### Abstract:

Volume calculation of earth work of road
pavements is very important section in project cost
estimation. Practically it is very difficult to calculate the
actual volume of a pavement as the cross section varies by
its width, height, shape and formation level. The
conventional calculation method is to use end area rule
which calculates the area between two consecutive
sections as the product of average area of sections and
distance between sections assuming there is a linear
variation of sectional area between two sections. The
actual volume of the section deviates from the calculated
volume using end area rule due to the violations of
assumptions of the equation. This study was carried out to
investigate on the errors of application of end area rule in
volume calculations of highway pavements. The actual
volume was calculated by a numerical analysis by
integration and also by preparing a model using computer
software. A modification factor was developed using the
perpendicular distance between the centroids of cross
sections and end area rule was applied with this
modification factor. The validity of the results is evaluated
by comparing the calculated volume with actual volumes
obtained by mathematical and software models. It was
concluded that a volume can be calculated up to a better
accuracy using this modification factor together with the
end area rule.