Pits
This dialog is used to add pits for cost calculation and alignment optimization.
Add (Button)
Add a new pit. You will be prompted for the station.
Remove (Button)
Remove a pit.
List
Display all pits and their station. Select a list item to display and edit properties. Double click to change the station.
Note: pits created with station set to "Start of Alignment" or "End of Alignment" will NOT adjust automatically their station if the alignment changes length.
Borrow/Waste (Radio Buttons)
Define the purpose of the pit. Borrow generates material, Waste, removes it.
Variable volume (smart pit) (Check Box)
When checked, the optimizer will automatically determine the amount of material that needs to be wasted or to be borrowed.
Access station (Edit Box)
Station on the alignment from which the pit is accessed. Note that the access station must lie within the horizontal alignment.
Modify Station (Button)
Allow to modify the station.
Identifier (Edit Box)
Optional identifier for tracking purposes.
Access distance (Edit Box)
Distance from the alignment to the pit, sometimes called deadhaul. Adjust this distance to accommodate pits that lie outside the horizontal station range; for example if a pit is accessed from station 500 but the design alignment starts at 1000, add 500 to the Distance.
Material/Waste quality (Drop List)
The behaviour of this control depends on whether the current pit is defined as Borrow or Waste.
Borrow pit
Choose the extraction Material type defined in your Ground Types table. If you want to extract two materials from the same site, define another pit at the same location.
Waste pit
In this case you can define what materials the pit will accept in two ways:
Use Material (Check Box)
If you set the Use Material check box, then you are prompted for a material defined in your Ground Types table. The pit accepts only the material specified. This is how you might build a stock pile
If you clear the Use Material check box, then then you are prompted to select a minimum Waste quality. Set to Q1 (worst) to accept all materials.
Excavation cost (Edit Box)
Borrow pits only.
Cost to excavate material from the pit. This can differ from the excavation cost defined in the Ground Types table which is used when material is extracted from the road-bed (and not from a pit).
Gnd table value
Displays the excavation cost for this material, defined in the Ground Types table.
Set (button)
Press to update your excavation cost to match the Ground Types table value.
Capacity (Check Box and Edit Box) or Volume (Edit Box)
When Variable volume is set, near the top of the dialog box, you may provide a pit Capacity; to do this, set the Capacity check box and enter a maximum volume in the edit box. If the Capacity check box is clear, then the pit is assumed to have infinite capacity (shows inf in the edit box).
When Variable volume is clear, you you must provide a pit Volume; This exact amount of material will be borrowed or wasted. This can be useful to use up (Borrow) or create (Waste) a stock pile.
Usage (Edit Box)
Actual amount of material that is being wasted or borrowed. This value is only available when the cost is up-to-date.
Volume units for pits
In general units for volumes are defined in your Ground Types table when you set the Expansion Factors for each material in the Design tab; most engineers work in banked units.
If your Waste pit specifies material by Quality and you have entered a finite Volume or Capacity, then the volume is in geometric units. In other words, we don't know what material is to be placed in the pit, so we can't apply the appropriate the Expansion Factors.
Site preparation (Edit Box)
Cost to open the pit: clearing, stripping, etc.
If there are multiple Variable pits to choose from, the optimizer may not open all of them; the Site preparation cost will be considered when minimizing overall cost.
