Both land use and transportation are part of a dynamic system that is subject to external
influences. Each component of the system is constantly evolving due to changes in
technology, policy, economics, demographics and even culture/values, among others.
As a result, the interactions between land use and transportation are played out as the
result of the many decisions made by residents, businesses and governments. The field of
urban dynamics has expanded the scope of conventional land use models, which tended
to be descriptive, by trying to consider the many relationships behind the evolution of the
urban spatial structure. This has led to a complex modeling framework including a wide
variety of components. Among the concepts supporting urban dynamics representations
are retroactions, where as one component influences others. The changes will influence
the initial component as feedback, either positively or negatively. The most significant
components of urban dynamics are: