In my weight limitations page, I mentioned the limits for vehicles based on how many axles they have. You may notice that for different vehicles, there is a regular weight limit, but that this weight limit increases if you use a Federal Bridge Formula in Connecticut. But what is a Federal Bridge Formula? How can it increase the legal weight of what your truck can carry? On this page, I will discuss the Federal Bridge Formula and how it applies to your truck.

What Is The Federal Bridge Formula?

In 1975, Congress enacted the Bridge Formula. The purpose of the Bridge Formula was to set the maximum weight limit that any motor vehicle can carry on the United States Interstate highway system. The formula is based on the sets of axles of any given vehicle. The formula also sets the weight-to-length ratio limit for vehicles crossing bridges. This ratio is accomplished in one of two ways. First, it could happen by spreading weight out over additional axles. Alternatively, it could happen by increasing the space between axles.

The Formula

The Federal Bridge Formula is as follows:

W = 500 [LN/N-1 + 12N + 36]

In this formula, “W” is the gross weight of the axles that are in a group of two or more consecutive axles to the nearest 500 pounds. “L” is the distance between the outer axles of a group of at least two consecutive axles. This distance is measured in feet. “N” is the number of axles in the group being considered.

In addition to the limits set out by the Federal Bridge Formula, federal laws designate certain weight limitations for trucks. Federal law states that single axles cannot carry more than 20,000 pounds. It also claims that axles that are less than 96 inches apart (tandem axles) have a weight limit of 34,000 pounds. Overall gross weight cannot exceed 80,000 pounds.

The weight on different axle groups and configurations has to be monitored to make sure that the truck is in compliance. To correctly use the Federal Bridge Formula, it is important to understand the terms “gross weight”, “single axle weight”, and “tandem axle weight”. The government limitations for these categories mentioned in this section get used when determining compliance with the Federal Bridge Formula.

Why Use The Federal Bridge Formula?

Interstate highway bridges get designed to support vehicles and their expected weight. To protect and support bridges, a weight limit had to get established for trucks. This weight limit was designed around the axles on different types of trucks. It is important to follow the Federal Bridge Formula to make sure that the bridge in question can sustain the weight of the truck that you are driving.

If you have been accused of not complying with the Federal Bridge Formula, you should contact an attorney as soon as possible. An attorney can help you use the Federal Bridge Formula to defend your position. For more information about the Federal Bridge Formula and overweight trucks, contact us.