Check axle loads for safer compliant hauling. Estimate group loads with clear assumptions. Export clean summaries for projects and inspectors.
| Axle | Static load (kN) | Notes |
|---|---|---|
| 1 | 58.0 | Steer axle |
| 2 | 76.0 | Drive axle |
| 3 | 76.0 | Drive axle |
| 4 | 68.0 | Trailer axle |
| 5 | 68.0 | Trailer axle |
Managing axle loads is a practical way to protect pavements and keep heavy vehicles within legal limits. A single overloaded axle can create disproportionate damage, especially on flexible pavements and thin overlays. This calculator helps you total gross vehicle weight, compare axle groups against limits, and estimate relative pavement impact using a fourth‑power screening approach.
Many road agencies publish limits for single, tandem, and tridem groups. Common baseline values used for preliminary checks are about 80 kN for a single axle, 160 kN for a tandem, and 240 kN for a tridem, but regional rules may vary by spacing, tire type, and road class. For example, a tandem at 170 kN would exceed a 160 kN threshold and may require load redistribution or route restrictions.
Static scale readings do not capture impact from suspension response and surface roughness. A dynamic load factor is a convenient way to screen this effect. In this tool, the factor increases with speed and is capped at 1.30. At 60 km/h, a factor near 1.12 is possible depending on the suspension selection, meaning a 70 kN static axle could behave like roughly 78 kN under impact.
The equivalent single axle load concept compares different axle loads to a standard axle (80 kN or 18 kip). The calculator applies the fourth‑power rule: impact is proportional to (effective load / standard load)4. That means doubling the effective axle load increases the screening damage index by 16 times. This highlights why small overloads can matter on weak pavements.
When direct axle readings are unavailable, you can estimate front and rear group reactions using basic statics. With gross weight W, wheelbase L, and CG distance a from the front group, the rear reaction is W×a/L and the front reaction is W−rear. The tool then distributes each reaction across the axles in that group. Use measured geometry for best results.
Use certified scale readings for each axle when possible. Enter the correct axle count, choose the proper unit, and match limits to your jurisdiction. Estimation mode is helpful when scales are not available.
Effective load is the static axle load multiplied by the dynamic load factor. It is a screening value to reflect impact from speed and suspension response, not a replacement for instrumented measurements.
ESAL screening uses the fourth‑power relationship. Because the load ratio is raised to the power of four, even modest increases in effective axle load can produce a much larger relative impact index.
The tool groups axles sequentially: pairs for tandem and triples for tridem. It then compares each group’s summed static load to your entered group limit. If your regulations use spacing rules, adjust limits accordingly.
Yes. Select the unit you prefer and enter all values in that unit. The calculator converts internally and reports results in the same unit, including group checks and the downloadable summaries.
Direct mode supports up to eight axles, so you can enter each axle load and run mixed checks. For estimation mode, the simplified statics model uses one front group and one rear group.
No. Defaults are common baseline values used for quick screening. Always replace them with the exact limits for your country, road class, and permit conditions before using the results for compliance decisions.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.