SIMULACRA: Fast Land-Use—Transportation Models for the Rapid Assessment of Urban Futures

Abstract

We are building a series of fast, visually accessible, cross.-sectional, hence static urban models for large metropolitan areas that will enable us to rapidly test many different scenarios pertaining to both short-term and long-term urban futures. We call this framework SIMULACRA which is a forum for developing many different model variants which can be finely tuned to different problem contexts and future scenarios. The models are multisector, dealing with residential, retail/service, and employment location, are highly disaggregate, and subject to constraints on land availability and transport capacities. They have an explicit urban economic focus around transport costs, incomes, and house prices and thus encapsulate simple market-clearing mechanisms. Here we will briefly outline this class of models, paying particular attention to their structure and the way physical flows and locations are mirrored by economic flows in terms of costs and prices. Several versions of the model now exist, but we will focus, first, on the simplest 'one-window' desktop pilot version with the most obvious graphical interface; and, second, on a much more elaborated framework developed for web access, extensible to web service architectures and other related services. To demonstrate its flexibility and intelligibility, we define the various interfaces and demonstrate how the aggregate model can be calibrated to the wider London region to which it is applied. We will demonstrate the model, albeit briefly with respect to the rapid assessment of different urban futures-"what-if " scenarios, based on the impact of new London airports in the Thames Estuary. The key feature of this entire project is that the model and its variants can be run in a matter of seconds, thus entirely changing the traditional dialogue associated with their use and experimentation.

A Recursive Spatial Equilibrium Model for Planning Large-Scale Urban Change

“…Given the traditional emphasis on land-use and transport planning, the main urban models in policy use since Lowry (1964) are built on spatial interaction models (Batty, 1976;Wilson, 1967). Effective and practical models have been created for assessing property development and transport options at detailed geographic scales through a close integration of the spatial interaction model with random utility theory (McFadden, 1974), national/regional inputoutput tables (Leontief, 1986), land-use and floorspace stock market models (Echenique, 2004;Echenique et al, 1969), transport demand forecasting (Ben-Akiva and Lerman, 1985; Daly and Zachary, 1978;Domencich and McFadden, 1975), road traffic assignment (Sheffi, 1985), GIS and big data analyses (Batty, 2010;Batty et al, 2013). Their strengths lie in the explicit incorporation of planning and infrastructure constraints and the incorporation of policy inputs over explicit time horizons.…”

New roles for urban models: planning for the long term

“…Lowry's land use constraints play an important role. In the Simulacra model, these are handled by a factor which simulates land price (Batty et al, 2013); in the Dearden and Wilson (2015) case, by a measure of housing pressure which can then be used to adjust prices. However, what is interesting in the case of scenario development is the possibility of modifying the constraints, for example, as we have noted, by making some of the land that has been categorized as unusable as available for residential development.…”

Conception and use of an individual-based model of residential choice in a planning decision process. Feedback from an experimental trial in the city of Besançon, France

“…According to Batty et al (2013), the role of models in the planning and design of city systems has radically changed during the last decades. ''Fifty years ago there was a sense in which both model builders and stakeholders regarded models as providing predictions which could be used with some confidence to help figure out the impact of their plans in rather definite ways with a high degree of certainty.…”