From Macro to Micro—How Much Micro is too Much?

Abstract

This paper discusses the usefulness of the trend towards microsimulation in urban transport and land‐use modelling for the planning practice. It starts with a history of urban transport and land‐use models and observes a trend towards increasing conceptual, spatial and temporal resolution stimulated by improved data availability, higher computer speed and better theories about mobility and location of individual behaviour. While recognizing these advances, the paper calls attention to the problems of disaggregate models in terms of data requirements, computing time and stochastic variation and shows that in the light of new challenges cities are facing environmental problems, such as energy scarcity and climate change, not further refinement but more focus on basic needs and constraints is needed to make the models useful for the planning practice. As a possible solution to the macro–micro debate, it calls for a theory of multi‐level models according to which for each planning task there is an appropriate level of conceptual, spatial and temporal resolution. The paper closes with an example of a multi‐level land use, transport and environment model ranging from the European to the grid cell level.