Questions and Answers About Vehicle Size and Weight

It is a written statement issued and signed by a public officer, but not necessarily or customarily sworn to, which is, by law, evidence of the facts stated.

Why are States required to certify that they are enforcing their size and weight laws and regulations "on those highways which, prior to October 1, 1991, were designated as part of the Federal-aid Primary (FAP), Federal-aid Secondary (FAS), or Federal-aid Urban (FAU) Systems?"

This is required under 23 U.S.C. 141(b). However, the ISTEA replaced these designations with the National Highway System (NHS) effective June 1, 1991. The October 1, 1991 date was adopted in the certification to reflect the beginning of the fiscal year. Since 23 U.S.C. 141(b) was not changed and the FAP, FAS and FAU are not coextensive with the NHS, the old designations were retained in the certification.

What constitutes "adequate" enforcement of State size and weight laws?

It is basically compliance with each State's historical level of enforcement and its Annual Enforcement Plan.

If a vehicle is found to be overweight and a citation is issued, must States also require that the load be shifted or unloaded to the legal limit?

No. As long as an enforcement action has been taken, load shifting or unloading is not required, although States may adopt such a practice if they wish.

Must State enforcement of its size and weight laws include enforcement on Indian reservations?

Not where treaties block enforcement of State laws on reservations.

Why doesn't Alaska or Puerto Rico have to certify that they are enforcing their weight limits on the Interstate System?

Because neither has any highways subject to Interstate System weight limits. As a result, they may set limits either higher or lower than the Interstate System weight limits, and are not required to adopt the Federal definition of nondivisible loads or vehicles, since it applies only on the Interstate System. However, they must certify that they are enforcing all size and weight limits on non-Interstate routes which, prior to October 1, 1991, were designated as part of the Federal-aid Primary, Urban and Secondary Systems.

A Governor may designate an "official" to sign the State's certification in his stead. Must the designation include the official's name and/or title?

The certification must include the official's title to show that the person is indeed an official but not necessarily the person's name, i.e., the Governor may designate the "Director of the Department Of Transportation," for example. That way, the certification can be signed by whoever holds the office.

How does NIST's (National Institute of Standards and Technology) work interact with the enforcement of weight laws?

NIST has a voluntary program for the accreditation of State weights and measures laboratories. Absent that accreditation, courts may be reluctant to conclude that State scales are accurate.

Is a minimum penalty (such as $1.00 for the first 1,000 pounds of overweight) consistent with enforcement of weight limits on the Interstate System?

It would be a tolerance in all but name, unless grandfathered.

May States assess fewer than four penalties when one vehicle violates the single axle, tandem axle, gross weight, and bridge formula weight limits on the Interstate System?

No. These are separate legal requirements and failure to assess a penalty for violation of any of them is a tolerance of that overweight, which is prohibited on the Interstate System.

Is RELEVANT EVIDENCE an acceptable weight enforcement technique?

Yes. Under it, States check shipping papers at freight offices to see if vehicles were dispatched overweight. Since only gross weights are normally available, it cannot be viewed as a replacement for scale weighing but only as a supplement. One advantage is that it allows penalties to be assessed against parties who may be more culpable than drivers for overweight violations.

Is a warning issued to a driver of an overweight vehicle an enforcement tool or simply an exemption from the normal weight limit?

It depends. If a State never moves from warnings to actual citations, it is equivalent to an exemption. In addition, warnings should be limited to minor or inadvertent overweights and even then should be severely limited in number. More serious or deliberate violations should be cited immediately. If properly used, warnings can be a legitimate enforcement activity.

Are States required to install weigh-in-motion systems in conjunction with transponder-based scale bypass programs?

Not necessarily if there is some assurance that the bypass technology is adequate to prevent overweight trucks from bypassing open scales so that States may honestly certify that they are adequately enforcing their weight limits.

What vehicles must stop at weigh stations?

States determine what vehicles must stop at weigh stations. Some require all commercial motor vehicles to stop, while others require only those above a certain weight to stop. Ultimately, States must certify that they are enforcing their weight limits on certain highways in order not to jeopardize their receipt of Federal highway funds. Excluding a significant number of heavy vehicles from stopping at weigh stations would be inconsistent with such a certification.

23 CFR 657.19 Effect of failure to certify or enforce State laws adequately, and 49 U.S.C. 31115 Failure to incorporate Federal size requirements into State laws

What sanctions do States face for failure to conform to Federal size and weight laws and regulations?

(1) Failure to certify or adequately enforce size and weight limits on those highways which, prior to October 1, 1991 were designated as part of the Federal-aid Primary, Federal-aid Secondary, or Federal-aid Urban Systems -- 10 percent of National Highway System funds for the next fiscal year. (2) State weight laws for Interstate System not consistent with Federal requirements -- 100 percent of National Highway System funds for the next fiscal year. (3) State size limits not consistent with Federal requirements -- Suit in Federal court for an injunction.

23 CFR 657.21 Procedure for reduction of funds

What options are available to a State if the FHWA alleges that its laws do not reflect Federal Interstate System weight limits or it is not adequately enforcing its size and weight laws?

A State may request a hearing or notify the FHWA that it wishes to resolve the matter informally witin 30 days. If a hearing is requested or the matter cannot be resolved informally, a hearing will be conducted as expeditiously as possible. A hearing may be denied if a violation of only 23 U.S.C. 127 is alleged, since that would be a purely legal matter and not a question of fact that could be resolved in a hearing. If a State does not accept the finding of the FHWA, it may seek judicial review of the matter. This does not cover all the possible actions in a sanction proceeding.

23 CFR 658.11 Additions, deletions, exceptions, and restrictions (to National Network)

Can non-Interstate System designated routes be removed from the National Network?

Yes, subject to approval by the FHWA. 23 CFR 658.11©

Can Interstate System highway segments be removed from the National Network?

Yes, subject to approval by the FHWA. 23 CFR 658.11(d)

May States impose reasonable restrictions on the use of Interstate System routes without approval from the FHWA?

Yes, when they are related to (1) specific travel lanes on multi-lane highways; (2) construction zones; (3) adverse weather conditions; or (4) structural or clearance deficiencies. 23 CFR 658.11(d)(4).

Construction zones may include restrictions to the mainline or ramp(s) of a long or short duration, and include all travel lanes, or specific travel lanes. Information on construction zone restrictions should be disseminated under established State and local procedures. Notice of the restrictions should be provided in advance to the public and to neighboring State and Local DOT's that are affected by the construction. Similar to the intent of 658.11, the Work Zone Safety and Mobility Rule and the associated Transportation Management Plan (TMP) provide a consultative process for the identification of effects on truck traffic caused by work zones and the means to minimize those effects such as detours and notification to the traveling public.

For more information, please see: http://www.ops.fhwa.dot.gov/wz/resources/final_rule.htm and 23 CFR Part 630.1002 to 630.1016.

May States restrict use of the non-Interstate National Network routes by vehicles authorized to operate on those routes under Federal law and regulations without FHWA approval?

Yes, on specific travel lanes of multi-lane highways, restrictions related to construction zones, seasonal operations, adverse weather conditions and structural or clearance deficiencies. 23 CFR 658.11(g).

May States restrict the hours that vehicles subject to Federal size limits may use the National Network?

Yes, subject to approval by the FHWA. 23 CFR 658.11(g)(2)

When the National Network was designated, some States included all Federal-aid primary highways on it without a specific designation. Are they part of the designated network?

Yes. The States' inclusion of them as part of the NN was an automatic designation.

May States restrict trucks to specific lanes on multi-lane highways?

Yes. There are no Federal traffic laws that require all highway lanes to be available to all types of commercial motor vehicles.

What is FHWA’s recommended practice for closures of Interstate highway segments for Special Events?

Due to potential impacts on interstate commerce, FHWA recommends that proposals to close segments of the Interstate System for special events be developed in consultation with the FHWA Division Office. The purpose of the Interstate System includes the safe and efficient transportation of persons and goods. Use of segments of the Interstate System for special events, which may disrupt traffic, impede commerce, or present a potential safety concern to the traveling public is discouraged.

States are responsible for activities occurring on the Interstate System, including approval of special events. Efforts should be made to minimize the closure of Interstate segments, disruption of traffic, and reasonable alternate routes should be provided. In addition, full consideration of the safe operation of detours and connecting facilities must be assured for commercial and passenger vehicles. Information about special event closures should be provided in advance to the public and to State and Local DOTs.

Additional information on Interstate System Access Guidance may be found at: https://www.fhwa.dot.gov/programadmin/fraccess.cfm.

What should the FHWA Division Office consider when consulting with the State on proposals to close Interstate highway segments for special events?

During consultation with the State, the FHWA Division should consider:
Impact on interstate commerce;
Potential safety concerns;
Alternative routes that can safely accommodate commercial motor vehicles of the dimensions and configurations described in sections 658.13 and 658.15;
Duration and location of the closure;
Level of coordination with the local governments in which the segment is located, and the Governor or the Governor's authorized representative of other State(s) that might be affected by such a closure;
The State’s plan for providing advance information to the public and to State DOTs.

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.

23 CFR 658.13(e) Specialized equipment

What features distinguish automobile transporters from noncargo-carrying truck tractor-semitrailer combinations?

Both the power unit and semitrailer are specialized equipment and therefore must be designed to carry automobiles. States must allow them to have 3 feet of cargo overhang at the front of the power unit and 4 feet of cargo overhang at the rear of the semitrailer. States must allow standard or conventional automobile transporters (those with the fifth wheel hitch located over the rear tractor axle or axles) to be a minimum of 65 feet in overall length. Stinger-steered automobile transporters (those where the fifth wheel hitch is located on a drop-frame below and behind the rear-most axle of the power unit) must be allowed a minimum of 75 feet in overall length.

What is the justification for allowing stinger-steered automobile transporter combinations to be longer than traditional automobile transporter combinations?

The preamble to a final rule published January 29, 1988 (53 FR 2593), stated that a 75-foot stinger-steered automobile transporter combination tracked as well as a 45-foot semitrailer combination and tended to jackknife less than a 65-foot automobile transporter combination.

How is the length of automobile transporters measured?

They are measured from the foremost part of the power unit to the rearmost load carrying part of the semitrailer, except for devices excluded from the measurement of length.

May automobile transporters use extendable "flippers" to support automobiles in order to achieve allowable overhangs?

Yes. Extendable ramps or "flippers" on automobile transporters that are used to achieve the allowable 3-foot front and 4-foot rear cargo overhangs are excluded from the measurement of vehicle length, but must be retracted when not supporting vehicles. Front and rear overhangs are operating rights created for and limited to automobile transporters and boat transporters. "Flippers" merely allow modern automobiles which have wheels placed closer to the front and rear bumpers to achieve the allowable overhangs.

May States restrict the length of the power unit or semitrailer in automobile transporter combinations?

No. Allowing States to limit the length of a component part of an automobile transporter might prevent the operator from achieving the full 65 or 75-foot minimum overall length mandated by Federal regulations.

May automobile transporters have an enclosed power unit and/or semitrailer, provided that there are internal modifications in both to accommodate automobiles?

Yes. If both the power unit and semitrailer are designed specifically to transport automobiles, it does not matter if they are enclosed.

May an automobile transporter combination provide a protective covering for automobiles overhanging the front or rear of an automobile transporter?

Yes, provided it does not extend beyond the front or rear of the automobile transporter when not protecting automobiles.

May a State allow more than 3-foot front and 4-foot rear overhang for automobile transporters?

Yes. Federal regulations provide that States may not limit overhangs to "less than" 3 or 4 feet. This is not affected by the ISTEA freeze on length since the freeze applies only to the length of the cargo carrying units and not front or rear cargo overhangs.

May a semitrailer connected to the power unit by a ball and socket hitch be considered an automobile transporter combination?

No. Federal regulations specify that it must be a fifth-wheel hitch.

What is the minimum length that States must allow for boat transporter combinations on the National Network (NN) and reasonable access routes?

The minimum overall length for traditional boat transporter combinations, those with the fifth wheel hitch located on the tractor frame over the rear axle or axles, is 65 feet, and 75 feet for those with a stinger-steered fifth wheel hitch located on a drop frame below and behind the rear-most axle of the power unit. In addition, the minimum overall length for truck-trailer boat transporter combinations is 65 feet. States may regulate their length when no portion of a movement is on the NN.

Do boat transporter combinations include any types different than automobile transporter combinations?

Yes. Boat transporters include not only standard and stinger-steered combinations with fifth-wheel hitches but also straight trucks towing a trailer using typically a ball and socket hitch.

What is the maximum length of boat transporter combinations that States may allow to operate?

Conventional boat transporter combinations over 65 feet or stinger-steered boat transporter combinations over 75 feet may operate only as shown in Appendix C to 23 CFR 658. States may regulate their length when no portion of a movement is on the NN.

What is the minimum length that States must allow for truck tractor-semitrailer-semitrailer (B-train) combinations on the National Network and reasonable access routes?

States must allow the trailing units to be a minimum of 28 feet each, or 28.5 feet if the semitrailer was in legal operation on December 1, 1982, with no overall length limit on the combination on the NN and reasonable access routes. The B-train assembly between the first and second semitrailer is excluded from the measurement of the length of the trailing units. States may regulate the length of B-train combinations when no portion of a movement is on the NN.

How is the length of the semitrailer with a B-train assembly attached measured when used singly?

The B-train assembly is included in the measurement of the semitrailer, subject to a minimum length of 48 feet or a longer grandfathered length.

What is the length requirement for beverage semitrailers?

They may have a noncargo carrying (other than the structure of the semitrailer) upper coupler plate that extends beyond the front of the semitrailer but not beyond its swing radius, measured from the center line of the kingpin to a front corner of the semitrailer. The center line of the kingpin may not exceed 28 feet from the rear of the semitrailer. States may not impose an overall length limit on a truck tractor in combination with 2 trailing units where either or both is a beverage semitrailer, when any portion of a movement is on the NN.

How does the regulation of beverage semitrailers differ from that of standard 28-foot semitrailers?

The measurement of length is from the center line of the kingpin to the rear of the semitrailer and is a maximum and not a minimum distance even when used in a single trailer combination.

What is the minimum length that States must allow for buses on the NN and reasonable access routes?

Forty-five feet.

What makes DROMEDARY BOX, DECK, OR PLATE EQUIPPED POWER UNITS an issue for Federal regulation?

Federal law and regulations prohibit overall length limits for non-cargo carrying truck tractor-semitrailer combinations, plus require minimum semitrailer lengths on the NN and reasonable access routes. If the power units in such combinations were equipped with dromedary units, they would be considered truck-trailer combinations subject to State length limits, unless designated as specialized equipment by the FHWA.

When are power units equipped with dromedary boxes, decks or plates covered by Federal length regulations?

A dromedary equipped power unit in legal operation on December 1, 1982, is specialized equipment that may continue to operate throughout its useful life. Under Federal regulations, it is regulated the same as a truck tractor without a dromedary box, deck, or plate. Proof of legal operation on December 1, 1982, is the responsibility of the operator of the equipment. Similarly, a power unit equipped with a dromedary unit operating in combination with a semitrailer, provided the combination is transporting Class 1 explosives and/or any other munitions related security material as specified by the U.S. Department of Defense, is specialized equipment. No State may impose an overall length limit of less than 75 feet on the combination, whether loaded or empty. The status of such a combination when empty is determined by convincing evidence, such as the content of the previous load and carrier business. States must allow the combination to have reasonable access between the NN and terminals and facilities for food, fuel, repairs and rest. In all other cases, dromedary equipped power units pulling a semitrailer are subject to State length regulations. Dromedary equipped power units pulling semitrailers were not considered when regulations for the ISTEA freeze were promulgated since they were a minor segment of the industry that was not specifically covered by the legislation and are therefore not subject to the ISTEA freeze on the length of the cargo-carrying units. Refer to the preamble to a Final Rule published June 13, 1994 (59 FR 39394).

Are fork lifts attached to the rear of a vehicle as an aid to unloading included in the measurement of the length of the unit?

No. They are considered to be part of the cargo that overhangs the rear of the vehicle. Cargo overhangs, except for the 3-foot front and 4-foot rear automobile and boat transporter overhangs, are subject to State length regulation. However, if the fork lifts are carried on a platform permanently attached to the rear of a semitrailer or trailer, the platform would be part of the vehicle and included in the measurement of its length.

What are the length requirements for a maxi-cube vehicle?

Neither cargo box may exceed 34 feet in length, excluding the hitch. The distance from the front of the first to the rear of the second may not exceed 60 feet, including the hitch, and the overall length may not exceed 65 feet.

What would be the minimum length limit States would have to allow for a maxi-cube type vehicle configured as an automobile transporter, when empty?

It would depend on the content of the previous load. If it was automobiles, 75 feet would be the minimum length States would have to allow. For other commodities, the vehicle would be a maxi-cube vehicle limited to 65 feet in overall length.

Where do maxi-cube length requirements apply?

Only on the National Network and reasonable access routes. States may set whatever limits they wish when no portion of a movement is on the National Network.

What is a motorsports semitrailer or trailer?

It is a semitrailer or trailer used exclusively or primarily in connection with motorsports competition events [Final Rule published March 5, 1997 (62 FR 10179)].

Does the 46-foot kingpin to rear axle requirement for motorsports semitrailers or trailers apply regardless of the type of power unit?

Yes.

Does the 46-foot kingpin to rear axle requirement apply only on the National Network and reasonable access routes?

It applies on the National Network and reasonable access routes between terminals and facilities for food, fuel, repairs, and rest. As indicated in the preamble to a Final Rule published March 5, 1997 (62 FR 10179) which adopted the regulations for motorsports trailers and semitrailers, service facilities include off-track repair shops, storage facilities between races, and similar facilities, provided motorsports semitrailer and trailer combinations could safely travel the routes to and from them.

Unless a longer truck-semitrailer combination was in use in a State on June 1, 1991, the maximum overall length on the National Network is 65 feet. Would this be long enough to accommodate a motorsports semitrailer or trailer with a 46-foot kingpin to rear axle distance?

The regulation applies only on semitrailers or trailers long enough to accommodate a 46-foot distance from the kingpin to the rear axle.

What is the minimum length that States must allow for saddlemount combinations on the National Network and reasonable access routes?

No State may impose an overall length limit of less than 75 feet and must allow up to 3 saddlemounted vehicles, plus one fullmounted vehicle.

What is the maximum length of saddlemount combinations that States may allow to operate?

Saddlemount combinations over 75 feet in length may operate only if they were in legal operation in a State on June 1, 1991, and then only on routes where they could operate at that time, as shown in Appendix C to 23 CFR 658. For example, Wyoming. States may determine their length when no portion of a movement is on the National Network.

23 CFR 658.15 Width

What is the minimum/maximum width that States must allow on the National Network?

It is 102 inches or its approximate metric equivalent, 2.6 meters (102.36 inches), except that Hawaii is allowed to keep its 108-inch maximum width limit.

Does a 102-inch wide commercial motor vehicle carrying cargo that extends more than 102-inches in width require an overwidth permit on the NN and reasonable access routes?

Yes. Width limits are primarily safety regulations and would be less effective if cargo was not included.

Does the Federal 102-inch minimum/maximum width limit on the NN apply on non-commercial vehicles, such as recreational vehicles?

No. It applies only on commercial motor vehicles.

23 CFR 658.16 Exclusion from length and width determinations

What are some of the more significant types of non-cargo carrying devices excluded from the measurement of the width and/or length of commercial motor vehicles?

Five (5) items are excluded regardless of how far they extend beyond the exterior of vehicles; rear view mirrors, turn signal lamps, handholds for cab entry/egress, splash and spray suppressant devices, and load induced tire bulge. Other excluded devices are (1) all non-property carrying devices or components at the front of a semitrailer or trailer, (2) devices that do not extend more than 3 inches beyond each side or the rear of a vehicle, devices needed for loading or unloading that do not extend more than 24 inches beyond the rear of the vehicle, and (3) aerodynamic devices that do not extend more than 5 feet beyond the rear of a vehicle, provided they have neither the strength, rigidity nor mass to damage a vehicle that strikes a trailer so equipped from the rear and provided also that they do not obscure tail lamps, turn signals, market lamps, identification lamps, or any other required safety features, such as hazardous materials placards or conspicuity markings. For more excluded devices, 23 CFR 658.16 and Appendix D to 23 CFR 658.

Is a 2 1/4-inch step bar on the sides of a vehicle designed to provide a place for someone to stand while loading and/or unloading automobiles excluded from the measurement of the width of automobile transporters?

Yes. It extends less than 3 inches beyond the sides of automobile transporters.

Are clips, hooks, or other fasteners for fabric sides used to enclose automobile transporters excluded from the measurement of width as tarp hardware?

No. A fabric "curtainside" is not the same as a tarp. Nevertheless, clips, hooks, or fasteners are excluded if they do not extend more than 3 inches beyond each side.

23 CFR 658.17 Weight

What is the minimum/maximum gross weight limit that States must enforce on the Interstate System?

It is 80,000 pounds, unless a lower weight is derived from the bridge formula, or a higher weight is grandfathered.

May States set weight limits on the Interstate System at less than the Federal maximum weight limits?

No. When Interstate System weight limits were raised to the current levels in 1974 (20,000 pounds single axle, 34,000 pounds tandem axle, 80,000 pounds overall gross weight limits, plus bridge formula limits), States were not required to raise their limits accordingly, although most did. However, six contiguous States in the Mississippi Valley, referred to as the "barrier States," did not and effectively limited the weight for all vehicles moving across them to their own limits. This was changed in 1982 when Congress established Interstate System weight limits as minimums as well as maximums.

Are grandfathered weights minimums?

No. States may lower grandfathered weights (but not below Federal minimum weight limits) and raise them to the grandfathered maximum at a later date if they wish.

What is the definition of a single axle?

It is one or more axles not more than 40 inches apart. If two axles are less than 40 inches apart, they are considered to be a single axle.

What is the minimum/maximum single axle weight limit that States must enforce on the Interstate System?

It is 20,000 pounds or a higher grandfathered weight.

What is the definition of a tandem axle?

It is two or more consecutive axles over 40 inches but not over 96 inches apart. If there were 3 axles within that distance, they would be considered a tandem axle for the purpose of Interstate weight limits.

What is the minimum/maximum tandem axle weight limit that States must enforce on the Interstate System?

It is 34,000 pounds or a higher grandfathered weight.

What is the bridge formula?

It is a mathematical formula designed to protect bridges by establishing a maximum weight for all groups of two or more consecutive axles on a vehicle.

Are weights derived from the bridge formula minimums as well as maximums?

Yes.

What weight limit applies when the single or tandem axle, gross, or bridge formula limits result in different maximum weight limits?

Whichever is the lowest. To do otherwise would violate whatever weight limit was exceeded.

When is "rounding" appropriate?

When, for example, values are given in whole.

How are bridge formula weights determined when distances between axles are not in whole feet?

Since the bridge formula is a Federal requirement, rounding is a policy question vested in the FHWA. Since the purpose of the bridge formula is to protect bridges, the appropriate policy is to round down when the distance between axles exceeds the nearest foot by less than 6 inches. When the distance exceeds the nearest foot by 6 inches or more, a State may decide for itself whether to round up or down to the nearest foot.

As shown in the bridge formula pamphlet, may a State round 8-foot, 1-inch down to 8-foot?

No. A State may only round down to the next lower bridge formula weight limit, i.e., "more than 8 feet," since the 34,000 pound tandem axle weight limit does not apply at axle distances over 8 feet.

If a State had grandfathered weight limits in a commercial zone after 1956 and sometime later the size of the commercial zone was increased, would the higher weight limits apply in the enlarged zone?

No. Grandfather rights would continue to apply only where they applied in 1956.

Does the Secretary have authority to waive Interstate System weight limits in an emergency?

No. Federal law and regulations do not provide any authority to set aside or waive Federal weight requirements on the Interstate System. Furthermore, weight laws on the Interstate System are actually State laws. Federal law simply provides that States must adopt and enforce Federal weight laws or lose Federal highway funds. Even if Federal weight requirements were waived, State laws would still apply.

Are there any circumstances where the Secretary may waive Interstate System weight limits?

Yes. Section 1064 of the National Defense Authorization Act for Fiscal Year 2002 amended 23 U.S.C. 127 to allow the Secretary, in consultation with the Secretary of Defense, to waive the Interstate System weight limit on I-95 between Augusta and Bangor, Maine, for bulk shipments of jet fuel to the Air National Guard at Bangor International Airport in an emergency. Generally, however, Congress has not provided authority for waivers but has statutorily established either specific higher weight limits or grandfather dates that do so.

What are grandfather rights?

They arise from 23 U.S.C. 127(a) and allow State weight limits to exceed normal Federal weight limits on the Interstate System. Under the first grandfather right, a State may allow vehicles to operate at higher than normal single axle, tandem axle, and/or gross weight limits if such weights were permitted on its public highways on July 1, 1956. Under the second grandfather right, a State may allow vehicles to operate at higher than normal bridge formula or axle spacing weight limits if such weights were permitted on its public highways on January 4, 1975. Exceptions: the date of all grandfather rights for Michigan is May 1, 1982; for Maryland June 1, 1993; and for the first grandfather right in Hawaii, February 1, 1960.

Where do grandfather weights apply?

They apply only on the Interstate System and routes providing reasonable access between it and terminals and facilities for food, fuel, repairs and rest.

May States that reduce grandfather weights subsequently raise them?

Yes. Grandfather weights are vested on the date specified by Congress and are not affected even if a State chooses to adopt a lower limit for some period of time. States may not reduce grandfather weights below normal Interstate weight limits.

What is the significance of a vehicle or cargo being nondivisible?

States may issue permits for nondivisible vehicles or loads to exceed Interstate System weight limits or ISTEA freeze length limits.

May States issue nondivisible overlength permits for vehicles or cargo to exceed the maximum length of the cargo-carrying units of vehicles with two or more such units imposed by the ISTEA freeze?

Yes, although as a practical matter, they will rarely be needed since they would usually apply only on loads, such as buildings, that are moved on a series of dollies, each of which is a single cargo-carrying unit, or long loads such as rockets that would require two overlength cargo-carrying units (States would be free to regulate the length of front and rear overhangs, if any).

On what highways does the Federal definition of nondivisible apply?

(1) For nondivisible overweight vehicles or loads, the Interstate System and highways providing reasonable access to and from it. (2) For combinations with 2 or more cargo carrying units subject to the ISTEA freeze on length, highways shown in Appendix C to 23 CFR 658.

If a vehicle or load cannot be dismantled in 8 hours using appropriate equipment, must it be dismantled to whatever extent is possible in 8 hours?

No. If a vehicle or load cannot be dismantled in 8 hours, it is nondivisible and a State may issue a nondivisible overweight permit. However, if parts are removed to facilitate transportation of an overweight load, they cannot be loaded on the same vehicle.

Are some vehicles and articles defined by regulation as nondivisible?

Yes. States may treat emergency response vehicles, such as firetrucks used to protect persons and property from fires and other disasters that threaten public safety (but not trucks carrying relief supplies), casks designed for the transport of spent nuclear materials and vehicles carrying marked military materiel as nondivisible vehicles or loads. Vehicles under lease or contract to the military would not qualify as nondivisible.

May States consider intermodal shipping containers to be nondivisible?

States may consider containers moving in international commerce as nondivisible but are not required to do so.

Does the 8-hour rule in the definition of nondivisible vehicles or loads include reassembly time?

No. It includes only disassembly time.

Does the 8-hour rule in the definition of nondivisible vehicles or loads include the labor of one or more persons?

It means 8 person hours, i.e., 8 hours for one person, 4 hours apiece for two persons, or 2 hours apiece for 4 persons.

If a blade must be removed from a bulldozer because it is overwidth even though the removal takes more than eight hours, may the blade and power unit be considered a nondivisible load?

No. It is not nondivisible if it has already been divided.

Is a concrete pumper truck carrying water in a tank and lengths of pipe, both necessary to the pumping operation, nondivisible?

No. The water is infinitely divisible and could be carried to the site in another vehicle, as could the pipe.

Do SPREAD OR SPLIT TANDEMS (Two consecutive axles more than 96 inches apart.) axles qualify for the exception to the bridge formula that allows two consecutive sets of tandem axles between 36 and 38 feet apart to carry 68,000 pounds?

No. The exception applies only for tandem axles more than 40 inches but not over 96 inches apart.

May States limit the maximum weight of steering axles on the Interstate System to less than 20,000 pounds?

They may limit the weight to 20,000 pounds or the axle weight rating established by the manufacturer, whichever is lower.

May States limit the weight per inch of tire or tread widths?

States may limit tire loads on the Interstate System, but not to less than 500 pounds per inch of tire or tread widths. Tire load limits may not be applied to steering axles.

May States allow vehicle weight tolerances above Interstate System weight limits?

No. Federal law specifically prohibits this. All Interstate weight limits must include all enforcement tolerances.

May VARIABLE LOAD SUSPENSION, BOOSTER, CHEATER, DUMMY OR TAG axles be included in determining maximum weight limits under the Federal Bridge Formula on the Interstate System?

Each State may determine for itself whether or not to do so. Some States require that such axles carry a minimum amount of weight or that the control be outside the cab in order to be counted as an axle under the bridge formula.

23 CFR 658.19 Reasonable Access

What is reasonable access?

There are two kinds. (1) Under 23 CFR 658.19(a), States must allow commercial motor vehicles subject to Federal length and width requirements to have reasonable access between the National Network and terminals and facilities for food, fuel, repairs and rest, plus they must allow buses, household goods carriers using STAA vehicles, and under 23 CFR 658.13 (5)(iii), truck tractor and single beverage semitrailer combinations, to have access to points of loading and unloading. (2) Under 23 U.S.C. 127(b) States must allow vehicles subject to Interstate System weight limits to have reasonable access between that system and terminals and facilities for food, fuel, repairs and rest. The FHWA has not adopted regulations to implement this requirement but access must be reasonably related to safety and highway and bridge capacities. Access under this requirement has not presented much of a problem since State weight limits are generally the same or higher than Interstate System weight limits, except in some Mississippi Valley States.

What access is reasonable for commercial motor vehicles subject to Federal length and width requirements?

States must allow access for one-mile (except for specific safety requirements) on individual routes and beyond one mile via any route that a test drive or application of vehicle templates to plans of the route show that a vehicle subject to Federal width and length requirements could safety negotiate. States must respond to a request for the designation of an access route within 90 day or the route is automatically approved.

Must States allow reasonable access routes to be used as through routes or shortcuts between National Network highways?

No. However, States may allow such use without violating Federal rules.

Does reasonable access require local authorities to allow a truck tractor to be parked at a driver's home?

No. Federal rules require States to allow Surface Transportation Assistance Act (STAA) vehicles to have reasonable access between the National Network and terminals and facilities for food, fuel, repairs and rest. A truck tractor is not an STAA vehicle. In addition, there may be zoning restrictions against using a home as a terminal or a facility for food, fuel, repairs and rest.

What constitutes "reasonable" access between the NN and points of loading and unloading?

The same standards that determine whether access between the NN and terminals and facilities for food, fuel, repairs and rest is reasonable, i.e., can the route be safely traversed by the vehicle in question?

What kind of household goods carrier vehicles must States allow to have reasonable access between the NN and points of loading and unloading?

Only commercial motor vehicles with lengths and widths that States must allow to operate on the NN, but not including vehicles subject to the ISTEA freeze on length that may operate on the NN under provisions of Appendix C to 23 CFR 658.

What access must be allowed for a household goods carrier whose cargo includes one or more automobiles along with other household goods?

They must be allowed the same access as a household goods carrier whose cargo does not include automobiles.

What access must be allowed for a household goods carrier using an automobile transporter not over 65 feet in length (75 feet if stinger steered) to transport automobiles?

They must be allowed the same access as any other automobile transporters of those lengths, i.e., to terminals and facilities for food, fuel, repairs and rest.

Must States allow vehicles longer and wider than required by Federal law to have reasonable access between the NN and terminals and facilities for food, fuel, repairs, and rest?

No. States are not required to allow vehicles wider and longer than required by Federal law to operate on the NN and therefore they are not required to allow them to have reasonable access beyond it. This can produce anomalies, since a State with a grandfathered 53-foot semitrailer length must allow them to have reasonable access, whereas a State with a 48-foot minimum semitrailer length may determine what access they will allow for those 53-foot long.

May States require a permit as a condition for allowing reasonable access?

No. Access may be denied only on the basis of a safety and engineering analysis of an access route, usually by driving over it. Lack of a permit is not a permissible reason to deny access.

Must a State publish a list of reasonable access routes or erect highway signs showing such routes?

No. However, all States must make information regarding their reasonable access provisions available to commercial motor vehicle operators.

Would an automobile transporter configured to transport school buses be entitled to reasonable access between the National Network and terminals and facilities for food, fuel, repairs and rest?

Yes. However, access routes must be requested from a State in advance in order to allow time to determine if they are safe. Routes to schools may not have been evaluated for safety since they are not usual commercial destinations and therefore authority to use such routes may be delayed.

What is the maximum length that States may allow for semitrailers in a B-train combination?

They may allow semitrailers up to 28 feet (28.5 feet, if grandfathered) in length. If either is longer, they are subject to the ISTEA freeze on the overall length of the cargo carrying units, including the hitch between the semitrailers, as shown in Appendix C to 23 CFR 658.

23 CFR 658.23 LCV freeze; cargo carrying unit freeze (ISTEA freeze)

What does LCV mean?

It stands for "longer combination vehicle."

What is the ISTEA freeze?

ISTEA is an acronym for Intermodal Surface Transportation Efficiency Act of 1991. It imposed two separate freezes: (1) on the maximum weight of longer combination vehicles, which consist of any combination of a truck tractor and two or more trailers or semitrailers which operate on the Interstate System at a gross weight over 80,000 pounds; and (2) on the overall length of the cargo carrying units of combination vehicles with two or more such units where one or both exceed 28.5 feet in length on the National Network. The maximum weight of longer combination vehicles and the maximum length of the cargo carrying units of combination vehicles is the weight or length in actual and legal operation in a State on June 1, 1991, as documented in Appendix C to 23 CFR 658. Also frozen were the routes and conditions in effect on June 1, 1991, for vehicle combinations subject to the freeze, as shown in Appendix C to 23 CFR 658.

Did the freeze on conditions include height limits and the amount of insurance coverage?

No. These are not related closely enough to the length and weight limitation goals of the ISTEA to be covered by the freeze.

Since the ISTEA froze the length of the cargo-carrying units for combinations with two or more such units, does it also prevent the Secretary from authorizing longer lengths for specialized equipment?

No. While States may not authorize longer lengths for specialized equipment (e.g., automobile and boat transporters) the Secretary may take whatever action is necessary to accommodate the use of specialized equipment on the NN and reasonable access routes.

If, in the future, the Secretary authorized longer lengths for specialized equipment, would States have to allow them to use existing reasonable access routes?

No. Under present regulations, States would have the opportunity to alter access routes if they determined that existing routes would not be safe for longer specialized vehicle combinations.

Are longer combination vehicles subject to standard or grandfathered Interstate System weight limits?

Neither. They are subject only to the maximum weight limits documented in Appendix C to 23 CFR 658 as being in effect on June 1, 1991.

Are longer combination vehicle maximum weights also minimums?

No. States may reduce them (but not below Interstate minimums) and raise them to the longer combination vehicles maximums at a later date if they wish.

How is the length of the cargo carrying units measured?

The length is measured from the foremost load carrying structure of the first unit to the rearmost load carrying structure of the last unit, including the hitch or hitches between the units, but excluding the upper coupler on a beverage semitrailer.

What combination vehicles are not covered by the ISTEA freeze on length?

(1) Twin trailer combinations where neither trailing unit exceeds 28.5 feet in length, (2) automobile and boat transporters where neither trailing unit exceeds 65 feet in overall length (75 feet, if stinger steered), (3) saddlemount combinations not over 75 feet in overall length, (4) truck tractors equipped with a dromedary box, deck, or plate, (5) truck trailer and truck semitrailer combinations not over 65 feet in overall length, and (6) maxi-cube vehicles.

Is the length of tow trucks with vehicles in tow subject to the ISTEA freeze on length?

No. They are excluded from the freeze on the length of the cargo carrying units. States are free to regulate their length.

What is the maximum length of automobile transporter combinations that States may allow to operate?

Automobile transporter combinations over 65/75 feet may operate on NN and access routes only as shown in Appendix C to 23 CFR 658.

Are articulated buses subject to the ISTEA length freeze?

No, because they are not readily separable into two units and, in addition, the freeze applies to combinations with two or more cargo carrying units and passengers are neither property nor cargo.

23 CFR 658.5 Definitions

What is an automobile transporter?

It is a vehicle combination designed and used specifically to transport assembled highway vehicles including truck camper units on both its power unit and semitrailer.

What vehicles may automobile transporters carry to qualify as such?

They may transport assembled highway vehicles including truck camper units that are not self propelled, provided they are capable of operating on highways, i.e., they must have wheels, except wheel-less units designed to be loaded on the bed of a pickup truck may also be transported. They may not transport wrecked automobiles or those used solely to compete in motorsports competition since neither could legally operate on highways, as noted in a Final Rule published December 22, 1998 (63 FR 70650).

Is a noncargo carrying power unit and a semitrailer designed and used to carry automobiles an automobile transporter?

No. It is a truck tractor-semitrailer combination. A semitrailer does not lose its identity as such regardless of its appearance or the cargo it may be carrying.

Does a power unit with an empty head rack pulling a semitrailer configured to transport automobiles qualify as an automobile transporter?

Yes. The presence of a headrack, even though empty, means that the power unit is capable of carrying cargo.

May automobiles be transported on noncargo-carrying truck tractor-semitrailer combinations as well as on automobile transporters?

Yes. Unlike automobile transporters that may transport only automobiles, noncargo-carrying truck tractor-semitrailer combinations may carry any type of cargo including automobiles. States would be free to regulate the length of cargo allowed to overhang the front or rear of such combinations.

May automobile transporters transport freight other than automobiles?

No. If they should, on rare occasions, transport something other than automobiles, they would lose their identity as such and, due to their ability to carry cargo on the power units, would be considered truck-semitrailer combinations.

Is an enclosed 48-foot or longer grandfathered length semitrailer with interior racks that carries automobiles one way and general freight on the return an automobile transporter?

Not unless the power unit is also configured to carry automobiles and then only when carrying automobiles or returning empty.

What are B-trains?

They are truck-tractor semitrailer-semitrailer combinations where the front semitrailer has a fifth wheel hitch mounted on the rear as a hitch for the second semitrailer.

What is a beverage semitrailer?

It is a drop frame semitrailer designed and used to transport bottled or canned beverages (including water) with side-only cargo access.

What is a boat transporter combination?

A vehicle combination designed and used specifically to transport assembled boats and boat hulls that may be partially disassembled to facilitate transportation.

What is a bus?

A bus is a commercial motor vehicle designed or regularly used to carry more than 10 passengers (11 including the driver) but not including vanpools. (Definition of Motor Carriers of Passengers)

What is a dromedary box, deck, or plate?

It is a cargo-carrying unit mounted on the frame of the power unit behind the cab and forward of the fifth wheel hitch.

What types of goods qualifies a carrier as a "household goods carrier?"

Personal effects and property used or to be used in a dwelling by a householder when part of the equipment or supply of such dwelling, as provided in 49 U.S.C. 13102 (10).

What is a longer combination vehicle (LCV)?

It is any combination of a truck tractor and two or more trailers or semitrailers which operates on the Interstate System at a gross vehicle weight greater than 80,000 pounds.

What is a maxi-cube vehicle?

It is a straight truck pulling a semitrailer or trailer, with both units capable of being loaded or unloaded through the trailing unit.

What is the National Network?

It consists of the Interstate System and designated highways on which States must allow vehicles subject to Federal size limits to operate, as shown in Appendix A to 23 CFR 658.

What is the National Highway System?

It is the Federal-aid system on which States may spend Federal Highway funds. It was designated by the States in consultation with the FHWA and includes the Interstate System. It is designed to serve major population centers, international border crossings, ports, airports, public transportation facilities and other major travel destinations.

Do Federal weight and size requirements apply on the National Highway System?

Federal weight limits apply on the Interstate System, which is also part of the National Highway System. Federal size limits apply on the National Network and would apply on the National Highway System only where the same highway was on both systems.

What does nondivisible mean?

It means any load or vehicle exceeding applicable length or weight limits which, if separated into smaller loads or vehicles, would: (1) Compromise the intended use of the vehicle, i.e., make it unable to perform the function for which it was intended; (2) Destroy the value of the load or vehicle, i.e., make it unusable for its intended purpose; or (3) Require more than 8 workhours to dismantle using appropriate equipment. The applicant for a nondivisible load permit has the burden of proof as to the number of workhours required to dismantle the load. A State may (but is not required to) treat emergency response vehicles, casks designed for the transport of spent nuclear materials, and military vehicles transporting marked military equipment or materiel as nondivisible vehicles or loads.

What are recreational vehicles?

They are generally a vehicular-type unit primarily designed as temporary living quarters for recreational, camping, travel, or seasonal use that either has its own motive power or is mounted on, or towed by, another vehicle. (From American National Standards Institute)

Are recreational vehicles subject to Federal size and reasonable access requirements?

No, because they are not commercial motor vehicles.

Are recreational vehicles subject to Interstate axle weight limits?

Yes.

Are recreational vehicles required to stop at State scale sites?

Each State may set its own requirements.

What is a saddlemount combination?

It is a combination of vehicles where a truck or truck tractor tows one or more trucks or truck tractors, each towed vehicle connected by a saddle to the frame or fifth wheel of the vehicle in front.

May vehicles in a saddlemount combination be towed backwards?

No. The definition specifies that the "saddle" connects the front axle of the towed vehicle to the frame or fifth wheel of the vehicle in front.

Federal regulations require States to allow saddlemount combinations with "up to three" saddlemounted vehicles. Does "up to three" mean two or three?

Three. Unlike other units of measurement, where "up to $3.00" may mean $2.99, motor vehicles are not divisible and "up to three" cannot mean 2.99 vehicles. In this context, the obvious meaning of "up to three" is "as many as three."

What is a fullmount?

It is a smaller vehicle mounted completely on the frame of either the first or last vehicle in a saddlemount combination.

What is special mobile equipment?

They are self-propelled vehicles not designed or used primarily for the transportation of persons or property and incidentally moved over the highways.

What is the significance of the special mobile equipment designation?

Special mobile equipment is excluded from Federal width requirements on the National Network and therefore States may regulate their width (23 CFR 658.7).

Does overwidth special mobile equipment require a permit when transported on a regular commercial motor vehicle?

Yes. Special mobile equipment is excluded from Federal width limits only when moved under their own power. These are normally short movements that pose little hazard to the traveling public. When moved on a CMV, they become like any other high speed, over the road, movement.

Is farm equipment such as plows, rakes, etc. that do not have an integral power unit special mobile equipment when powered by a farm tractor?

Yes. A farm tractor serves as an interchangeable power unit for them.

What are STAA vehicles?

While this term has never been defined, it is used to denote vehicles for which the Surface Transportation Assistance Act of 1982 (STAA) provided width and length requirements. These are principally truck tractor-semitrailer combinations with 48 feet or longer grandfathered length semitrailers and twin trailer combinations where neither exceeds 28 feet in length, plus specialized equipment such as automobile and boat transporters. STAA vehicles must be accorded reasonable access between the NN and terminals and facilities for food, fuel, repairs, and rest.

What is a truck tractor?

It is a noncargo carrying power unit that operates in combination with a semitrailer or trailer. A truck tractor and semitrailer engaged in the transportation of automobiles may transport cargo (motor vehicles) on part of the power unit.

Does a truck tractor with a sleeper cab qualify as noncargo carrying?

Yes. Unlike a dromedary box, a sleeper cab does not carry cargo but is part of the driver's cab.

What highways and vehicles do federal laws and regulations cover?

Federal weight limits apply to all vehicles on the Interstate System. Federal laws and regulations involving length and width of vehicles apply to the National Network, which includes the Interstate System plus other arterial routes designated by the states and the federal government.

What are the National Network and the National Highway System?

The National Network consists of the Interstate System and designated highways on which States must allow vehicles subject to Federal size limits to operate, as shown in Appendix A to 23 CFR 658. The National Highway System is the Federal-aid system on which States may spend Federal Highway funds.
For more information, visit the National Network and National Highway System Web sites.

23 CFR 658.9 National Network Criteria

Must traffic lanes on the National Network be 12 feet wide?

A traffic lane on the National Network (NN) is required to be designed to have a width of 12 feet or more or be otherwise consistent with highway safety [see 23 CFR 658.9(b)(5)]. There are several tools and methodologies that can be applied to determine the safety and operational impacts of design decisions which include the Highway Safety Manual (HSM), the Highway Capacity Manual (HCM), and performance-based practical design

For portions of the NN that are also part of the NHS, design standards can be found in 23 CFR part 625. Guidance on NHS Design Standards and Design Exceptions are available at https://www.fhwa.dot.gov/design/standards/qa.cfm.

Miscellaneous

May States allow vehicle weight tolerances above Interstate System weight limits?

No. Federal law specifically prohibits this. Interstate weight limits must include all enforcement tolerances.

May States allow scale tolerances?

States may allow up to a 5-percent tolerance for portable scales (wheel-load weighers).

May States allow weight tolerances on the non-Interstate System portions of the Federal-aid Primary, Federal-aid Secondary, and Federal-aid urban systems?

Yes, but they must be authorized by State law or regulations since States must certify annually that they are enforcing their weight laws and regulations on these systems which, prior to October 1, 1991, were designated as Federal-aid primary, Federal-aid secondary, and Federal-aid Urban.

Which Federal agency has jurisdictional and regulatory responsibility for the routing of hazardous material?

As of October 1, 2000, it is the Federal Motor Carrier Safety Administration.

Are there any Federal height requirements for commercial motor vehicles?

No, States may set whatever height limits they believe are appropriate. Typically, the height limits range between l3' 6" and 14'.

Is U.S. 93 across Hoover Dam on the NN?

U.S. 93 on the Arizona side of the dam is not on the NN. However, in Nevada it is on the NN up to where the Bureau of Reclamation jurisdiction begins. The dam itself is owned by the Bureau of Reclamation which has authority to establish traffic regulations on the highway across the dam and could prohibit commercial motor vehicles from using it if they chose to do so.

How may size and weight numerical units be converted to metric units?

The FHWA published a Notice of Interpretation on October 6, 1994 (59 FR 51060) explaining how size and weight requirements may be converted into metric units.

What is a permit?

A permit is an exceptional authorization issued to a motor carrier allowing it to transport oversize or overweight cargo. It is available for a limited period of time and tailored to the needs of each particular vehicle or load.

May States issue overwidth permits "by operation of law" for vehicles on the National Network and reasonable access routes?

No, because it would be a permanent exemption issued unilaterally without evaluating the safety of a vehicle or even requiring an application.

Are there any Federal size and weight regulations for pilot cars?

No. They are subject to State regulation.

May a State participate in a joint port of entry that is wholly within another State?

Yes. However, there may be legal questions regarding the ability of one State to successfully prosecute overweights when the weighing facility is located in a neighboring State. Utah and Arizona and some other States maintain joint ports.

May radar detectors be used in commercial motor vehicles?

No. The FHWA issued a Final Rule December 21, 1993 (58 FR 67370) prohibiting them (This is a safety regulation that is now under the jurisdiction of the Federal Motor Carrier Safety Administration).

Is there a national speed limit?

No. The national speed limits were eliminated in 1995 and responsibility for speed control reverted to the States.

May commercial motor vehicles operate on the 22 miles of U.S. 191 that goes through the northwest corner of the Park?

Yes. The National Park Service published a Final Rule on August 25, 1994 (59 FR 43731) which provided that commercial motor vehicles may operate on this highway, except vehicles transporting hazardous materials must secure a permit from the Park Superintendent (36 CFR 7.13).

Where are federal regulations on vehicle size and weight published?

Federal regulations involving vehicle size and weight are published in 23 CFR 658. This part includes a list of highways in each state that are part of the National Network.