Conceptual Cost Estimate of Road Construction Projects in Saudi Arabia

This study aims at developing regression models to predict the total construction cost of a road project in the early phases. The models were developed based on 52 sets of data collected in Saudi Arabia. The projects were implemented during 2011. The procedure used resulted in the formulation of 5 regression models; 2 of them include bid quantities of the major construction activities as independent variables and 3 include road length and road width as independent variables. The coefficient of determination (r2) of the developed models is ranging from 0.65 to 0.97. This indicates that the relationship between the dependent and independent variables of the developed models is good and the predicted values from a forecast model fit with the real-life data. The value of the Mean Absolute Percentage Error (MAPE) of the developed regression models is tested. It is ranging from 17% to 42%. The results compare favorably with past researches which have shown that the estimate accuracy in the early stages of a project is between ±25% and ±50%. Such types of models are very useful, especially in simplicity and ability to be handled by calculator or using a simple computer program. It has a good benefit in estimating project cost at early stages of the project, since the information needed could be extracted easily from sketches or scope definition of the projects.