The robustness of human-driven urban systems
The city is a human-driven self-organizing structure.
Most modern models of urban development ignore this obvious property, and
substitute humans with the derivatives of their activity: infrastructure
elements. In infrastructure-based models human population is considered as
the fast component of the system, which adapt to slower infrastructure changes.
Despite noteworthy achievements, the infrastructure-based
view of urban systems is limited conceptually. A more “proper urban model”,
for example one that simulates urban sprawl, is necessarily a multi-agent
one, where decisions to resettle or leave on the one hand or to develop,
destroy, renovate or change the land use on the other, are made by interacting
agents of different (but not many) types: householders, development and commercial
companies, local councils, municipalities. In this way, the achievements
of cognitive, behavioral and social sciences are directly incorporated into
the urban model. Furthermore, multi-agent models can serve as verification
tools for infrastructure-based models, and can be used to establish the limits
of their application.
To elaborate the human-based approach, we present a model
of the urban dynamics that includes agents of two types, householders and
dwelling developers, and investigate the evolution of a simulated urban system,
based upon different assumptions of agents’ behavior. The model clearly demonstrates
that spatial gradients of dwelling prices, self-organizing at the initial
stages of urban evolution, are very robust; their changes demand strong and
extended intervention at above-agent levels. General implications of this
result for the urban dynamics theory are considered. Model results are compared
with data on Tel Aviv land-use dynamics over the last fifty years.
A spectrum of urban multi-agent models, all including
agents of two or more different kinds, is presented, and urban phenomena
that could be investigated with these models are discussed.
Itzhak Benenson
University Tel Aviv
Department of Geography and Human Environment
http://eslab.tau.ac.il
bennya@post.tau.ac.il
Erez Hatna
University Tel Aviv
Environment Simulation Laboratory, Porter School of Environmental Studies
http://eslab.tau.ac.il
erezh51@post.tau.ac.il