SPMT plan view schematic — two parallel files of 16 axle lines with power pack units at each end

Axle line calculator · indicative · Rev B

SPMT axle line calculator

Enter cargo weight, axle load and ground pressure — the required axle-line count and utilisation update instantly. Every input is serialised to the URL so results are shareable.

Quick check
0 uses the computed minimum — increase to add margin.
Required configuration
— axle lines

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—P_adm
—governing limit
—max util.
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How it works

Diagram showing cargo weight distributed evenly across 6 axle lines above a ground plane

Axle lines

The load is distributed across axle lines. More lines = lower load per line and lower ground pressure.

Plan view showing axle lines divided into three hydraulic groups A, B and C forming a support triangle

Hydraulic grouping

Axle lines are grouped into hydraulic zones. Three-point grouping is statically determinate and the recommended default.

Side elevation showing an axle line footprint on the ground with the formula q = W divided by n times A

Ground bearing pressure

The load footprint of each axle line must stay within the allowable ground pressure. Soft ground or buried services reduce this limit.