Earthwork Quantities for Progress Payments, Survey to Survey
A progress payment for earthworks is only as good as the quantity behind it. The contractor claims a volume for the month, the client's engineer checks it, and both need to arrive at the same number from the same surveys. This guide walks through what that quantity rests on — the baseline survey, the volume between two dated surveys, in-place versus loose volume, the work that should not be paid — and what belongs in the file that goes with the payment.
What the payment needs from the survey
Under a unit-price contract the payment for earthworks is a quantity multiplied by a rate: cubic metres of excavation or fill, measured for the period and priced from the bill of quantities. The rate is fixed by the contract; the quantity is what gets argued about. A quantity that holds up has three properties: it comes from surveys both sides accept, it is computed by a method agreed in advance, and anyone can recompute it from the evidence attached.
That makes the survey the backbone of every payment. Each period needs a dated survey of the work area on the same coordinate system and vertical datum as the one before, so that the difference between two surfaces is the work done and not a change of reference.
The baseline: measure the ground before anything moves
Every earthwork quantity is a difference, and a difference needs a starting point. The baseline (original ground) survey is taken before work starts and agreed by both parties; without it the first payment cannot be measured and every later one inherits the doubt.
Keep the baseline as its own dated surface. In STREAM each survey is a terrain scenario with its own date, so the baseline, the period surveys and the design surface sit side by side in one project.
Volume between two surveys: surfaces or cross-sections
There are two accepted ways to compute a period's volume. The surface method subtracts the previous survey from the current one cell by cell over the work area and sums cut and fill separately. The cross-section method cuts sections at a fixed interval along an alignment, measures the cut and fill area at each station and multiplies by the distance between stations. The surface method uses all the measured ground; cross-sections are what many contracts and road specifications still ask for.
STREAM runs both on the same data: cut and fill between two scenarios with the volumes kept separate and a heat map of where they occurred, and cross-sections at an interval you set with a station-by-station schedule (CSV or Excel) and the section drawings as DXF. Run both on the same surveys and the gap between them is itself a useful check.
In-place volume, bulking and tonnes
Excavation is usually paid in in-place (bank) volume — the volume the material occupied in the ground — because that is what a survey of the excavation measures. Loose volume after digging is larger by the bulking factor, and compacted fill can be smaller; mixing the three is a common source of disputes. Say on the quantity which one it is.
In STREAM the bulking factor is an input you enter, never an assumption, and with an in-place density on the project the production is also given in tonnes.
What should not be paid: over-excavation and work outside the design
Not every cubic metre that moved is payable. Most unit-price contracts pay excavation up to the design lines; digging beyond them (over-excavation, or overbreak in a pit) and work outside the project boundary are usually not paid unless instructed. Check your contract — and measure them separately either way, so the discussion is about a known number.
STREAM's production progress module makes exactly this split. Each project links a boundary area, a design surface and a baseline; for every period the total movement is broken down into in-project production, design overbreak, area without design and unrecorded work, and the findings are listed with project, period and quantity.
Period by period
Two consecutive dated surveys form a period. For each one STREAM reports the days, the in-project production, overbreak, unrecorded work, the total and the weekly rate; with a weekly target it compares the last period against it and projects an estimated completion from the rate of the last three periods.
Because periods are built from the surveys themselves, correcting one survey changes only the two periods on either side of it, and the change shows.
What goes in the file with the payment
The attachment should let a reviewer rebuild the number: the two survey dates, the coordinate system and datum, the method, the boundary, the volume table and drawings that show where the work is. In practice that is a signable PDF report with a report number and the units declared on every page, the station schedule as CSV or Excel, the cross-section drawings and over-break outlines as DXF, and a georeferenced class map as GeoTIFF.
STREAM writes all of these from the numbers shown on screen; the report never recomputes. If the scope is incomplete — a project without a design surface, for example — the outputs are locked and the reasons are listed, so an unfinished quantity is not sent out by mistake.
What STREAM does not do
STREAM measures quantities; it does not price them. Rates, contract items, deductions and the payment certificate itself stay with your contract and accounting tools. Thresholds such as the dead band or the bulking factor start empty and are yours to set: STREAM never invents a site measurement.
Frequently asked questions
How is an earthwork progress payment calculated?
Quantity times rate: the volume of excavation or fill measured between the previous survey and the current one, multiplied by the contract rate for that item. The quantity comes from two dated surveys on the same coordinate system and datum, computed by the method the contract specifies — surface difference or cross-sections.
Should earthworks be paid in in-place or loose volume?
Excavation is usually paid in in-place (bank) volume, the volume measured in the ground; loose volume is larger by the bulking factor. Whichever your contract uses, state it on the quantity.
Is over-excavation paid?
Usually not unless instructed: most unit-price contracts pay excavation up to the design lines. Measure it separately anyway — STREAM's production progress module reports design overbreak per project and period.
Cross-sections or surface difference — which should I use?
Both are accepted. The surface method uses all the measured ground; cross-sections are what many contracts and road specifications require. STREAM runs both on the same surveys, and comparing the two is a good check.
What should a progress payment quantity report include?
The survey dates, the coordinate system and datum, the method, the boundary, the volume table and drawings showing where the work is. STREAM produces a signable PDF report, CSV or Excel tables, DXF cross-sections and over-break outlines and a GeoTIFF class map from the same numbers.
Track earthwork production period by period
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