Cut/fill settings control how Level AI and Cut/Fill calculations compare the existing ground surface against the proposed design surface.
These settings affect earthworks quantities, balancing behaviour, and the interpretation of cut/fill results. They should be reviewed before running Level AI, especially where topsoil stripping, unsuitable material, bulking, or surface offsets are required.
When these settings are used
Cut/fill settings are used when:
Running Level AI earthworks optimisation
Reviewing cut/fill balance
Generating cut/fill overlays
Comparing existing and proposed surfaces
Accounting for topsoil, bulking, unsuitable material, or surface adjustments
The earthworks extent still controls where Level AI is allowed to modify the ground. Cut/fill settings control how quantities are calculated and adjusted within the model.
Key concept: existing surface vs proposed surface
Cut/fill is calculated by comparing:
the existing surface, usually survey, LiDAR, or existing ground; and
the proposed surface, created by Level AI.
Where the proposed surface is above the existing surface, the result is generally fill.
Where the proposed surface is below the existing surface, the result is generally cut.
Additional settings can then adjust these quantities to account for stripping, surface offsets, bulking, and unusable material.
Settings (web)
Setting | What it means | Typical use |
Existing topsoil depth | Depth of topsoil stripped from the existing ground before cut/fill quantities are calculated. Applied when the existing cut/fill surface is set to Building, Pavement and Grass Subgrade. It is not applied when the existing surface is set to Existing Ground Surface. | Use when topsoil must be removed before bulk earthworks. |
Proposed topsoil depth | Depth of topsoil allowed for the final proposed surface. Applied when the proposed cut/fill surface is set to Building, Pavement and Grass Subgrade or Building FFL, Pavement and Grass Subgrade. It is not applied when the proposed surface is set to Finished Surface. | Use when the final surface includes a topsoil layer above subgrade. |
Existing cutfill surface adjustment | Vertical adjustment applied to the existing surface before cut/fill comparison. See below for more info. | Use when the existing surface needs a correction or allowance before quantities are calculated. |
Proposed cutfill surface adjustment | Vertical adjustment applied to the proposed surface before cut/fill comparison. See below for more info. | Use when the proposed design surface needs to be compared at a different construction level, such as subgrade. |
Bulking factor (%) | Percentage increase applied to cut material when considering how much volume it occupies after excavation. | Use when cut material expands after excavation. |
Surface adjustment settings
Surface adjustment settings control which vertical level is used when calculating cut/fill quantities.
For the existing surface, users can choose either the raw Existing Ground Surface or an adjusted Building, Pavement and Grass Subgrade level.
For the proposed surface, users can compare against Building, Pavement and Grass Subgrade, Building FFL, Pavement and Grass Subgrade, or the final Finished Surface.
By default, both existing and proposed cut/fill calculations use Building, Pavement and Grass Subgrade, meaning quantities are generally calculated to the earthworks/subgrade level rather than directly from existing ground to finished design surface.
The Civil 3d sub assemblies are used for the subbase calcs (can be applied on impervious areas too). For buildings, the subbase default settings can be configured. Topsoil is determined from settings.
Bulking Factor
Bulking factor accounts for the increase in volume when material is excavated.
For example, a bulking factor of 15% means that 1.00 m³ of in-situ cut material becomes approximately 1.15 m³ after excavation.
This affects how cut material is compared against fill requirements.
Use bulking factor when excavated material expands after being cut and moved.
Example
If the model calculates:
cut: 10,000 m³
fill required: 10,000 m³
bulking factor: 15%
Then the available bulked cut volume may be considered approximately:
10,000 × 1.15 = 11,500 m³
This does not necessarily mean the site is balanced. Unsuitable material, compaction, topsoil, import/export, and staging assumptions may also affect the final balance.