Width requirements

Scope

These regulations apply to all users of the National Network.

Regulatory citations

• 23 CFR 658.15 — Width

Key definitions

• Commercial motor vehicle (CMV): A motor vehicle designed or regularly used to carry freight, merchandise, or more than ten passengers, whether loaded or empty, including buses, but not including vehicles used for vanpools, or recreational vehicles operating under their own power.
• Interstate system: The National System of Interstate and Defense Highways described in sections 103(e) and 139(a) of Title 23, U.S.C. For the purpose of this regulation this system includes toll roads designated as Interstate.
• National Network (NN): The composite of the individual network of highways from each state on which vehicles authorized by the provisions of the Surface Transportation Assistance Act of 1982 (STAA) are allowed to operate. The network in each state includes the Interstate System. The National network is set out by the Federal Highway Administration (FHWA) in 23 CFR 658 Appendix A.

Summary of requirements

State laws. A state cannot impose a width limitation of more or less than 102 inches on a vehicle operating on the National Network. However, a state can grant special use permits to motor vehicles, including manufactured housing, that exceed 102 inches in width.

Safety devices. Safety devices, as defined in 658.5, 658.16, and Appendix D to Part 658, or as determined by the states as being necessary for the safe and efficient operation of motor vehicles are not to be included in the calculation of width.

Devices not included in 658.5 cannot extend beyond three inches on each side of a vehicle.

No safety device should be capable of carrying cargo.

Exceptions. The State of Hawaii is allowed to keep its 108-inch width maximum.

The width limitations described do not include the special mobile equipment or width exclusive devices defined in 658.5, excluded by 658.16 or Appendix D to Part 658, or which the Department of Transportation Secretary may interpret as necessary for safe and efficient operation of commercial motor vehicles, except that no excluded device can be designed or used for carrying cargo.