The way in which computers are used is important in the theory, philosophy and practice of architecture. Architects are already using computers to construct complex three dimensional geometric models of their buildings and are beginning to analyse these models using environmental and structural software, a development which raises new questions about the role of architects and engineers. This dissertation puts forward the hypothesis that architects will at times need to be actively involved in computer programming by writing or modifying software. The hypothesis is based on the assumption that the form of a building and its spatial configuration are influenced by the nature of the design process itself. If architects are to have a complete and subtle control over design and to identify their own personal aesthetic language, they must also have control over the design process including the way computer software tools are developed and used. The hypothesis is tested using the example of a ferry terminal, a building type whose function is largely dominated by passenger circulation. Even thought passengers have a very straightforward aim to reach their final destination, the rules governing the way passengers move around the building are complex and a single computer program will not be able to cover all possible aspects of such behaviour. Thus, architects must have the freedom to formulate different rules and study the effects they have on their design. This particularly applies in non-emergency situations when each individual moves inside the building according to different needs and desires. A program was written which runs in real time so that the architect can see the effect of changing the parameters that control the process. The program can be used as evaluation mechanism to study the performance of postulated design or it can be use as creative mechanism where the design may emerge out of the process in the same way that animals create paths in the woods. Either way, the general aim is to optimize the design according to criteria over which the architect, again, must have complete control.