The general urban model: Retrospect and prospect

The general urban model is viewed in brief retrospectively, mainly emphasizing the transition for the monocentric 'classical' elements of such a model to the multicentric. The emphasis of the paper, however, is on future prospects. It is argued that it could be developed as the basis of a model-based 'big picture' of urban development through five layers of disaggregation – from the global to the local. There are many opportunities for submodel development but the main future challenge is the modelling of urban and regional evolution. Progress in modelling urban and regional systems as complex nonlinear systems with particular reference to path dependence and phase transitions is reviewed. The idea of urban and regional 'DNA' is introduced which leads to a 'genetic medicine' view of aspects of planning.