Which factor determines the maximum weight allowed per axle?

• A. Bridge formula
• B. Gross vehicle weight rating
• C. Curb weight
• D. Payload

Answer: (A)

The bridge formula is used to determine the maximum load that can be placed on a group of axles based on how many axles there are and how far apart they are. This calculation helps protect bridges by ensuring heavier trucks distribute weight in a way that the structure can safely handle. The per-axle limit isn’t set by the vehicle’s total rating or its empty weight; instead, it depends on the axle arrangement and spacing as defined by the bridge formula.

GVWR describes the maximum total weight of the vehicle, curb weight is the vehicle’s weight without cargo, and payload is the cargo weight—their values relate to overall mass but do not specify how much load each axle may carry.