Expansion and compaction is critical for calculating mass haul and estimating end haul. Although the concept is very simple, expansion and compaction can be confusing.
When defining ground types you are asked to supply expansion factors associated with the materials. These factors change the way in which volumes and areas are reported in the mass haul and data windows. The most common uses of these factors is to report volumes in one of the following systems:
a) Bank Cubic Meters (Cubic Yards)
In this system, cut and fill volumes are reported as the equivalent volumes they would occupy in their natural state (in the bank or in situ).
b) Loose Cubic Meters (Cubic Yards)
In this system, cut and fill volumes are reported as the equivalent volumes they would occupy in a loose state (i.e. piled in a truck).
c) Final Cubic Meters (Cubic Yards)
In this system, cut and fill volumes are reported in the state as they would occur in the final road bed (compacted).
There are two changes in material density that take place during road building. The first is an expansion that occurs when material is excavated. The second transition occurs when excavated material is placed back into the road bed and compacted as fill.
In LOCATION, volumes are calculated directly from the cross sectional areas of cut and fill. The cut volume is then multiplied by the Cut Expansion Factor (as set in the Ground Types dialog) before it is reported in the Data Window. Similarly the fill volume is multiplied by the Fill Expansion Factor (as set in the Ground Types dialog) before it is reported in the Data Window
Example
Suppose when material is excavated it expands by a factor of 1.2 and that when this loose material is placed back into the roadbed it compacts by .8.
The following factors will result in volumes in the three reporting systems. The factors (Cut Factor and Fill Factor) are the numbers which would be entered in the Ground Type Editor dialog.
