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Questions and Answers About Vehicle Size and Weight
23 CFR 658.13(e) Specialized equipment
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?
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?
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.
United States Department of Transportation - Federal Highway Administration