A subdivision is designed to balance. The bill of quantities shows cut to fill, a modest topsoil strip and no import. The contractor prices it, wins it, and four months later has bought several thousand tonnes of fill and paid to remove a similar volume of material that would not compact.
Nothing unusual happened. The design balanced in geometry and the job did not balance in material, which is a different question and one the bill of quantities does not answer. Understanding the difference — and pricing it — is among the highest-value analyses available to a civil estimator, and it takes about an hour.
The quantity in the bill is not the quantity you move
A designer computes cut and fill volumes from surfaces. Those numbers are geometrically correct and they describe voids in the ground, not truckloads. Between the two sit five effects, and each of them moves the number in a direction the bill does not show.
- Bulking. Material excavated occupies more volume loose than it did in the ground.
- Compaction shrinkage. Placed and compacted, it usually occupies less than it did in the ground.
- Suitability. Some of what you cut cannot lawfully or technically go into fill.
- Moisture. Material too wet or too dry will not compact until it is conditioned, and conditioning takes time, space and sometimes additives.
- Losses. Topsoil strip, spillage, trimming waste, over-excavation and material used for temporary works and haul roads.
The general estimating method is covered in our guide to preparing civil works cost estimates, and the trade-specific content in our guide to writing a winning tender for earthworks projects. This guide takes one item out of both and treats it properly, because it is the item that most often decides whether an earthworks job made money.
Bank, loose and compacted
Three states, three different volumes for the same material, and confusing them is the commonest arithmetic error in earthworks pricing.
| Measure | What it describes | Where it is used |
|---|---|---|
| Bank (in situ) | Material as it sits undisturbed in the ground | Design volumes, bill of quantities, survey comparisons, and usually the measurement basis for payment |
| Loose | Material after excavation, in the bucket, on the truck or in a stockpile | Truck capacity, cartage cycles, stockpile space |
| Compacted | Material placed in the fill and compacted to specification | Fill volumes, layer counts, conformance testing |
The three questions that follow, and they should be asked on every earthworks job:
- Which measure is the schedule item paid in? A rate per cubic metre means nothing until you know whether it is bank, loose or compacted measure. Get it from the method of measurement, not from assumption.
- Which measure did you build your production rates in? Truck cycles are loose. Excavator production is usually quoted bank. Compaction production is compacted. Mixing them silently is how a rate ends up wrong by a wide margin.
- Which measure is the survey comparison in? Progressive quantity measurement from surfaces gives bank or compacted, never loose.
Bulking and shrinkage
Bulking is the volume increase from excavation, caused by the material breaking up and taking in air. Shrinkage is the volume reduction when that material is placed and compacted, often to a density greater than it had in the ground. Because both are commercial assumptions applied to a measured surface, the surfaces themselves have to be right — see our guide to drone survey and reality capture.
Both vary enormously by material type and condition — a dense clay, a loose sand, a weathered rock and a blasted rock behave nothing alike, and the same material behaves differently wet and dry. This guide states no factors, because a factor used on the wrong material produces a confident and badly wrong number. The factors that matter are the ones for your material, and the reliable sources are the geotechnical report, the testing done for the project, and your own measured records from similar ground.
What matters more than the exact figures is understanding the direction and where it bites:
- Bulking drives cartage. Truck movements are set by loose volume. A cartage estimate built on bank volume will understate the number of loads.
- Shrinkage drives the balance. Where compacted fill occupies less than the cut it came from, you need more cut than fill to balance — and a design that balanced on geometry will leave you short.
- Rock is the extreme case. Excavated rock bulks heavily and, unless it is processed, makes poor general fill. A cut in rock and a fill requiring select material are two different jobs that happen to be adjacent.
- The two effects do not cancel. They act at different stages on different volumes, and treating them as offsetting is a common shortcut that produces the wrong answer.
Where you have machine control and progressive surface capture, you can measure your own bulking and shrinkage on a live job and build a set of factors for the ground you actually work in — one of the more valuable by-products of the technology described in our guide to machine control and GNSS.
Why the balance almost never balances
Bringing it together, here is why a job designed to balance usually does not.
| Effect | Direction | Consequence |
|---|---|---|
| Compaction shrinkage | Reduces usable fill from a given cut | Short of fill |
| Topsoil strip | Removes the upper layer from the cut volume, and it is rarely fill material | Short of fill, plus a stockpile to store |
| Unsuitable material | Removes part of the cut from the fill pool entirely | Short of fill and long on spoil |
| Select fill zones | Some fill must be better material than the site produces | Import required even when the total balances |
| Subgrade replacement | Soft spots excavated and replaced beyond the design volumes | Extra cut, extra spoil, extra import |
| Moisture | Wet material cannot be placed until dried | Delay, or reclassification as unsuitable if there is no time |
| Trimming and losses | Over-excavation, spillage, haul road consumption | Small individually, real in aggregate |
Note that five of the seven push the same way: short of fill and long on spoil. That is the characteristic failure of an earthworks estimate, and it is expensive in a specific way — you are buying material to bring in at the same time as paying to take material away.
Unsuitable material: the item that decides the job
More earthworks money is won and lost on this single item than on production rates.
Material can be unsuitable for fill for several distinct reasons, and they have different consequences:
- Technically unsuitable — organics, topsoil, highly plastic clay, oversize rock, material outside the specified plasticity or grading limits. Cannot go into fill as specified, may sometimes be used in landscaping or non-structural zones.
- Too wet or too dry — suitable material in an unsuitable condition. Recoverable with time and treatment, which the programme may or may not allow.
- Contaminated — a different regime entirely, with classification, tracking and licensed disposal. Covered in our guide to landfill, remediation and contaminated land civil works.
- Acid sulfate soils — requiring treatment and validation before disposal or reuse, common on coastal and floodplain ground.
Three commercial questions decide what this costs you, and all three should be answered before the bid goes in:
- Who decides what is unsuitable, and against what criteria? A specification with defined test criteria is manageable. One where the superintendent decides on inspection is a commercial risk, because the volume is then somebody else’s judgement.
- Is there a provisional quantity, and what happens beyond it? Unsuitable material is frequently a provisional item — see our guide to bills of quantities, provisional quantities and PC sums — and the treatment of quantities above the allowance is the clause that matters.
- Where does it go, and at what rate? Disposal cost depends on classification, on levies in your jurisdiction and on the receiving facility. Assuming a clean-fill rate for material that turns out to need a licensed facility is a large and common error.
Where the material encountered differs materially from what the site information indicated, there may be an entitlement under the latent conditions provisions — but that depends on the contract, the information provided and prompt notice. Our guide to latent conditions in civil contracts covers what a site information clause does and does not give you.
Reading a mass haul diagram
A mass haul diagram is treated as a big-project technique. It is not — the arithmetic behind it works on a subdivision or a two-kilometre road job and can be sketched on a page.
The idea is simple. Along the alignment, accumulate cut as positive and fill as negative, plotting the running total. The resulting curve tells you things a cut-and-fill table cannot:
- Where the balance points are — the chainages at which accumulated cut equals accumulated fill, meaning material can move between them without import or export.
- Which direction material should move, which determines haul road layout and sequencing.
- How far it has to travel, which is the number that drives cost.
- Where you are genuinely short or genuinely long, and therefore where import or disposal is unavoidable rather than a planning failure.
- Whether a small design change would help — raising or lowering a grade slightly can shift a balance point substantially, which is a legitimate alternative to propose.
Two practical refinements matter. Apply your bulking and shrinkage factors before plotting, so the curve reflects material rather than geometry — a curve built on design volumes will show a balance that does not exist. And overlay the unsuitable material: a section of cut that cannot be used as fill is not available to the curve, however favourably it sits.
The output is a haul plan, and a haul plan is what turns an earthworks methodology from description into evidence. Our guide to writing a construction methodology statement covers the presentation.
Free haul, overhaul and how haul is actually paid
Some contracts pay for moving material as part of the excavation rate; some pay separately once it travels beyond a stated distance. The terminology is old and still in use.
- Free haul — a distance within which haulage is deemed included in the excavation rate.
- Overhaul — haulage beyond that distance, paid separately, usually per unit volume per unit distance.
- All-in — a single rate covering excavation, haul and placement wherever it goes on site. Simple, and it puts all the haul risk on the contractor.
Establish which structure applies before pricing, because the same job prices very differently under each. Under an all-in rate, a job that turns out to need material moved from one end of the site to the other absorbs that cost entirely; under an overhaul arrangement, the extra distance is measured and paid. Where the contract is all-in and the haul distances are uncertain, that uncertainty is priced risk and belongs in the rate or in a qualification.
Two further points on haul that are easy to underestimate. Haul cost is driven by cycle time, not distance — a short haul up a steep grade on a wet surface can cost more per cubic metre than a longer one on a formed road. And truck movements bring heavy vehicle obligations that fall on you as loader, scheduler and consignor, covered in our guide to chain of responsibility for civil contractors. Mass limits are also a haul constraint: a truck that cannot legally carry a full measure of a dense material carries fewer cubic metres per load than the arithmetic assumes.
Import, spoil and the double purchase
The financial shape of an unbalanced job is worth setting out plainly, because it is what makes balance worth working on.
| Cost | Applies to |
|---|---|
| Purchase of imported material | Every cubic metre short |
| Cartage in | Every cubic metre short, over the distance to the source |
| Placement and compaction | Every cubic metre, whether won on site or bought |
| Loading and cartage out | Every cubic metre long, over the distance to the receiving site |
| Disposal fee and levy | Every cubic metre long, at the rate for its classification |
| Double handling | Anything stockpiled and moved again |
A cubic metre that could have stayed on site and been used avoids items one, two, four and five. That is why balance work has such a high return: each unit of imbalance removed cancels a purchase and a disposal simultaneously. It is also, incidentally, the largest carbon reduction available on most civil jobs — the alignment described in our guide to embodied carbon and decarbonisation.
Two practical routes worth investigating before accepting an imbalance. Off-site placement: a neighbouring development, a farmer wanting fill or a council project may take clean material at a fraction of disposal cost, and sometimes for nothing — but check the receiving site’s approvals, because placing fill on land can itself require authorisation, as our guide to environmental approvals and permits sets out. And local sourcing: the difference between a quarry at twelve kilometres and one at forty is usually larger than any rate negotiation, which is covered in our guide to materials supply agreements and quarry supply.
Treating site-won material instead of buying new
Where material fails the specification but is not contaminated, treatment is the option that converts spoil back into fill and removes both sides of the double purchase. Where import is unavoidable and recurring, some contractors look at owning a pit, which is a larger decision than it appears.
- Moisture conditioning — drying by spreading and turning, or adding water. Cheap in equipment, expensive in time and space, and entirely weather-dependent.
- Lime or cement stabilisation — modifying plasticity or adding strength so material meets the specification, and the same process used to build pavement layers, as covered in our guide to pavement stabilisation, testing and conformance. Established, effective on many clays, and requiring mix design, testing and specialist plant.
- Screening or crushing — removing oversize, or processing rock into usable material.
- Blending — combining two site materials, or a site material with a smaller quantity of imported product, to meet a grading.
The comparison to make is total cost against total cost: treatment plus testing plus time, against purchase plus cartage in plus cartage out plus disposal. Treatment frequently wins by a wide margin and is not considered because the specification did not suggest it. Where the specification does not permit it, proposing it is a legitimate alternative — our guide to non-conforming and alternative tenders covers how to offer one without making your bid non-conforming.
Two cautions. Treated material needs its own testing regime and conformance records, which belong in the inspection and test plan described in our guide to quality management plans and ITPs. And stabilisation is weather-sensitive and has a working window after mixing — a wet week can waste both the additive and the material.
Stockpiles, double handling and space
Every cubic metre placed in a stockpile is handled at least twice, and stockpiling is usually a symptom of a sequencing problem rather than a plan.
- Space is the binding constraint on constrained sites, and stockpile volume is loose measure, not bank — a distinction that has embarrassed a lot of site layouts.
- Segregate by material. Topsoil, general fill, select fill and unsuitable material mixed in one stockpile is one stockpile of unsuitable material.
- Stockpiles degrade. They take up water, they lose it, and they get contaminated by what is placed near them.
- They are an environmental control item — sediment control, dust, and sometimes a location approval. Covered in our guide to construction environmental management plans.
- They surcharge excavations. A stockpile near the top of a batter or a trench is a load on it, as our guide to temporary works and excavation support explains.
- Off-site stockpile sites need approval and usually a lease, and both take longer than people expect.
The design principle is to move material once wherever possible: cut directly to fill in the same operation, sequenced so the fill area is ready when the cut is available. Achieving that is a programming exercise, and it is where the mass haul curve and the programme meet — see our guide to writing a construction programme for tenders.
Moisture, weather and the clay problem
On clay sites, moisture is not a factor in the earthworks. It is the earthworks.
Compaction requires material within a moisture range relative to its optimum. Outside that range it will not achieve density regardless of how many roller passes it receives, and continuing to work it usually makes it worse. The practical consequences for pricing and programming:
- Wet clay cannot simply be placed. It must be dried, treated or removed, and drying needs dry weather, spreading area and time.
- Production rates are seasonal on these sites in a way they are not on sand or rock. A rate measured in summer does not apply in winter.
- Rain stops the job for longer than it rains. The site has to dry before work resumes, and the ratio is not one to one.
- The programme should carry weather allowance explicitly, and where the contract provides for extensions of time for inclement weather, the notice and record-keeping requirements have to be met — see our guide to extension of time and delay claims.
- Protect the surface. Sealing off with a roller before rain and shedding water rather than ponding it is the difference between resuming in two days and re-excavating a layer.
The commercial structure that fits
Given how much of this is genuinely unknown at tender, the contract structure matters more on earthworks than on almost any other trade.
| Structure | Who carries quantity risk | When it is appropriate |
|---|---|---|
| Schedule of rates, remeasured | The principal | Where quantities are genuinely uncertain — most earthworks. See schedule of rates vs lump sum |
| Lump sum on design quantities | You, entirely | Only where the ground is well understood and the design is final |
| Provisional quantities for unsuitable material | Shared, up to the allowance | Common and workable — provided the treatment above the allowance is clear |
| Separate import and disposal items | The principal, at your rates | The most contractor-friendly structure, and worth requesting |
Where the structure is lump sum and the ground is uncertain, the assumptions you priced on should be written into the tender as qualifications — the balance assumed, the unsuitable volume allowed, the moisture condition assumed, the haul distances assumed, and the disposal classification assumed. That converts a silent risk into a stated one, and if the qualification is rejected you at least know before signing.
During delivery, this is the trade where measurement discipline pays most directly. Progressive surface capture gives you quantities monthly rather than at the end, which supports both the claim and the forecast in our guide to job costing and cost control — and an earthworks job that is drifting out of balance shows up in that data months before it shows up in the bank.
What to put in the tender
Most earthworks methodologies describe plant and sequence. A response that includes the balance analysis is doing something competitors are not.
- State the balance position. Whether the job balances on your analysis, and if not, by how much and in which direction.
- Show the haul strategy. Direction of movement, balance points, haul road layout, and why the sequence follows from it.
- Name your assumptions. Bulking and shrinkage basis, unsuitable material allowance, moisture condition, disposal classification and destination.
- Explain what happens if the material differs. The contingency — treatment, alternative source, alternative disposal — demonstrates you have thought past the base case.
- Quantify the benefit where you are proposing something. “Balancing on site removes an estimated four hundred truck movements” is concrete, checkable, and reads as both commercial and environmental competence.
- Tie it to the programme, so the sequence and the weather allowance are visibly consistent with the haul plan.
Checklist
- Do you know which measure — bank, loose or compacted — each schedule item is paid in?
- Are your production rates and your quantities in the same measure?
- Have you applied bulking and shrinkage factors appropriate to this material, from the geotechnical report or your own records?
- Have you recomputed the balance in material terms rather than accepting the design’s geometric balance?
- Have you deducted topsoil, unsuitable material and select fill zones from the available fill pool?
- Do you know who decides what is unsuitable, and against what criteria?
- Is unsuitable material a provisional quantity, and what happens above the allowance?
- Have you confirmed the disposal classification and a receiving facility that will take it, at a quoted rate?
- Have you plotted a mass haul curve using material volumes, not design volumes?
- Does the contract use free haul and overhaul, or an all-in rate?
- Are haul costs based on cycle time rather than distance alone?
- Have mass limits been checked for the material density, so loads are legal and the load count is right?
- Have you investigated off-site placement and confirmed the receiving site is approved to take it?
- Have you compared treating site-won material against importing and disposing?
- Is stockpile space sufficient in loose measure, and are materials segregated?
- Are stockpiles clear of batter and trench edges?
- Does the programme carry a realistic weather allowance for this material and season?
- Are your balance, unsuitable and haul assumptions written into the tender as qualifications?
- Will you measure quantities progressively during delivery rather than at the end?
The short version
- Design volumes describe geometry. The quantity you move is a different number, and the bill does not contain it.
- Bank, loose and compacted are three different volumes for the same material. Know which one every rate and every production figure is in.
- Bulking drives cartage; shrinkage drives the balance. They act at different stages and do not cancel out.
- Five of the seven common effects push the same way — short of fill and long on spoil — which is the characteristic earthworks estimating failure.
- Unsuitable material decides more earthworks jobs than production rates do. Find out who determines it, against what criteria, and what happens above any provisional allowance.
- A mass haul curve works on a subdivision, not just a motorway — but plot it on material volumes, not design volumes, or it shows a balance that does not exist.
- Establish whether haul is free haul and overhaul or an all-in rate before pricing. The same job prices very differently.
- Every cubic metre of imbalance is bought twice — imported and disposed. Removing it cancels both, which is why balance work has such a high return.
- Treating site-won material often beats importing plus disposing, and is usually not considered because the specification did not suggest it.
- On clay, moisture is not a factor in the earthworks — it is the earthworks. Rain stops the job for longer than it rains.
- Earthworks is the trade where a remeasured schedule of rates most clearly belongs. On lump sum, write your assumptions in as qualifications.
- Put the balance analysis in the tender. Most competitors describe plant and sequence; almost none show the material.
Sources and further reading
This guide is general information for Australian civil construction businesses and is not engineering, geotechnical or legal advice. Bulking and shrinkage behaviour, compaction moisture ranges, material suitability criteria and stabilisation mix design are material-specific and site-specific engineering matters — no factor, percentage, moisture range or suitability threshold is stated in this guide and none should be inferred. Use the values determined for your project by a qualified geotechnical engineer and the testing required by the specification. Waste classification, disposal routes, levies and approvals for placing fill on land are set by the environmental regulator in each jurisdiction and differ. Methods of measurement, haul payment structures and provisional quantity provisions are set by the contract. Always work from the geotechnical report, the project specification, the executed contract and current professional advice.
- Standard earthworks practice and terminology in Australian civil construction — bank, loose and compacted measure, bulking and shrinkage, free haul and overhaul, and the mass haul diagram — described in §02, §03 and §06. These are established industry conventions; the numerical factors that apply to any particular material are determined by geotechnical investigation and testing for that project and are deliberately not stated here.
- Project specifications and methods of measurement governing material suitability criteria, compaction requirements, moisture limits, select fill zones and the basis on which excavation and haul are measured and paid, referenced in §02, §05, §07 and §12. These are set per project and are the authority for every quantity question in this guide.
- State and territory waste classification frameworks, disposal levies and approvals for receiving fill on land, referenced in §05 and §08. Classification determines lawful disposal routes and cost, and differs between jurisdictions. Sourced in full in our guides to landfill, remediation and contaminated land civil works and environmental approvals and permits.
- Related TenderBuilt guides carrying the primary-source detail referenced above: writing a winning tender for earthworks projects, preparing civil works cost estimates, latent conditions, bills of quantities and provisional quantities, schedule of rates vs lump sum, materials supply agreements and quarry supply, chain of responsibility, machine control and GNSS, job costing and cost control and embodied carbon and decarbonisation.