Federal Bridge Formula Calculator/ Federal Bridge Law Calculator 

The Federal Bridge Formula is set by the Federal Highway Administration (FHWA) to ensure safe and efficient movements of loads and commercial vehicles on highways and bridges. This formula defines the maximum allowable weight that can be carried per axle and axle combinations on commercial vehicles. It is primarily concerned with preventing excessive weight from causing damage to bridges and other infrastructure.

Federal Bridge Formula

The formula takes into account several factors, including the spacing between axles, the number of axles, and the overall weight of the vehicle. 

W=500(LN/N-1 + 12N + 36)

W: overall gross weight on any group of two or more consecutive axles to the nearest 500 pounds

L: distance in feet between the extreme of any group of two or more consecutive axles

N: number of axles in the group

Federal Bridge Formula Chart

The federal bridge law calculator visually represents the maximum weight for various axle configurations. This bridge weight calculator can help determine whether your vehicle complies with federal weight regulations.

To understand the federal bridge formula calculator and how to use the chart, it’s important to consider a few key concepts:

Axle Spacing: This refers to the distance between consecutive axles. The formula takes into account both the spacing between adjacent axles and the overall spacing between axles on the vehicle.

Axle Groups: An axle group consists of two or more consecutive axles considered as a single unit. The formula finds the weight carried by each axle group and limits it to prevent excessive stress on the roadway and bridges.

Gross Vehicle Weight Rating (GVWR): This is the maximum allowable weight of a fully-loaded vehicle, including its cargo, fuel, and passengers. The federal bridge formula helps ensure the weight is distributed correctly across all axles and axle groups.