Abstract
For various participants of projects, accuracy in the estimation of project duration is vital at various stages of the building production process. The importance of the problem has been acknowledged by the industry worldwide, and various models have been proposed in the literature, but all have their limitations. This paper presents a performance-based duration-estimation model that utilizes historical knowledge, in particular information to estimate the worst, best and likely variances of current projects by using the unified structure of an information system developed for design/build organizations. The model allows the estimators to make use of data on past projects. Proposed organizational pattern, design/build, are vital for accessing the as-built schedules and variance information provided by construction groups in a design/build organizational pattern. Our final solution includes an integrated relational database model developed for design/build organizations that provides the integration of satellite software packages, thus eliminating additional efforts for obtaining the data needed in the estimation process.