Computer aider cost modelling at briefng stagelinked to smm

Abstract

Involvement of the cost advisers -in the early stage of the building design process (briefing stage) for the forecasting of probable cost of projects is often minimal. The traditional pre tender estimating techniques such as unit method, cost per unit floor area method, cube method, approximate quantities method and the like used to forecast the probable cost of projects are not satisfactory. This bars the cost adviser to make the fullest contribution in the early design stage decisions. The surveys conducted in this research revealed the fact that local design practice with respect to design stage estimating is limited to unit method, cost per unit floor area method and later stage approximate quantities method and elemental cost method. The use of computer facility to automate tasks in local practice is very low. Quantity surveyors in design offices use spreadsheet software for calculations. Use of database software or other programming languages in the process of cost advice was not evidenced. This research is, thus, aimed at establishing a computer aided cost model based on bill of approximate quantities properly linked to Standard Method of Measurement (SMM) with the flexibility in application during briefing, sketch plan and working drawing stages. Being linked to SMM, the proposed model ensures transformation of design and cost data into a BOQ prepared in accordance with SMM. The current practice of using bill of approximate quantities for cost forecasting is limited to later stages of the design process since the method requires design information to work upon. This difficulty has been overcome in the proposed model by incorporating design and cost data libraries with computer manipulation. .. A case study was used to generate quantities, compile historical design data, and provide causal relationships to the model. These data coupled with solution neutral design information were used to develop design data library and cost data library of the model which provide sufficient information to make professional judgements at the briefing stage.