Results
Inputs
Choose a unit system, enter section geometry, and include ordering factors. The calculator assumes a trapezoidal ballast section with side slopes.
Formula used
- Bottom width, b = Top width, t + 2 × slope × depth, d
- Area, A = ((t + b) / 2) × d
- In‑situ volume, V = A × length, L
- Order volume = V × bulking factor × (1 + wastage% / 100)
- Mass = Order volume × density
- Truckloads = Mass / truck capacity
How to use this calculator
- Select your unit system (metric or imperial).
- Enter the length, top width, and depth for the ballast layer.
- Set the side slope (H:1V) per your drawings or standards.
- Provide density, then include bulking and wastage allowances.
- Set truck capacity to estimate approximate number of loads.
- Click Calculate to view results above the form.
- Use Download CSV or Download PDF for records.
Example data
| Scenario | Length (m) | Top width (m) | Depth (m) | Slope | Density (kg/m³) | Order vol (m³) | Mass (t) |
|---|---|---|---|---|---|---|---|
| Track segment | 300 | 3.20 | 0.30 | 1.50 | 1600 | 408 | 653 |
| Short siding | 120 | 3.00 | 0.25 | 2.00 | 1550 | 171 | 265 |
| Foundation bed | 60 | 4.00 | 0.20 | 1.00 | 1650 | 71 | 117 |
Ballast quantity planning guide
1) Why quantity accuracy matters
Ballast is frequently ordered in tonnes or truckloads, while drawings define geometry in metres or feet. Converting section dimensions into volume and mass helps prevent shortages, double handling, and idle plant time. Using a consistent section and factors makes procurement and scheduling more reliable across segments.
2) Typical section inputs and ranges
A practical ballast section is often treated as a trapezoid: a top width (formation/shoulder width), a design depth (thickness), and side slopes (H:1V). Common slopes fall around 1.5:1 to 2:1 depending on standards, shoulder requirements, and maintenance practices. Depth and width should match the drawings at the measuring chainage, not a nominal value from a different track class.
3) Density, bulking, and wastage
Ballast density varies by rock type, grading, moisture, and voids. A typical bulk density range is about 1500–1700 kg/m³ (or roughly 90–110 lb/ft³). Ordering often needs an allowance for handling loss and rework; wastage of 3–8% is common for site operations. The bulking/compaction factor accounts for the difference between compacted in-place volume and loose delivered volume; values such as 1.05–1.20 are often used based on experience.
4) From volume to truckloads
Once the order mass is known, dividing by truck capacity provides an approximate number of loads. This supports haul planning, unloading sequence, and stockpile sizing. For mixed supply routes, calculate each haul leg separately and use the higher truck count as a conservative basis for scheduling and access control.
5) Good practice checks before ordering
Confirm whether the design includes crib ballast, shoulder extensions, or transition zones that change geometry. Verify units, density basis (dry vs. moist), and whether capacity limits are by weight or volume. Keep a record of inputs and results using the export options to support quantity tracking and payment measurement.
FAQs
1) What is the “side slope (H:1V)” input?
It is the horizontal run for each 1 unit of vertical rise. A slope of 1.5 means 1.5 units horizontal per 1 unit vertical, used to compute bottom width and section area.
2) Should I enter compacted or loose density?
Enter the density that matches how your supplier invoices. If you know only compacted density, apply an appropriate bulking/compaction factor so the ordered quantity reflects loose delivered material.
3) What bulking/compaction factor should I use?
Use project experience or trial placement results. Many projects start around 1.10 and then refine it using delivered tonnage versus measured placed volume. Keep the factor consistent for comparisons.
4) Why add a wastage percentage?
Wastage covers spillage, contamination, rehandling, and trimming. Even with good controls, some loss occurs in loading, transport, and placement. Use a value that reflects site conditions and access.
5) Does the calculator include shoulders and crib ballast?
It includes what you model in the trapezoid geometry. If shoulders or crib zones increase width or depth, adjust the top width, depth, or slope to match the design section you intend to purchase.
6) How are truckloads calculated?
Truckloads are estimated as total mass divided by truck capacity. The result is approximate because payload may be limited by road regulations, moisture, or loading method. Round up for procurement planning.
7) Can I share the results with my team?
Yes. After calculating, use the CSV export for spreadsheets and the PDF export for site records. These files capture the inputs and computed quantities for traceable communication.