Represent free haul and overhaul volumes using grade point and balance point methods.
During project development, contractors and design engineers may try to balance the mass haul requirements by considering free haul distances, any overhaul , and the use of borrow pits for embankments and dump sites for extra excavated volumes, based on the economic haul limits and the site conditions.
In Autodesk Civil 3D, you can specify the free haul distance as required. You can also specify the location of borrow pits and dump sites along the roadway, with assumed capacity of the borrow pits or dump sites.
There are two ways of representing free haul (and any overhaul) in mass haul diagrams in Autodesk Civil 3D:
- measured from grade points
- measured from balance points
Grade Point Method
The arrows indicate free haul distance. The number (1) indicates grade points. Freehaul volume is indicated in green (and by the grid between the green areas and the balance line) and overhaul volume is indicated in red.
From grade points, a segment the length of the free haul distance, which is parallel to the balance line, is dropped so that the ends of the segment just touch the mass haul line . The area enclosed within the segment and the mass haul line represents the free haul volume. Further, perpendicular lines from the ends of the segment are dropped so that they touch the balance line. The areas enclosed within these lines, the balance line, and the mass haul line represent the overhaul volume.
Balance Point Method
The arrows indicate free haul distance. The number (1) indicates balance points. Freehaul volume is indicated in green and overhaul volume is indicated in red.
In a mass haul diagram, the balance points are located on the balance line, where the net volume is zero. In the balance points method of measuring free haul, the mass haul line is duplicated and shifted horizontally to the right (where the project transitions from cut to fill) or to the left (where the project transitions from fill to cut) by the free haul distance. The area enclosed by the two mass haul lines on the left if above the balance line, or on the right if below the balance line, represents the free haul volume. The remaining intersecting area represents the overhaul.