate multiplier effects that are hard to trace and even harder to contain. For example, as energy costs increase, people eventually reach a threshold beyond which they cannot sustain their existing travel patterns or even their locations and then rapid shifts occur in their behaviour. When energy costs reduce, these shifts are by no means symmetrical as people switch out of one activity into another, by changing location as well as mode.

The methodologies we will employ to explore these models involve nonlinearities that are caused by positive feedback effects in complex systems where n’th order multiplier effects are endemic. We will use phase space representations to visualise such changes and then implement these in the operational land use transport model which we will disseminate to our partners in the quest to pose significant policy questions. We believe that we can demonstrate the essential logic of complexity science to a much wider constituency in developing insights into these most topical questions of the changing cost of energy.

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