Integrating the normative with the positive dimension of the new science for cities: A geodesign-based framework for Cellular Automata modeling

Cellular Automata (CA) models are powerful simulation tools to study complex urban systems. Although there has been considerable amount of CA-based modeling work reported in the literature, few have been used as actual planning or policy making tools. The goal of this research aims to address the problem of “unapplicable CA models” by combining CA models with the framework of geodesign. Inspired by Batty's new science of cities, we put forward a geodesign-based framework for CA modeling to integrate the positive and normative dimension of the new science of cities as envisioned by Batty. Instead of merely applying CA models to positive urban studies, which typically requires more accurate predictions, we advocate the integration of positive (i.e. urban simulation) and normative (i.e. design) city science via the application of CA modeling to geodesign. By linking CA simulation with the geodesign framework, a geodesign-based CA model is developed and six urban design scenarios are integrated into the model, to test the urban growth impacts of these scenarios and generate a new design scenario accordingly. Using a case study of urban growth in Changping District, Beijing, we demonstrate that the normative and the positive dimension of Batty's new science for cities can be integrated. Geodesign, as a new conceptual framework, is helpful for streamlining the CA modelling process to evaluate different design scenarios and design new scenarios. In return, CA models could also contribute to the geodesign process by offering a tool for simulating and evaluating impacts of different design scenarios on urban growth.