Calculation of quantities in the design of infrastructure structures has been calculated for many years by use of classical formula of the Arithmetic mean between two cross sections multiplied by the length between them. This equation has been synonymous with the accurate calculation of quantities in infrastructure projects. Other equations that have been used, but not so frequently, are the prismoid formula or mid sectional area method.
This paper analyses the accuracy of several equations (formulas) for calculating quantities and compares the results with the volume of 3D modelled terrain on different types of sections, terrain category and type of infrastructure road. 3D modelled terrain is a 3D solid element derived by calculating volume surface. The volume surface is a difference between a base surface and comparison surface which means that Z-value (vertical value) of any given point is the difference between Z-values of the surfaces. In the infrastructure context, volume surface calculates the difference between new top surface or planum surface and existing ground which provide accurate calculation results.
The purpose of this paper is also to examine using volume surface method as an appropriate substitute method for volume calculation.

earthworks; calculations; volume; formula; volume calculation