기획 및 타당성조사 단계의 국도건설 공사비 추정 모형

Abstract

An exact estimating about construction cost in the beginning phase for a project enables to support making a decision for the project propulsion and to compare other alternatives. Besides, this estimation allows establishing an effective budget by offering information about the construction cost from now on. It is very difficult to exactly estimate construction cost because of weakness for available information at the planning phase. However, because of its features of road project, important decision making for a certain project – the direction for the project, a choice for the optimal route, selection for the location of interchange – is mostly decided at the planning phase. Currently, even though Ministry of Land Infrastructure and Transport(MOLIT), Korea Development Institute(KDI), and etc. have already suggested possible models for estimating construction cost, these models are still kept in a simple way with construction cost per the length of the standard. Besides, there is no guideline to estimating cost for the project so it is believe that there has to be a proper guideline for it. The main purpose of this study is to overcome the limitation of estimating model for exist construction cost and to develop practical model which can measure possible cost of the feasibility phase and, systematic and very accurate planning phase of highway construction, which use obtainable data and the factors of construction cost in its phase of feasibility study. There are results from this study. 1) Through the literature review, related to an estimating model for possible construction cost on the road construction of the inside and outside of the country, the components of construction cost on the planning phase with rare information have shown that it is more proper to use an area of the road surface (earthwork, bridge, tunnel). 2) Regression model about estimating construction cost based on possible construction cost (an area of the road surface:㎡) was developed in the planning phase then measuring efficiency of construction cost on a design was calcualated. The result showed lower measuring efficiency level with its figure -15.80%～21.30% than that of the previous study and it is shown that this figure is placed within the range -30%～+50% based on the model of the planning phase, which AACE suggest. It is believe that using this model would help ordering agency and business developer to recognize reasonable cost estimation in the planning phase. 3) The model of possible construction cost in the feasibility phase which analyzed the collected material on existing construction cost drew a model based on a form of matrix which indicated quantity and the unit cost depending on the components of construction cost. The model of feasibility phase suggested in this research can well reflects its features of each project as standard work of safety facility, Especially depending on quantity, it makes possible to calculate its available cost on safety facility and auxillary which is estimated by percentage of other work. As a result of it, the accuracy of its estimating construction cost would be improved. 4) In this study, measuring efficiency indicating figure -13.70%～17.90% on the model of matrix (quantity × unit cost) depending on the quantity in the feasibility phase is in the lower level than the previous study. In addition, it shows that the figure is within the range -20%～+30% of its lay out model suggested by AACE. It is possible to predict more accurate construction cost than that of previous one through using this model and it can contribute to the improvement in living environment for local residents and in the image of construction industry. Moreover, because the model of feasibility phase is the one based on quantity by outline design, its applicability would be more efficient using in reviewing a detailed route of basic design.