Explainer

Ground bearing pressure and SPMT moves

How allowable ground pressure limits the number of axle lines you can use — and why the projected-footprint convention matters.

The ground bearing pressure (GBP) check is often the governing limit for SPMT moves on unprepared surfaces. The admissible load per axle line from a GBP perspective is:

P_gbp = q_allow × A_line

where q_allow is the allowable bearing capacity of the ground (t/m²) and A_line is the projected footprint of one axle line (≈ 3.40 m² for a standard 2.43 m wide module at 1.40 m axle spacing).

Full explainer coming soon.