Adjust the proposed grade plane across the grid to balance cut & fill and minimize import/export
This simulator interactively adjusts a proposed grade plane over an existing undulating ground surface, computing cut and fill volumes in real time to help engineers minimize import and export of material — a core task in site grading, road design, and mass haul optimization.
The simulator divides the site into a 5×5 grid (25 cells) of equal square cells. The existing ground surface is a fixed undulating plane; the proposed grade is a tilted flat plane controlled by base elevation, X-grade, and Y-grade. At each of the 36 grid nodes the cut/fill depth = existing elevation − proposed elevation (positive = cut, negative = fill). Each cell volume is computed as the average of its four corner depths times the cell area, then converted from cubic feet to cubic yards (÷ 27).
A shrink/swell factor accounts for the volumetric change when bank material is stripped, hauled, and compacted. Compacted fill volume requires more bank-cut material because soil densifies: fill volume (bank) = fill volume (compacted) × (1 + shrink%). The net earthwork balance = total cut (bank) − total fill (bank); a balanced site (net ≈ 0 CY) minimizes off-site haul costs.
Mass haul and earthwork methods are covered by FHWA Standard Specifications for Highway Construction and state DOT grading specifications. Proctor compaction testing per ASTM D698 (Standard) or ASTM D1557 (Modified) establishes the reference maximum dry density for compaction control. Typical compaction specifications require 95% of Modified Proctor for structural fills under buildings and pavements, and 90% for embankment fills. Shrink factors are established in geotechnical reports per these standards.
The goal of earthwork balance is to minimize the net haul distance and volume of material imported or exported. The mass haul diagram (cumulative net volume vs. station) identifies where the "balance point" lies along a road alignment. Cut material within the free-haul distance (typically 500–1000 ft per spec) can be reused as fill at no extra cost; material beyond this is overhaul, billed per CY-station.
Shrinkage factors for common materials: sand/gravel 5–12%, silty/sandy soil 10–20%, heavy clay 20–30%, rock (blasted) swells 20–40%. A poorly balanced site can add 15–30% to total earthwork costs through unnecessary borrow or waste haul. Grade tilting (as in this simulator) is a classic technique to shift the cut-fill balance across an undulating surface.
Adjust the proposed base elevation to raise or lower the grade plane and observe the cut/fill map shift from red (cut) to blue (fill). Tilt the plane in X and Y using the grade sliders to match the existing terrain slope and reduce net haul. Increase grid spacing to model larger cell sizes, or adjust the shrink/swell factor to match your geotechnical report. The status banner turns green when the site is within 5 CY of balance.
A mass haul diagram plots cumulative net earthwork volume (cut minus fill, adjusted for shrinkage) against distance along an alignment. A horizontal line intersecting the curve at two points defines a balanced section where cut equals fill within that reach. This tool provides the grid-based volumetrics that feed the mass haul analysis for a site or road project.
A conservative default for silty/sandy soil is 15% shrinkage (enter 15 in the shrink field). For preliminary budgeting, use 10–15% for granular material and 20–25% for clayey soil. Always request a geotechnical report with Proctor test data before finalizing construction quantities on bid documents.
Engineers use design software (Civil 3D, Bentley Civil Designer) to try multiple proposed grade options and view cut/fill maps and mass haul diagrams interactively. Key strategies include adjusting subgrade elevation, changing profile grade points, varying superelevation transitions, and identifying areas where deep cut can be redistributed to nearby fill sections to avoid overhaul.
Bank (in-situ) volume is the soil measured in place before disturbance. Loose volume is the expanded volume after excavation and loading (typically 20–30% larger than bank). Compacted volume is the final volume after placement and compaction, which is typically 10–25% less than bank volume for cohesive soils. Earthwork contracts are typically bid on bank CY.
This grid method is best for site grading. Road earthwork typically uses the average-end-area method computed from cross-sections at regular stations (25–50 ft) along the alignment, with a prismoidal correction applied to improve accuracy in curved or tapered sections. This tool demonstrates the principles; use Civil 3D or similar for production quantities on road projects.