Design costing models: An application of heuristic substitution

A KBS for the preliminary costing of bridges is described. This system is based on the principle of heuristic substitution and provides the designer with a quick and easy way of obtaining a preliminary costing for a bridge design. The system can then be used to explore the implications of varying this design and allows easy comparison with alternative designs. By doing this, the system successfully fills a gap in the costing mechanisms currently used in practice. Preliminary trials with the system show that the speed and ease of use of the software enables designers to search for optimal solutions. It is thought that systems of this type will have a substantial impact on present conceptual design practices.