This paper explores the process of piled foundation design and how it can benefit from the inclusion of previous test data and case histories from nearby or geologically similar sites. The interaction between the soil and the structure is critical to the behaviour of a pile and is a function of both the ground conditions and the method of pile construction. An accurate model of the ground conditions is required for the design, as is a detailed knowledge of the method of pile installation and its subsequent interaction with the soil. Where case histories are available they can be utilised to refine the design or to reduce the risk associated with a solution. This is currently often done in a subjective manner by the application of engineering judgement and personal experience. This paper discusses a quantitative method which can be used to employ data from case histories and provide an objective approach to the inclusion of existing knowledge and experience. Bayesian updating is utilised to improve the model of the ground conditions and subsequently the degree of uncertainty is reduced. The probability of failure has been seen to be reduced by this process, as demonstrated through the application an example situation
