About Federal Bridge Gross Weight Formula

The Federal Bridge Gross Weight Formula, also known as Bridge Formula B, is a critical mathematical tool utilized in the United States by truck drivers and Department of Transportation (DOT) officials. This formula is instrumental in determining the appropriate maximum gross weight for commercial motor vehicles (CMVs) based on the number of axles and their spacing. Its implementation is integral to federal weight and size regulations for interstate commercial traffic, while intrastate traffic adheres to state-specific limits.


  1. Understanding the Federal Bridge Gross Weight Formula
  2. Compliance and Weigh Stations
  3. Exception to the Formula
  4. Ensuring Roadway Safety
  5. Conclusion
Bridge formula

Understanding the Federal Bridge Gross Weight Formula

The Federal Bridge Gross Weight Formula serves as a safeguard to prevent heavy vehicles from damaging roads and bridges. It’s particularly pertinent for CMVs, which are predominantly tractor-trailers or buses. The formula itself hinges on the configuration of the vehicle, primarily the number of axles and their spacing.

Compliance and Weigh Stations

Compliance with this federal regulation is verified when vehicles pass through weigh stations, often strategically positioned at state borders or the outskirts of major cities. At these stations, CMVs undergo scrutiny, including weight and dimension measurements. This ensures that the vehicles adhere to the prescribed weight limits outlined in the Federal Bridge Gross Weight Formula.

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Exception to the Formula

One notable exception to the formula was introduced at the request of the American Trucking Association. It permits a standard five-axle semi-truck configuration to reach the maximum legal gross weight without violating the bridge formula law. This exception is particularly relevant for tanker trucks, enabling them to transport heavy loads within the confines of the law.

Ensuring Roadway Safety

The Federal Bridge Gross Weight Formula plays a pivotal role in preserving roadway safety. By preventing overloading of CMVs, it safeguards the integrity of roads and bridges, averting potential structural damage and ensuring the safety of both drivers and the public.


Understanding the intricacies of this formula is vital for truck operators, DOT officials, and policymakers alike. It underscores the importance of precision and adherence to federal regulations governing the weight and dimensions of CMVs.

For more information on the Federal Bridge Gross Weight Formula and related regulations, please visit this link. Thorough knowledge and compliance with these standards are integral to maintaining the safety and integrity of the nation’s roadways.

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