Experiments in Urban Modelling for County Structure Planning: The Area 8 Pilot Model

This paper presents the form of the pilot model designed for the Reading–Wokingham–Aldershot–Basingstoke Subregional Study, known as Area 8. The model is based on the well-developed structure first used by Lowry, but in the quest to make the model operational, significant improvements have been made to the use of locational constraints, the treatment of external zones, and calibration. The original model is first outlined, and then a number of algorithms designed to speed up the application of the constraints are tested, the best one reducing the overall model running time by 60%. External zones are considered in the context of constraints, and a much accelerated calibration technique based on a combination of Newton–Raphson and direct-search methods is introduced. The calibration of the model in Area 8 is described, and the problem of measuring and interpreting locational attraction is also addressed. Finally the implications of using the model in county structure planning are traced, in preparation for the application of the large-scale model which is under construction.