ABSTRACT
The scale of technological change and its social impacts tends to lead modellers into situations where, having learned to deal with spatial interactions and arrangements, they are suddenly confronted with the need for non-spatial models, or for mixed ones. This consideration highlights the influence on urban growth and form of many technological changes which are affecting employment, health and health care, reproduction and population dynamics, communications, and indeed every aspect of urban life. These changes also suggest that we look for new integrative mechanisms as they exist in urban affairs and as they ought to reappear in urban models. Scenarios which deal in an arbitrary way with the external or exogenous circumstances surrounding a modelling and planning effort are designed to reduce the scope of that effort and thus to make it more effective. Clearly under all of these circumstances, decisions about the uses of technology are political decisions in both good and bad senses.
