Thursday, January 12, 2017

Transportation in Agent-Based Urban Modelling

Sarah Wise, Mike Batty and myself have recently had a chapter published in Agent Based Modelling of Urban Systems entitled "Transportation in Agent-Based Urban Modelling". In the chapter we provide a critique in how transportation has been included or omitted from agent-based models and suggest how it might be handled in future applications.

Our argument is that transportation plays an important role in nearly every aspect of our daily lives. However, within agent-based models that explore urban problems, transportation is often omitted. Using representative case studies (e.g. from crime, disease spread, and land use) we present different levels/tiers of complexity at which transportation systems are captured with agent-based models (as shown in Table 1). Table 2 shows how these tiers of complexity are captured within crime models.  For interested readers, below you can see the abstract to our chapter.  

As the urban population rapidly increases to the point where most of us will be living in cities by the end of this century, the need to better understand urban areas grows ever more urgent. Urban simulation modelling as a field has developed in response to this need, utilizing developing technologies to explore the complex inter-dependencies, feedback's, and heterogeneities which characterize and drive processes that link the functions of urban areas to their form. As these models grow more nuanced and powerful, it is important to consider the role of transportation within them. Transportation joins, divides, and structures urban areas, providing a functional definition of the geometry and the economic costs that determine urban processes accordingly. However, it has proved challenging to factor transportation into agent-based models (ABM); past approaches to such modelling have struggled to incorporate information about accessibility, demographics, or time costs in a significant way. ABM have not yet embraced alternative traditions such as that in land use transportation modelling that build on spatial interaction in terms of transport directly, nor have these alternate approaches been disaggregated to the level at which populations are represented as relatively autonomous agents. Where disaggregation of aggregate transport has taken place, it has led to econometric models of individual choice or microsimulaton models of household activity patterns which only superficially embody the key principles of ABM. But the explosion in the availability of movement data in recent years, combined with improvements in modelling technology, is easing this process dramatically. In particular, agent-based modelling as a methodology has grown ever more promising and is now capable of emulating the interplay of urban systems and transportation. Here, we explore the importance of this approach, review how transportation has been factored into or omitted from agent-based models of urban areas, and suggest how it might be handled in future applications. Our approach is to take snapshots of different applications and use these to illustrate how transportation is handled in such models.

Keywords: Agent-based modelling; urban systems; urban modelling

Full Reference:
Wise, S. Crooks, A.T. and Batty, M. (2017). Transportation in Agent-Based Urban Modelling, in Namazi-Rad, M., Padgham, L., Perez, P., Nagel, K. and Bazzan, A. (eds), Agent Based Modelling of Urban Systems, Springer, New York, NY, pp. 129-148. (pdf)

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