Questions and Answers About Vehicle Size and Weight

23 CFR 658.13 Length

Where do Federal length requirements apply?
Federal length requirements apply to what types of vehicles?
May States establish overall length limits on combination vehicles on the NN and reasonable access routes?
May a State limit the wheelbase of a truck tractor on the National Network when it is part of a combination not subject to an overall length limit?

23 CFR 658.13 Length

Where do Federal length requirements apply?

They apply only on the National Network, which consists of the Interstate System and designated highways as shown in Appendix A to 23 CFR 658, and highways providing reasonable access between the National Network and terminals and facilities for food, fuel, repairs and rest.

Federal length requirements apply to what types of vehicles?

They apply to buses and certain types of combination vehicles, such as truck tractor-semitrailer combinations, truck tractor-semitrailer-trailer combinations and specialized vehicle combinations, such as automobile and boat transporters. The Federal requirements are (except for vehicles subject to the ISTEA freeze, maxi-cube vehicles and beverage semitrailers) minimum lengths. For example, States may not limit the length of the semitrailer in a truck tractor-semitrailer combination to less than 48 feet or a longer grandfathered length (as shown in Appendix B to 23 CFR 658) and may not limit the overall length of the combination. They may not limit the length of the trailing units in twin trailer combinations to less than 28 feet each and may not limit the overall length of the combination. States must allow the overall length of automobile or boat transporter combinations to be at least 65 feet (75 feet if stinger steered). States must allow buses to be a minimum of 45 feet. Other minimums apply for other types of combination vehicles.

May States establish overall length limits on combination vehicles on the NN and reasonable access routes?

Federal law and regulations provide that States may not establish an overall length limit on truck tractor-semitrailer, truck tractor-semitrailer-trailer and truck tractor-semitrailer-semitrailer combinations on the National Network and reasonable access routes. Since the reasonable access provisions do not apply to Rocky Mountain Doubles and Turnpike Doubles, and States are not required to allow them to use the NN, the "no overall length limit" rule applies only on those portions of the National Network where they are allowed to operate.

May a State limit the wheelbase of a truck tractor on the National Network when it is part of a combination not subject to an overall length limit?

No. Limiting the length of the wheelbase could result in a limit on the overall length of the combination.