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CitationsThe regulations in this brochure are found in Code of Federal Regulations (CFR), 23 CFR Part 658. They reflect statutory provisions found in the U.S. Code (USC), 49 USC 31111, 31112, 31113, and 31114. NotesThis pamphlet explains Federal length and width requirements for certain commercial motor vehicles and where these vehicles may operate. It paraphrases the regulations. In case of a dispute, the actual regulations govern. All dimensional units are given in metric and English values in accordance with the Federal Highway Administration metric conversion policy published in the Federa1 Register (FR) on June 11, 1992 (57 FR 24843) and the Notice of Interpretation regarding vehicle size and weight requirements published in the Federal Register on October 7, 1994 (59 FR 51060). FEDERAL SIZE REGULATIONS FOR COMMERCIAL MOTOR VEHICLES (CMVs)The Federal Government first enacted size regulations for CMVs with the passage of the Federal-Aid Highway Act of 1956. This Act provided a maximum vehicle width of 96 inches (2.44 meters) on the Interstate highway system. Subsequently, the Federal-Aid Highway Act of 1976 increased the allowable width for buses to 102 inches (2.6 meters). The Surface Transportation Assistance Act (STAA) of 1982 extended the same width requirement of 102 inches to commercial trucks. At the same time, the STAA expanded the highway network on which the Federal width provision applied from the Interstate to the National Network (NN) of highways. (See discussion of the NN on page 12.) The STAA also regulated the length of CMVs. In 1982, Congress established minimum length standards for most commercial truck tractor-semitrailers and for twin trailers pulled behind a truck tractor. (See discussion beginning on page 2.) Congressional involvement in vehicle length reflected the desire to standardize the enforcement of length along the NN and to thereby eliminate any administrative and operating confusion caused by varying State provisions governing commercial vehicle length along that element of U.S. highways. There is no Federal vehicle height requirement for CMVs. Thus, States may set their own height restrictions. Most height limits range from 13 feet, 6 inches (4.11 meters) to 14 feet (4.27 meters), with exceptions granted for lower clearance on particular roads. WIDTH REQUIREMENTSThe maximum width limit for CMVs on the NN and reasonable access routes was originally established at 102 inches, except for Hawaii where it is 2.74 m (108 inches). (See discussion of Reasonable Access on page 12.) To standardize vehicle width on an international basis, the 102-inch width limit was interpreted to mean the same as its approximate metric equivalent, 2.6 meters (102.36 inches) (Figure 1). Federal width limits do not apply to special mobile equipment, which consists of self-propelled vehicles not designed or used primar-ily for the transportation of persons or property and only incidentally moved over the highways. Special mobile equipment includes the following, when moving under their own power: military or farm equipment; instruments of husbandry; road construction or maintenance machinery; and emergency apparatus, including police and fire emergency equipment. Federal rules do not require States to issue overwidth permits before allowing operation of special mobile equipment. However, if States wish to allow other vehicles more than 102 inches wide (i.e. non-special mobile equipment) to operate on the NN, then States must issue special overwidth permits. Figure 1. Commercial Motor Vehicle Width Limits LENGTH REQUIREMENTSThe Federal length limits are principally minimums that States must allow for the following vehicles on the NN and reasonable access routes. Truck Tractor-Semitrailer CombinationsThe minimum allowable length limit for the semitrailer in this combination is 14.63 m (48 feet) or the grandfathered limit for a particular State. (See discussion of Grandfathered Semitrailer Lengths on page 3.) A State may not impose an overall vehicle length limit on a truck tractor-semitrailer combination operating on the NN or reasonable access routes, even if the trailer is longer than the minimum length required by Federal law (Figure 2). A State may not impose an overall length limit on a truck tractor pulling a single semitrailer or a limit on the distance between the axles of such a truck tractor. Figure 2. Truck Tractor-Semitrailer Combination A truck tractor is defined as a non-cargo-carrying power unit used in combination with a semitrailer. A truck that carries cargo on the same chassis as the power unit and cab, commonly known as a straight truck, is not subject to Federal regulations, but is subject only to State provisions. Likewise a straight truck towing a trailer or semitrailer is subject only to State vehicle length regulation, except that the total length of its two cargo-carrying units may not exceed a federally established limit of 65 feet. (See discussion of ISTEA "Freeze," on page 13.) The only instances where Federal regulations apply to a combination vehicle composed of a truck carrying cargo involve dromedaries, maxi-cube vehicles, and automobile and boat transporters, discussed later in this document. Truck Tractor-Semitrailer-Trailer CombinationsThe minimum length that States must allow for trailers and semitrailers in these combinations on the NN is 8.53 m (28 feet) (Figure 3). States must also allow the continued use of semitrailers 8.69 m (28 feet 6 inches) long that were in use on December 1, 1982, provided the overall length of the combination does not exceed 19.81 m (65 feet). The maximum overall length of cargo-carrying units that States may allow for twin trailer combinations when one trailing unit is longer than 28.5 feet is determined by the Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA). Figure 3. Truck Tractor-Semitrailer-Trailer Combination BusesStates must allow buses 13.72 m (45 feet) in length to operate on the NN and reasonable access routes. Grandfathered Semitrailer LengthsSemitrailers up to the maximum length that were actually and lawfully operating in a truck tractor-semitrailer combination in a State on December 1, 1982, may continue to operate after that date. To clarify what these lengths were for each State, "grandfathered" semitrailer lengths have been established by regulation (Table 1). Table 1. Grandfathered Semitrailer Lengths
Specialized EquipmentLength limits and other provisions have been adopted for six types of specialized equipment: automobile and boat transporter combinations, B-train combinations, beverage semitrailers, maxi-cube vehicles, saddlemount combinations, and dromedaries. Automobile and Boat Transporter CombinationsStates must allow conventional automobile and boat transporters—those with a fifth wheel hitch located on the tractor frame over the drive axle or axles—to be up to 19.81 m (65 feet) in overall length. Automobile transporters are any vehicle combinations designed and used specifically for the transport of assembled highway vehicles, including truck camper units. Camper units are portable units constructed to provide temporary living quarters for recreational, travel, or camping use, consisting of a roof, floor, and sides, designed to be loaded onto and unloaded from the bed of a pickup truck. States must allow "stinger-steered" automobile and boat transporters—those with the fifth-wheel hitch located on a drop frame positioned below and behind the rear tractor axle—to be up to 22.86 m (75 feet) in overall length. To qualify as automobile and boat transporters, under 23 CFR 658.13 (e)(1)(i)-(ii) and (2), both conventional and stinger-steered vehicles must be capable of carrying cargo on the power unit; the cargo may overhang the vehicle by 0.91 m (3 feet) in the front and 1.22 m (4 feet) in the rear (Figures 4, 5, 6, and 7). Boats may also be transported on a straight truck towing a trailer subject to a 19.81 m (65-foot) minimum overall length limit (Figure 8). Figure 4. Conventional Automobile Transporter Combination Figure 5. Stinger-Steered Auto Transporter Combination Figure 6. Conventional Boat Transporter Combination Figure 7. Stinger-Steered Boat Transporter Figure 8. Straight Truck Towing A Trailer Transporting Boats B-Train CombinationsA "B-train" is a truck tractor-semitrailer-semitrailer combination. In this combination, the two trailing units are connected by a fifth wheel attached to a frame under the first semitrailer that extends beyond the rear of that semitrailer (the so-called "B-train" hitch). The second semitrailer connects to the first at this fifth wheel (Figure 9). B-train combinations are subject to the same length limits (65 feet) as truck tractor-semitrailer-trailer combinations. When no semitrailer is attached to the B-train hitch, the assembly is included in the length measurement of the first semitrailer, and the 14.63 m (48-foot), or grandfathered, length applies. Figure 9. B-Train Semitrailer-Semitrailer Combination Beverage SemitrailersThis is a drop frame, side-access semitrailer designed and used to transport and deliver bottled or canned beverages. The upper coupler plate may extend beyond the front of the semitrailer, but not beyond a semicircle whose radius is from the kingpin to the front corner of the semitrailer (Figure 10). The minimum and maximum trailer length is 8.53 m (28 feet) plus the length of the extended upper coupler plate. States may not impose an overall length limit on a truck tractor and beverage semitrailer-trailer combination. Figure 10. Beverage Semitrailer (and Trailer) Maxi-Cube VehiclesThese are combination vehicles consisting of a straight truck and a trailing unit, both of which are designed to carry cargo. The truck has a detachable or permanently mounted cargo box which may be loaded or unloaded through the trailing semitrailer or trailer. In order to qualify as a maxi-cube vehicle under 23 CFR 658.13 (e) (4), neither cargo box may exceed 10.36 m (34 feet) in length, excluding the drawbar or hitching device; the distance from the front of the first to the rear of the second cargo box may not exceed 18.29 m (60 feet), including the space between them; and the overall length of the combination vehicle may not exceed 19.81 m (65 feet), including the space between the cargo boxes (Figure 11). Figure 11. Maxi-Cube Vehicle Saddlemount and Saddlemount with Fullmount CombinationsSaddlemount and saddlemount with fullmount combinations consist of a truck tractor towing other vehicles. The front axle of each towed vehicle is mounted on top of the frame of the vehicle in front. A fullmount is a vehicle mounted entirely on the frame of the first or last vehicle in the combination (Figure 12). States must allow the towing vehicle to pull at least three other vehicles and the combination to have a 22.86 m (75-foot) minimum overall length on the NN and reasonable access routes. Figure 12. Saddlemount with Fullmount Combination DromedariesA dromedary is a box, deck, or plate mounted behind the cab and forward of the fifth wheel on the frame of the power unit of a truck tractor-semitrailer combination to carry freight (Figures 13 and 14). Truck tractors so equipped on December 1, 1982, are subject, during their useful lives, to the same Federal length provisions as any other truck tractor-semitrailer combination. The burden of proving such legal operation on December 1, 1982, rests upon the operator of the equipment. A truck tractor equipped with a dromedary unit pulling a semitrailer where the dromedary unit is transporting Class 1 explosives or any munitions-related security material as specified by the Department of Defense is subject to a 75-foot minimum overall length limit on the NN and reasonable access routes. Each State may decide for itself whether dromedary-equipped power units, other than those noted above, should be treated as a truck tractor-semitrailer combination or as straight trucks under State length limits. Figure 13. Dromedary Box Figure 14. Dromedary Deck or Plate Trucks or Straight TrucksTrucks or straight trucks are non-articulated self-propelled cargo-carrying CMVs (Figure 15). They are subject to Federal weight requirements on the Interstate System and Federal width requirements on the NN, but not to Federal length requirements. Vehicle length regulation remains with the States. Figure 15. Truck or Straight Truck Recreational VehiclesRecreational vehicles are not CMVs subject to Federal size regulations (Figure 16). Figure 16. Recreational Vehicle LENGTH AND WIDTH EXCLUSIVE DEVICESStates must allow certain devices to extend beyond the 2.6 m (102-inch) width limit of CMVs on the NN and reasonable access routes. These include rear-view mirrors, turn signal lamps, handholds for cab entry/egress, splash and spray suppressant devices, and load-induced tire bulge. Also excluded are non-property carrying devices that do not extend more than 3 inches beyond each side of the vehicle. Devices excluded from the measurement of the length include 1) those needed for loading or unloading that do not extend more than 24 inches beyond the rear of the vehicle; 2) resilient bumpers that do not extend more than 6 inches beyond the front or rear of the vehicles; 3) aerodynamic devices that do not extend more than 5 feet beyond the rear of the vehicle, provided they do not have the strength, rigidity, or mass to damage a vehicle or injure a passenger in a vehicle that strikes a trailer so equipped from the rear, and do not obscure tail lamps, turn signals, marker lamps, identification lamps, or any other required safety devices, such as hazardous materials placards or conspicuity markings; and 4) non-property carrying devices that do not extend more than 3 inches beyond the rear of the vehicle. All devices at the front of a semitrailer or trailer are excluded from the measurement of length. Tarping systems for open top trailers or semitrailers are excluded provided no part of the system extends more than 3 inches from the sides or back of the vehicle. For more details on these exclusions, see 23 CFR 658.16 and appendix D to 23 CFR 658. NATIONAL NETWORKThe STAA authorized the establishment of a "National Network" for trucks where Federal width and length limits would apply. It includes the Interstate System and other designated highways which, on June 1, 1991, were a part of the Federal-Aid Primary System in effect at that time. The NN now totals over 321,890 kilometers (km) (200,000 miles) of highways across the Nation. The non-Interstate NN highways are listed in 23 CFR Part 658, appendix A. REASONABLE ACCESSStates must allow CMVs that do not exceed Federal maximum width and minimum length limits applicable to the NN (not including combinations subject to the ISTEA freeze on length) to have reasonable access between the NN and terminals and facilities for food, fuel, repairs, and rest. Terminals are defined as any location where freight originates, terminates, or is handled in the transportation process. Access must be allowed up to 1.61 km (1 mile) from the NN by the most reasonable and practicable safe route. For access to terminal and service facilities beyond 1.61 km (1 mile) from the NN, the route may be requested from the State. Access must be granted if the vehicle can safely travel the route as determined by a test drive. If a State does not act upon a request within 90 days, access is automati-cally granted. If access is granted to one vehicle type, it applies to all vehicles of the same type, regardless of carrier. States must also allow access between the NN and points of loading and unloading to household goods carriers, motor carriers of passengers, and any truck tractor-semitrailer combination in which the trailer or semitrailer has a length equal to or less than 8.53 m (28 feet), or 8.69 m (28.5 feet) for appropriately grandfathered equipment, and which generally operates as part of a truck tractor-semitrailer-trailer combination. ISTEA "FREEZE"ISTEA froze the weights of truck tractors with two or more trailing units operating above 80,000 pounds on the Interstate System at the weight limits actually and lawfully in effect for such vehicles in a State on June 1, 1991. ISTEA also froze the maximum length of the cargo-carrying units of CMVs with two or more such units on the NN. This value may not exceed whatever maximum lengths were actually and lawfully in effect in a State on June 1, 1991. FHWA published a list of weight limits on the Interstate System and length limits on the NN in a final rule on June 13, 1994 (Tables 2A–English units and 2B–metric units). Introductory Notes to Table 2a and Table 2b:Listed for each State by combination type is either:
CMVs are categorized as follows: 1) A CMV combination consisting of a truck tractor and two trailing units, 2) A CMV combination consisting of a truck tractor and three trailing units, 3) CMV combinations with two or more cargo-carrying units not included in descriptions 1 or 2. In the following tables the left number is the maximum cargo-carrying length measured in feet or meters from the front of the first cargo unit to the rear of the last cargo unit. This distance does not include length exclusive devices which have been approved by the Secretary of Transportation or by any State. The right number is the maximum gross weight in thousands of pounds or kilograms that the type of vehicle can carry when operating as an LCV on the Interstate System. Table 2A. Length & Weight Requirements of Vehicles Subject to the ISTEA "Freeze"
NA=Not applicable because Alaska has no Interstate highway system.
NA=Not applicable because Alaska has no Interstate highway system.
U.S. Department of Transportation Phone: 202-366-9210 October 2004 previous | next What's the longest a semi can be?The freight-carrying unit of a tractor semitrailer vehicle usually varies between 40 and 53 feet in length; although, some states allow semitrailer lengths of up to 59′ 6″.
How long is a 18 wheeler truck?The wide variety of available cab styles greatly impacts the average length of an 18 wheeler. Even so, the overall length of a tractor-trailer runs from 70-80 feet in length. This is measured from the center of the rear wheel to the center of the steer.
How long is a trailer of a truck?The standard semi-trailer dimensions, set by the U.S. Department of Transportation, allow for lengths of 48 to 53 feet. That is the standard length the federal government has set for use on highways across the country. Variations in length and height are common, but width is more standardized.
Whats the average lifespan of a semi truck?Average Lifespan of Semi Trucks
A typical semi truck can last up to around 750,000 miles or more. There have even been trucks to hit the one million mile mark! On average, a semi truck drives about 45,000 miles per year. This means that you can probably expect to get about 15 years of use out of your truck.
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