Contractors management functions : an integrated approach for planning, estimating and control

Planning, estimating and control management functions as performed by Portuguese construction companies were studied. For this purpose, inquiries were made into the way a set of Portuguese contractors carried out these tasks, with special reference to planning, estimating and the preparation of data for control during the pre-contract stage. There is a lack of integration among those functions in the current practice of companies surveyed. This is a problem that companies would like to see solved. Data systems analysis was used to tackle the problem. It was concluded that there is no functional dependency between planning and estimating in most construction projects. This is especially due to the form in which. data is structured in the basic documents currently used for those functions (the bill of quantities for estimating and the construction programme for planning). A possible integrated approach to planning and estimating is suggested by considering construction works assigned both to the items of the bill of quantities and to the activities of the construction programme. This facilitates the preparation of data for control on site because costs and time are closely related in this approach. A model for the integration of planning and estimating management functions during the pre-contract stage of construction projects is presented. The model also enables one to achieve efficient preparation of data for control on site. Computer support for the model is also presented. This is based on a Database Management System which provides for an adequate environment for the model. The model was tested in some Portuguese construction companies, and led to satisfactory results. Those companies highlighted the advantage of building up the model upon a relational database which makes data manipulation and retrieval easier and allows for integration among management functions.