Bridge laws are a critical part of transportation safety and compliance. These laws regulate how weight is distributed across a commercial vehicle’s axles, as well as the spacing between those axles. Their main purpose is to protect roads and bridges from damage caused by concentrated weight. When properly understood and followed, bridge laws help ensure the safe and efficient movement of freight, reduce the risk of violations, and extend the life of our infrastructure. At the federal level, these regulations are enforced through the Federal Bridge Formula, which is outlined in 23 CFR § 658.17.
In general, the more axles a vehicle has, and the farther apart they are spaced, the more weight it can legally carry — up to the federal gross weight limit of 80,000 pounds. The Bridge Formula is designed to reward well-spaced axle groups by allowing higher axle group weights, provided the overall gross weight remains compliant.
