Trucking Industry in The United States - Rules and Regulations - Weight, Size, and Route Restrictions

Weight, Size, and Route Restrictions

See also: Federal Bridge Gross Weight Formula and National Network

The FMCSA regulates the length, width, and weight limits of CMVs for interstate commercial traffic. Interstate commercial traffic is generally limited a network of interstate freeways, U.S. highways and state highways known as the National Network (NN). Provided the truck remains on the NN, they are not subject to the state limits. State limits (which can be lower or higher than federal limits) come into effect for intrastate commercial traffic, provided the vehicle is not on the NN.

There is no federal height limit, and states may set their own limits which range from 13 feet 6 inches (4.11 m) (mostly on the east coast) to 14 feet (4.3 m) (west coast)., As a result, the majority of trucks are somewhere between 13 feet 6 inches (4.11 m) and 14 feet (4.3 m) high. Truck drivers are responsible for checking bridge height clearances (usually indicated by a warning sign) before passing underneath an overpass or entering a tunnel. Not having enough vertical clearance can result in a "top out" or "bridge hit," causing considerable traffic delays and costly repairs for the bridge or tunnel involved.

The federal gross weight limit for a Class 8 truck is 80,000 pounds (36,000 kg) (combined weight of truck, trailer, and cargo). Truck drivers are responsible for checking their own vehicle's weight, usually by paying to be weighed at a truck stop scale. CMVs are subject to various state and federal laws regarding limitations on truck length (measured from bumper to bumper), and truck axle length (measured from axle to axle, or fifth wheel kingpin to axle for trailers). The relationship between axle weight and spacing, known as the Federal Bridge Gross Weight Formula, is designed to protect bridges. Truck weights and sizes are checked by state authorities at a weigh station or port-of-entry.