Error Analysis for Volume Calculations Using Spot Reduced Levels

Abstract

The volume calculation of soil to be excavated is important in construction projects for the cost estimation prior to the construction. Generally, it is carried through the spot heights, using a hypothetical grid drawn across the area to be excavated. The volume enclosed by grid lines is normally calculated by multiplying the average heights of the spots by the area of the grid. The area of a grid is generally selected as three of four. The actual volume varies with the section of unit grid and more over that, with the surface variation which is not reflected by spot heights. The study was carried out to investigate the error in volume calculation due to surface variation. A physical model was developed to generate different surfaces for unique grid with constant spot heights and the error was correlated to middle height to introduce an accuracy index. It was found that the developed physical model provides an acceptable estimation of volume, according to the middle height. The outcome of the research would facilitate the construction professionals, to identify the range of volumes to be excavated, with a higher accuracy.