Compilation of Existing State Truck Size and Weight Limit Laws
Report to Congress
May 2015
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The Honorable Bill Shuster
Chairman
Committee on Transportation and Infrastructure
U.S. House of Representatives
Washington, DC 20515
Dear Mr. Chairman:
I am pleased to submit this Report to Congress, prepared in accordance with Section 32802 of the Moving Ahead for Progress in the 21st Century Act (MAP-21) legislation, compiling State truck size and weight limit laws in force as of October 1, 2012.
This report addresses laws related to the National Highway System (NHS) of which the Interstate Highway System roadways are a subset. The States determine laws and regulations affecting truck size and weight on portions of the NHS that are not also a part of the Interstate System.
Current truck size and weight standards are a blend of Federal and State regulations and laws. Federal law controls maximum gross vehicle weights and axle loads on the Interstate System. Federal limits are 80,000 pounds gross vehicle weight, 20,000 pounds on a single axle, and 34,000 pounds on a tandem axle group. There are also Federal standards for length and width on the National Network (NN). The NN comprises the Interstate and certain roadways designated by the States. There are no Federal vehicle height limits.
The report demonstrates that all States have laws in place to ensure compliance with Federal size and weight requirements. The report also shows that in some instances, States have laws that allow sizes and weights on non-Interstate highways in excess of the current Federal truck size and weight limits. This is an expected finding, as State laws control maximum gross vehicle sizes and weights on non-Interstate highways, including the NHS.
I have sent a similar letter to the Ranking Member of the House Committee on Transportation and Infrastructure and to the Chairman and Ranking Member of the Senate Committee on Environment and Public Works. If I can provide further information or assistance, please feel free to call me.
Sincerely yours,
[Signature on file]
Anthony R. Foxx
Enclosure
The Honorable Peter A. DeFazio
Ranking Member
Committee on Transportation and Infrastructure
U.S. House of Representatives
Washington, DC 20515
Dear Congressman DeFazio:
I am pleased to submit this Report to Congress, prepared in accordance with Section 32802 of the Moving Ahead for Progress in the 21st Century Act (MAP-21) legislation, compiling State truck size and weight limit laws in force as of October 1, 2012.
This report addresses laws related to the National Highway System (NHS) of which the Interstate Highway System roadways are a subset. The States determine laws and regulations affecting truck size and weight on portions of the NHS that are not also a part of the Interstate System.
Current truck size and weight standards are a blend of Federal and State regulations and laws. Federal law controls maximum gross vehicle weights and axle loads on the Interstate System. Federal limits are 80,000 pounds gross vehicle weight, 20,000 pounds on a single axle, and 34,000 pounds on a tandem axle group. There are also Federal standards for length and width on the National Network (NN). The NN comprises the Interstate and certain roadways designated by the States. There are no Federal vehicle height limits.
The report demonstrates that all States have laws in place to ensure compliance with Federal size and weight requirements. The report also shows that in some instances, States have laws that allow sizes and weights on non-Interstate highways in excess of the current Federal truck size and weight limits. This is an expected finding, as State laws control maximum gross vehicle sizes and weights on non-Interstate highways, including the NHS.
I have sent a similar letter to the Chairman of the House Committee on Transportation and Infrastructure and the Chairman and to the Ranking Member of the Senate Committee on Environment and Public Works. If I can provide further information or assistance, please feel free to call me.
Sincerely yours,
[Signature on file]
Anthony R. Foxx
Enclosure
The Honorable James M. Inhofe
Chairman
Committee on Environment and Public Works
United States Senate
Washington, DC 20510
Dear Chairman Inhofe:
I am pleased to submit this Report to Congress, prepared in accordance with Section 32802 of the Moving Ahead for Progress in the 21st Century Act (MAP-21) legislation, compiling State truck size and weight limit laws in force as of October 1, 2012.
This report addresses laws related to the National Highway System (NHS) of which the Interstate Highway System roadways are a subset. The States determine laws and regulations affecting truck size and weight on portions of the NHS that are not also a part of the Interstate System.
Current truck size and weight standards are a blend of Federal and State regulations and laws. Federal law controls maximum gross vehicle weights and axle loads on the Interstate System. Federal limits are 80,000 pounds gross vehicle weight, 20,000 pounds on a single axle, and 34,000 pounds on a tandem axle group. There are also Federal standards for length and width on the National Network (NN). The NN comprises the Interstate and certain roadways designated by the States. There are no Federal vehicle height limits.
The report demonstrates that all States have laws in place to ensure compliance with Federal size and weight requirements. The report also shows that in some instances, States have laws that allow sizes and weights on non-Interstate highways in excess of the current Federal truck size and weight limits. This is an expected finding, as State laws control maximum gross vehicle sizes and weights on non-Interstate highways, including the NHS.
I have sent a similar letter to the Ranking Member of the Senate Committee on Environment and Public Works and to the Chairman and Ranking Member of the House Committee on Transportation and Infrastructure. If I can provide further information or assistance, please feel free to call me.
Sincerely yours,
[Signature on file]
Anthony R. Foxx
Enclosure
The Honorable Barbara Boxer
Ranking Member
Committee on Environment and Public Works
United States Senate
Washington, DC 20510
Dear Senator Boxer:
I am pleased to submit this Report to Congress, prepared in accordance with Section 32802 of the Moving Ahead for Progress in the 21st Century Act (MAP-21) legislation, compiling State truck size and weight limit laws in force as of October 1, 2012.
This report addresses laws related to the National Highway System (NHS) of which the Interstate Highway System roadways are a subset. The States determine laws and regulations affecting truck size and weight on portions of the NHS that are not also a part of the Interstate System.
Current truck size and weight standards are a blend of Federal and State regulations and laws. Federal law controls maximum gross vehicle weights and axle loads on the Interstate System. Federal limits are 80,000 pounds gross vehicle weight, 20,000 pounds on a single axle, and 34,000 pounds on a tandem axle group. There are also Federal standards for length and width on the National Network (NN). The NN comprises the Interstate and certain roadways designated by the States. There are no Federal vehicle height limits.
The report demonstrates that all States have laws in place to ensure compliance with Federal size and weight requirements. The report also shows that in some instances, States have laws that allow sizes and weights on non-Interstate highways in excess of the current Federal truck size and weight limits. This is an expected finding, as State laws control maximum gross vehicle sizes and weights on non-Interstate highways, including the NHS.
I have sent a similar letter to the Chairman of the Senate Committee on Environment and Public Works and to the Chairman and Ranking Member of the House Committee on Transportation and Infrastructure. If I can provide further information or assistance, please feel free to call me.
Sincerely yours,
[Signature on file]
Anthony R. Foxx
Enclosure
Table of Contents
Introduction: Purpose, Development Process, and Structure
Background of United States Truck Size and Weight Limits
The Federal-Aid-Highway Amendments Act of 1974 and the Federal Bridge Formula
Typical Truck ConfigurationsSingle Unit (SU) or Straight Trucks
Combination Trucks
Longer Combination Vehicles (LCVs)
Exemptions to Federal Weight Limits
The Intermodal Surface Transportation Efficiency Act (ISTEA), Freeze
Appendix A: State Truck Size and Weight Laws
Appendix B: Summary of State Exceptions to Federal Truck Weight Limits
Table of Exhibits
Exhibit 1: State Truck Size and Weight Profiles
Exhibit 2: National Network Vehicle Size and Weight Standards
Exhibit 3: Federal Bridge Formula Weight Table
Exhibit 4: Common Vehicle Configurations in the U.S. Commercial Truck Fleet
Exhibit 5: Permitted Longer Combination Vehicles on the National Highway System: 2011
Exhibit 6: Chronology of Federal Size and Weight Laws, 1956-Present
Exhibit 7: Common State Statute Exemptions
Exhibit 8: Summary of Alabama Truck Weight Limits for Vehicles in Regular Operations
Exhibit 9: Summary of Alaska Truck Weight Limits for Vehicles in Regular Operations
Exhibit 10: Summary of Arizona Truck Weight Limits for Vehicles in Regular Operations
Exhibit 11: Summary of Arkansas Truck Weight Limits for Vehicles in Regular Operations
Exhibit 12: Summary of California Truck Weight Limits for Vehicles in Regular Operations
Exhibit 13: Summary of Colorado Truck Weight Limits for Vehicles in Regular Operations
Exhibit 14: Summary of Connecticut Truck Weight Limits for Vehicles in Regular Operations
Exhibit 15: Summary of Delaware Truck Weight Limits for Vehicles in Regular Operations
Exhibit 16: Summary of District of Columbia Truck Weight Limits for Vehicles in Regular Operations
Exhibit 17: Summary of Florida Truck Weight Limits for Vehicles in Regular Operations
Exhibit 18: Summary of Georgia Truck Weight Limits for Vehicles in Regular Operations
Exhibit 19: Summary of Hawaii Truck Weight Limits for Vehicles in Regular Operations
Exhibit 20: Summary of Idaho Truck Weight Limits for Vehicles in Regular Operations
Exhibit 21: Idaho Designated 129,000-pound Routes
Exhibit 22: Summary of Illinois Truck Weight Limits for Vehicles in Regular Operations
Exhibit 23: Summary of Indiana Truck Weight Limits for Vehicles in Regular Operations
Exhibit 24: Indiana Heavy-Duty and Extra Heavy-Duty Highway Map
Exhibit 25: Summary of Iowa Truck Weight Limits for Vehicles in Regular Operations
Exhibit 26: Summary of Kansas Truck Weight Limits for Vehicles in Regular Operations
Exhibit 27: Summary of Kentucky Truck Weight Limits for Vehicles in Regular Operations
Exhibit 28: Summary of Kentucky Truck Weight Limits for Non-Divisible Loads
Exhibit 29: Kentucky Truck Weight Classification Map 2013
Exhibit 30: Kentucky Coal Haul Highway System Map 2013
Exhibit 31: Summary of Louisiana Truck Weight Limits for Vehicles in Regular Operations
Exhibit 32: Summary of Maine Truck Weight Limits for Vehicles in Regular Operations
Exhibit 33: Summary of Maryland Truck Weight Limits for Vehicles in Regular Operations
Exhibit 34: Summary of Massachusetts Truck Weight Limits for Vehicles in Regular Operations
Exhibit 35: Summary of Michigan Truck Weight Limits for Vehicles in Regular Operations
Exhibit 36: Summary of Minnesota Truck Weight Limits for Vehicles in Regular Operations
Exhibit 37: Summary of Mississippi Truck Weight Limits for Vehicles in Regular Operations
Exhibit 38: Summary of Missouri Truck Weight Limits for Vehicles in Regular Operations
Exhibit 39: Summary of Montana Truck Weight Limits for Vehicles in Regular Operations
Exhibit 40: Summary of Nebraska Truck Weight Limits for Vehicles in Regular Operations
Exhibit 41: Summary of Nevada Truck Weight Limits for Vehicles in Regular Operations
Exhibit 42: Summary of New Hampshire Truck Weight Limits for Vehicles in Regular Operations
Exhibit 43: Summary of New Jersey Truck Weight Limits for Vehicles in Regular Operations
Exhibit 44: Summary of New Mexico Truck Weight Limits for Vehicles in Regular Operations
Exhibit 45: Summary of New York Truck Weight Limits for Vehicles in Regular Operations
Exhibit 46: Summary of North Carolina Truck Weight Limits for Vehicles in Regular Operations
Exhibit 47: Summary of North Dakota Truck Weight Limits for Vehicles in Regular Operations
Exhibit 48: Summary of Ohio Truck Weight Limits for Vehicles in Regular Operations
Exhibit 49: Summary of Oklahoma Truck Weight Limits for Vehicles in Regular Operations
Exhibit 50: Summary of Oregon Truck Weight Limits for Vehicles in Regular Operations
Exhibit 51: Summary of Pennsylvania Truck Weight Limits for Vehicles in Regular Operations
Exhibit 52: Summary of Rhode Island Truck Weight Limits for Vehicles in Regular Operations
Exhibit 53: Summary of South Carolina Truck Weight Limits for Vehicles in Regular Operations
Exhibit 54: Summary of South Dakota Truck Weight Limits for Vehicles in Regular Operations
Exhibit 55: Summary of Tennessee Truck Weight Limits for Vehicles in Regular Operations
Exhibit 56: Summary of Texas Truck Weight Limits for Vehicles in Regular Operations
Exhibit 57: Summary of Utah Truck Weight Limits for Vehicles in Regular Operations
Exhibit 58: Summary of Vermont Truck Weight Limits for Vehicles in Regular Operations
Exhibit 59: Summary of Virginia Truck Weight Limits for Vehicles in Regular Operations
Exhibit 60: Summary of Washington Truck Weight Limits for Vehicles in Regular Operations
Exhibit 61: Summary of West Virginia Truck Weight Limits for Vehicles in Regular Operations
Exhibit 62: Summary of Wisconsin Truck Weight Limits for Vehicles in Regular Operations
Exhibit 63: Summary of Wyoming Truck Weight Limits for Vehicles in Regular Operations
Glossary of Terms
| AASHTO | American Association of State Highway and Transportation Officials |
|---|---|
| Auxiliary Power Unit | A type of "idle reduction technology" that powers accessories in commercial vehicles to avoid idling for long periods while stopped (such as during rest periods). |
| Axle Spacing | Method of computing distance between axles for bridge formula calculations. Typically measured from center of axle to center of axle between outermost wheel or wheel cluster. The image below identifies axle-spacing for a sample five-axle combination vehicle.
|
| A-Dolly and A-Train Combinations | The A-dolly converter is towed from a single hitch at the centerline of the tow vehicle. The A-Train is a class of articulated vehicle combinations consisting of a tractor and two or more trailers that are coupled together using an A-dolly between trailers.
|
| B-Dolly and B-Train Combinations | The B-dolly is a converter connected by two or more pintle hook couplers and drawbar connections between vehicles in a combination. The resulting rigid connection has one pivot point. The B-Train combination is a trailer assembly that extends from the frame of the first trailer to the fifth wheel of the second trailer attached by a B-dolly. 
|
| CFIRE | Center for Freight & Infrastructure Research & Education |
| CFR | Code of Federal Regulations |
| Divisible/Non-Divisible Loads | Definitions vary by State: generally, a divisible load is one that can be reduced in size or weight, or that is practically divided in a way that does not diminish value or inhibit its intended purpose. A non-divisible load is defined in 23 CFR 658.5 as "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 work hours to dismantle using appropriate equipment. The applicant for a non-divisible load permit has the burden of proof regarding the number of work hours required to dismantle the load. A State may treat emergency response vehicles, casks designed for the transport of spent nuclear materials, and military vehicles transporting marked military equipment or materiel as non-divisible vehicles or loads." |
| Federal Bridge Formula (FBF) | In 1975 Congress enacted the FBF to limit the length-to-weight ratio of vehicles as a means of protecting the Nation's bridges. The FBF is calculated using the following formula: where:
W = Overall gross weight on any group of two or more consecutive axles to the nearest 500 pounds |
| Fire Trucks | States refer to trucks equipped for fighting fires several different ways, including fire trucks, fire apparatus, firefighting equipment, fire-fighting vehicles, and fire engines. For simplification, this report refers to all of these vehicles as fire trucks. |
| FHWA | Federal Highway Administration |
| Fifth wheel | The fifth wheel coupling provides the link between a semitrailer and the towing truck, tractor unit, leading trailer, or dolly. The coupling consists of a coupling pin (or king pin) on the front of the semitrailer and a horseshoe-shaped coupling device on the rear of the towing vehicle. |
| Gross vehicle weight (GVW) | The total combined weight of the vehicle and load. |
| Kingpin to rear axle setting | A common vehicle dimension for governing the turning performance of tractor semitrailer combinations; typically the distance is measured from the kingpin to the center of the rear axle or rear axle group. |
| Longer Combination Vehicle (LCV) | Any combination of a truck tractor and two or more trailers or semitrailers that operate on the Interstate Highway System at a gross vehicle weight of greater than 80,000 pounds. |
| NCSL | National Conference of State Legislatures |
| National Highway System (NHS) | The National Highway System (NHS) was created by the National Highway System Designation Act of 1995. The NHS consists of roadways important to the Nation's economy, defense, and mobility serving major freight and passenger nodes across all transportation modes. The NHS includes the following subsystems of roadways (note that a specific highway route may be part of more than one subsystem):
|
| National Network (NN) | The National Network was authorized by the Surface Transportation Assistance Act of 1982 (P.L. 97-424) and specified in the U.S.C. of Federal Regulations (23 CFR 658) to require that States allow conventional combinations on "the Interstate System and those portions of the Federal -aid Primary System … serving to link principal cities and densely developed portions of the States … [on] high volume route[s] utilized extensively by large vehicles for interstate commerce … [which do] not have any unusual characteristics causing current or anticipated safety problems." Conventional combinations are tractors with one semitrailer up to 48 feet in length or with one 28-foot semitrailer and one 28-foot trailer, and they can be up to 102 inches wide. (All States today allow 53-foot semitrailers on at least some highways.) The National Truck Network (NN) differs in extent and purpose from the National Highway System (NHS), which was created more than a decade later by the National Highway System Designation Act of 1995 (P.L. 104-59) and modified in 2012 by the Moving Ahead for Progress in the 21st Century Act (P.L. 112-141). The NN was originally established in 1982 to protect interstate commerce by prohibiting restrictions on trucks of certain dimensions on a national network of roads, while the NHS supports interstate commerce by focusing Federal highway transportation investments.2 |
| Oversize/Overweight Permit | State-issued permits that allow vehicles of certain configurations and sizes to exceed size and weight limitations. Can be issued as multiple trip (blanket) or single trip permits. |
| Pounds (lbs.) | A unit of mass customarily used in the United States that can be divided into 16 ounces. One pound (lb.) is equivalent to 0.4536 kilograms (kg). |
| Pounds per inch width of tire | A measure of load restriction based on rated tire size. The lbs. per inch of tire width are determined by dividing the weight carried on the axle group by the number of tires in the group and dividing by the manufacturer's rated tire width as indicated on the sidewall of the tire. |
| Rocky Mountain Double | A twin trailer combination classified as an LCV consisting of a tractor, a long semitrailer (45-48 ft.), and a short trailer (25-28 ft.). |
| Saddlemount Vehicle | A truck tractor used specifically to tow other vehicles by mounting the front axle of each towed vehicle to the vehicle in front of it. |
| Snow Plows | States refer to trucks equipped for snow removal several different ways, including snow plows, snow removal equipment, and snow plowing vehicles. For simplification, this report refers to all of these vehicles as snow plows. |
| SU | Single Unit commercial vehicle |
| Superload | Many State oversize/overweight permitting offices refer to loads that exceed normal or automated permitting dimensions or weights as superloads. Superloads typically require manual checks for dimension clearances or bridge evaluations for weight capability. Recent research for National Cooperative Highway Research Program project 20-60A (Scan 12-01) found that, while most State permitting offices refer to superloads, no common definition exists as to what constitutes a superload. |
| Tractor Semitrailer (TST) vehicle combination | The most common commercial motor vehicle combination, consisting of a single tractor unit pulling a single semitrailer. The typical TST has five axles (an "18 wheeler") but, depending on configuration and use, can vary from four axles to six or more. |
| Tandem Axle |  Two or more consecutive axles whose centers may be included between parallel transverse vertical planes spaced more than 40 inches and not more than 96 inches apart, extending across the full width of the vehicle. The Federal tandem axle weight limit on the Interstate System is 34,000 lbs. The image to the right illustrates a tandem axle with dual tires. |
| Tow Trucks | Trucks equipped and used for the purpose of towing, pulling, or otherwise removing disabled or illegally parked vehicles. Tow trucks are also referred to as wreckers, boom trucks, or recovery trucks and can include flat-bed trucks with a tiltable bed. |
| Tridem Axle | 
A group of three axles connected by a common suspension system, or any three consecutive single axles whose extreme centers may be included between parallel transverse vertical planes spaced not more than a specified distance apart, extending across the width of the vehicle, and are articulated from a common attachment to the vehicle, or are designed to automatically equalize the load between the three axles. The image to the right illustrates a tridem axle with dual tires. |
| Triple | A triple trailer combination classified as an LCV consisting of a tractor, a short semitrailer (25-28 ft.), and two short trailers (25-28 ft.). These short trailers are referred to in the industry as "pup trailers." |
| Turnpike Double | A twin trailer combination classified as an LCV consisting of a tractor, a long semitrailer (45-48 ft.), and a long trailer (45-48 ft.). |
| Twin trailer combination | A commercial motor vehicle combination consisting of a single tractor pulling two semitrailers. The Surface Transportation Assistance Act (STAA) Double is a twin trailer vehicle configuration consisting of a tractor, a 28 ft. semitrailer, and a 28 ft. trailer. The STAA Double is allowed nationwide on the Interstate and the NN. |
| Wheelbase (WB) | The wheelbase length is typically provided in metric units (meters) followed English units (feet). |
INTRODUCTION: PURPOSE, DEVELOPMENT PROCESS, AND STRUCTURE
This Report to Congress on the Compilation of Existing State Size and Weight Limit Laws fulfills the requirements of Section 32802 of the Moving Ahead for Progress in the 21st Century Act (MAP-21). Section 32802 requires the Secretary of Transportation to develop a compilation of State laws that were in effect on or before the enactment of MAP-21 (October 1, 2012), and enabled vehicles to operate on segments of the National Highway System (NHS) in excess of current Federal truck size and weight limits.
In accordance with Section 32802, the compilation of State laws was completed in consultation with the States through a partnership with the Association of State Highway and Transportation Officials (AASHTO). The compilation includes:
- A list for each State, as applicable, that describes each route of the NHS that allows a vehicle to operate in excess of the Federal truck size and weight limits that—
- Was authorized under State law on or before the date of enactment of MAP-21; and
- Was in actual and lawful operation on a regular or periodic basis (including seasonal operations) on or before the date of enactment of MAP-21.
- A list for each State, as applicable, that describes—
- The size and weight limitations applicable to each segment of the NHS;
- Each combination that exceeds the Interstate weight limit, but that the U.S. Department of Transportation, other Federal agency, or a State agency has determined on or before the date of enactment of MAP-21, could be or could have been lawfully operated in the State and;
- Each combination that exceeds the Interstate weight limit, but that the Secretary determines could have been lawfully operated on a non-Interstate segment of the NHS in the State on or before the date of enactment of MAP-21; and
- A list of each State law that designates or allows designation of size and weight limitations in excess of Federal law and regulations on routes of the NHS, including non-divisible loads.
To complete the required compilation of State laws and regulations, a list of statutory limitations and exemptions for each State was developed using statutes and other online resources from State agencies.
The information for each State was compiled into a State Truck Size and Weight Profile using the format shown in Exhibit 1.
Exhibit 1: State Truck Size and Weight Profiles
State Summary
- Links to State statutes, administrative code, or online State publications;
- Summary of State Provisions that Exceed Federal Limits;
- Regular Operations (truck limits for operations without a special permit).
Exemptions and Special Operations
- Commodity exemptions;
- Emission reduction/special fuel exemptions;
- Other exemptions;
- Permits for overweight vehicles.
Routes
All the State profiles, with the exception of North Dakota and South Dakota,3 were validated by State agency representatives using the AASHTO Subcommittee for Highway Transport members as the primary point of contact in each State. When contacted, each State representative was asked to review the profile for consistency with their State regulations and enforcement practices. The National Conference of State Legislatures (NCSL) also reviewed the State profiles to verify the completeness, accuracy, and timeliness of each summary with respect to State statutes as they were in place on or before the date of enactment MAP-21 ( October 1, 2012). Where appropriate, NCSL also noted any subsequent changes to State law since that date.
Because Federal truck length limits are permissive (e.g., Federal laws prescribe the minimum dimensions States must allow on the NN) and because there are no Federal limits for vehicle height, the information in the compilation focuses primarily on vehicle weight and State laws or regulations that allow trucks to travel on non-Interstate elements of the NHS at weights greater than allowed by Federal Interstate limits.4 On the NN, no State may impose a width limitation of more or less than 102 inches. At the time this report was compiled, there were no instances discovered in which State laws enable vehicles to operate in excess of this standard, other than through the issuance of oversize permits.
This report is structured with two main components. The first component is a section providing background on U.S. truck size and weight limits and discusses exemptions to Federal truck size and weight limits. The second component comprises two appendices.
The two appendices are described as follows:
Appendix A, fulfills the requirements for the Report to Congress pursuant to MAP-21 Section 32802, containing an opening discussion of common State exemptions to Federal size and weight limits standards and a by-State Compilation of Truck Size and Weight Laws (State profiles). In accordance with MAP-21 Section 32802, each State profile contains information, as applicable, that describes each route of the NHS that allows a vehicle to operate in excess of the Federal truck size and weight limits that:
- Were authorized under State law on or before the date of enactment of MAP-21; and
- Were in actual and lawful operation on a regular or periodic basis (including seasonal operations) on or before the date of enactment of MAP-21.
Each profile also includes a list for each State, as applicable, that describes:
- The size and weight limitations applicable to each segment of the NHS;
- Each combination that exceeds the Interstate weight limit, but that the U.S. Department of Transportation, other Federal agency, or a State agency has determined on or before the date of enactment of MAP-21, could be or could have been lawfully operated in the State; and
- Each combination that exceeds the Interstate weight limit, but that the Secretary determines could have been lawfully operated on a non-Interstate segment of the NHS in the State on or before the date of enactment of MAP-21.
The profiles also list the laws in each State that designate or allow designation of size and weight limitations in excess of Federal law and regulations on routes of the NHS, including non-divisible loads. Information in each of the profiles is current as of August 2014.
Appendix B outlines State exceptions to Federal truck weight limits. This table is derived from 23 CFR 658 Appendix C, which contains the weight and size provisions that were in effect on or before June 1, 1991 (July 6, 1991 for Alaska), for vehicles covered by 23 U.S.C. 127(d) (LCVs) and 49 U.S.C. app. 2311(j) [commercial motor vehicles (CMV) with two or more cargo-carrying units]. The table also includes State exceptions to Federal limits on the Interstate System based on the provisions codified in Title 23 USC§127.
BACKGROUND OF UNITED STATES TRUCK SIZE AND WEIGHT LIMITS
The first laws establishing limits on truck weight in the United States were enacted by several States in 1913. By 1933, all States had established some laws regulating the size and weight of trucks operating on their highways. The Federal Government began regulating truck size and weight in 1956 when Congress passed, and President Dwight D. Eisenhower signed, the National Interstate and Defense Highways Act (Public Law 84-627), establishing the Interstate Highway System. The first Federal truck size and weight regulations limited combination trucks to an overall gross vehicle weight of 73,280 lbs., limited single axle weights to 18,000 lbs., and restricted tandem axle weights to 32,000 lbs. Trucks were limited to a width of 8 feet (96 inches), but the height and length of vehicles were subject only to State law. The Federal limits established in 1956 also came with an exception: Any State that had allowed axle loads or gross vehicle weight (GVW) limits in excess of the 1956 Federal limits could continue to allow the higher State limits on Interstate Highways. This provision in Public Law 84-627 became known as the first "grandfather clause."
Under the first grandfather clause, the Federal Highway Administration (FHWA) (known as the Bureau of Public Roads prior to 1966) had the authority to determine whether specific grandfather claims would be allowed. Although no formal approval process was established, informal procedures soon evolved. In general, a State seeking to establish grandfather rights would submit copies of the appropriate 1956 statute to the FHWA. The agency would review the claim, and, if it determined that the documentation was ambiguous or otherwise arguable, FHWA would request an attorney general's opinion. Claims that were not legally defensible were rejected.
During the 1960s and 1970s, most grandfather issues related to interpreting State laws in effect in 1956 were addressed. States occasionally make new claims, mostly for exemptions from Federal weight limits. However, most grandfather rights were established decades ago.5 In 1974, Congress passed a bill allowing States to increase weight limits on the Interstate Highway System to a maximum of 80,000 lbs. GVW and allowed axle load limits to increase to 20,000 lbs. on a single axle and 34,000 lbs. on a tandem axle. The increase, however, was not a mandate, and some States did not increase weight limits on Interstate Highways. In 1982, Congress passed the Surface Transportation Assistance Act (STAA), which imposed the Federal 80,000 lb. limit as a mandate across the entire Interstate Highway System. The STAA also contained significant provisions related to vehicle length as it applies to truck tractor-semitrailer and truck tractor-semitrailer-trailer combinations on the NN or in transit between NN highways and terminals or service locations.
These length provisions include the following:
- No State shall impose a length limitation of less than 48 feet on a semitrailer operating in a truck tractor-semitrailer combination.
- No State shall impose a length limitation of less than 28 feet on any semitrailer or trailer operating in a truck tractor-semitrailer-trailer combination.
- No State shall impose an overall length limitation on commercial vehicles operating in truck tractor-semitrailer or truck tractor-semitrailer-trailer combinations.
- No State shall prohibit commercial motor vehicles operating in truck tractor-semitrailer-trailer combinations.
- No State shall prohibit the operation of semitrailers or trailers which are 28 1/2 feet long when operating in a truck tractor-semitrailer-trailer combination if such a trailer or semitrailer was in actual and lawful operation on December 1, 1982, and such combination had an overall length not exceeding 65 feet.
- State maximum length limits for semitrailers operating in a truck tractor-semitrailer combination and semitrailers and trailers operating in a truck tractor-semitrailer-trailer combination are subject to the following:
- No State shall prohibit the use of trailers or semitrailers of such dimensions as those that were in actual and lawful use in such State on December 1, 1982, as set out in appendix B of 23 CFR 658.
If on December 1, 1982, State length limitations on a semitrailer were described in terms of the distance from the kingpin to rearmost axle, or end of semitrailer, the operation of any semitrailer that complies with that limitation must be allowed.
- No State shall prohibit the use of trailers or semitrailers of such dimensions as those that were in actual and lawful use in such State on December 1, 1982, as set out in appendix B of 23 CFR 658.
- No State shall impose a limit of less than 45 feet on the length of any bus on the NN.
Furthermore, STAA required States to allow these vehicles "reasonable access" to the NN, which includes Interstate highways and additional "Federal -Aid Primary" (FAP) roads that could safely accommodate STAA vehicles, later codified in 23 CFR 658, Appendix A.
The Federal vehicle size and weight standards listed in Exhibit 2 apply on NN highways. Some exceptions to Federal size and weight limits, known as "grandfather rights," were granted to States that allowed higher limits before imposing the STAA standards. Grandfather rights are discussed in more detail in a subsequent section.
| Overall Vehicle Length | No Federal length limit exists for most truck tractor-semitrailers operating on the NN. Exception: On the NN, combination vehicles (truck tractor plus semitrailer or trailer) designed and used specifically to carry automobiles or boats in specially designed racks may not exceed a maximum overall vehicle length of 65 feet, or 75 feet, depending on the type of connection between the tractor and the trailer (See 23 CFR 658.13 for more information). |
|---|---|
| Trailer Length | Federal law provides that no State may impose a length limit of less than 48 feet (or longer if provided for by grandfather rights) on a semitrailer operating in any truck tractor-semitrailer combination on the NN. (Note: A State may permit longer trailers to operate on its NN highways.) Similarly, Federal law provides that no State may impose a length limit of less than 28 feet on a semitrailer or trailer operating in a truck tractor-semitrailer-trailer (twin-trailer) combination on the NN. |
| Vehicle Width | On the NN, no State may impose a width limit of more than or less than 102 inches. Safety devices (e.g., mirrors, handholds) necessary for the safe and efficient operation of motor vehicles may not be included in the calculation of width. |
| Vehicle Height | No Federal vehicle height limit exists. State standards range from 13.6 feet to 14.6 feet. |
| Vehicle Weight | Federal weight standards apply to commercial vehicle operations only on the Interstate Highway System, which consists of approximately 50,000 miles of limited access, divided highways that span the Nation. Off the Interstate Highway System, States may set their own commercial vehicle weight standards. Federal standards for commercial vehicle maximum weights on the Interstate Highway System are as follows: Single Axle – 20,000 lbs.; Tandem Axle – 34,000 lbs.; GVW – 80,000 lbs. The Federal Bridge Formula, which was introduced in 1975 to reduce the risk of damage to highway bridges by requiring more axles, or a longer wheelbase to compensate for increased vehicle weight, may require a lower GVW; depending on the number and spacing of the axles in the combination vehicle. |
The Federal-Aid-Highway Amendments Act of 1974 and the Federal Bridge Formula
Bridge stress resulting from heavy trucks is influenced by several factors, including axle load, the total weight of the vehicle, and the distribution of the total load across the length of the vehicle (i.e., wheel base). The fatigue life of a bridge depends on the volume and magnitude of bending movements applied to a bridge from repetitive loadings. When heavy trucks cross a bridge, one or more stress cycles occur in the bridge components, which use up a portion of the components' fatigue lives.
As a result of the engineering axioms for pavement and bridge wear, the engineering community in the U.S. has set truck weight limits through laws and regulations that affect both axle loads and total weight of the vehicle.
The most well-known and most widely used formula in the U.S. for governing truck size and weight is the Federal Bridge Formula (FBF), also known as Bridge Formula B. The FBF was adopted by Congress when it passed the Federal -Aid-Highway Amendments Act of 1974 (and was signed into law by President Gerald Ford on January 4, 1975). As noted earlier, the 1974 law raised the Federal limit for single axles to 20,000 lbs., the tandem axle limit to 34,000 lbs., and the GVW limit to 80,000 lbs. The law also created a second grandfather exemption that allowed States to maintain weight tables or axle load limits that exceeded the newly established Federal limits.
The FBF uses the following equation: W=500 [LN/(N-1)+12N+36]
Where:
W= The overall gross weight on any group of two or more consecutive axles to the nearest 500 lbs.
L = The distance in feet between the outer axles of any group of two or more consecutive axles.
N =The number of axles in the group under consideration.
The FBF can be used to produce the weight table shown in Exhibit 3 on the following page. Regarding the FBF and Exhibit 3, it should be noted that:
- Pursuant to 23 CFR 650.313, all bridges must be inspected, rated to its safe load-carrying capacity, and if required, posted or restricted with respect to the maximum allowable weight.
- The Federal Bridge Formula Weight Table (Exhibit 3) paraphrases provisions of 23 U.S.C. § 127 and 23 C.F.R. 658 for purposes of illustration only. In the event of a dispute, the statute and regulation take precedence with respect to the Bridge Formula Weight Table (Exhibit 3).
Exhibit 3: Federal Bridge Formula Weight Table
Typical Truck Configurations
Commercial trucks can be defined and classified in many ways. The Federal Motor Carrier Safety Administration (FMCSA) defines commercial vehicles designed to carry freight as trucks with a GVW rating of 10,001 lbs. or more. The FHWA defines nine classes of vehicles designed to carry freight based primarily on the number of axles and whether the vehicle is a single unit truck or a combination vehicle (a power unit pulling one or more semitrailers or trailers). For the purposes of this report, we have chosen to describe the U.S. commercial truck fleet in terms of three primary types of vehicle configurations: 1) single-unit trucks; 2) combination trucks; and 3) longer combination vehicles (LCV).
Single Unit (SU) or Straight Trucks
Straight trucks refer to SU vehicles where the power unit and vehicle chassis are permanently attached. Straight trucks are popular vehicles for retail delivery (e.g., delivery vehicles, beverage trucks), construction (dump trucks, ready-mix concrete), and utilities and services (e.g., trash compactors, boom trucks, and snow plows). In 2012, SU trucks with six or more tires and a GVW rating of 10,001 lbs. or more accounted for 39 percent of the vehicle miles traveled by all commercial trucks with a GVW rating exceeding 10,000 lbs.6
Combination Trucks
Probably the most widely recognized commercial truck in the U.S. vehicle fleet is the five-axle tractor semitrailer vehicle, also known as the "18-wheeler." There are two variations in the power units or tractors: day cabs and sleeper cabs. Day cab tractors have a shorter wheelbase and are for pickup and delivery or other short haul operations. Sleeper cabs integrate a living area or a sleeping berth into the tractor. Sleeper cabs have an extended wheelbase, often 25 feet or more. Sleeper cabs are typically used for over-the-road or long-haul operations. The typical cargo carrying unit of a tractor-semitrailer combination can vary in length from 40 feet to 53 feet, with a few States allowing semitrailers up to 59 feet. A semitrailer attaches to the tractor by a kingpin to a fifth-wheel hitch mounted above the rear axles of the tractor. Combination trucks accounted for 61 percent of all commercial vehicle miles traveled in the United States in 2012 (includes miles traveled by LCVs).
Longer Combination Vehicles (LCVs)
The LCVs are a subset of combination vehicles that can only operate in certain States, where they are allowed to exceed 80,000 lbs. The LCVs are three- and four-vehicle combinations that use at least one full-length trailer in the combination (up to 48 ft.) or three shorter trailers. Three common LCV types are in operation across the United States:
- Rocky Mountain Doubles – a tractor with two trailers: a long front trailer (usually 48 ft.) followed by a shorter second trailer;
- Turnpike Doubles – a tractor and two long (usually 48 ft.) trailers; and,
- Triples – a tractor and three short trailers.
Exhibit 4 on the next page presents additional information about these common commercial truck configurations.
| Single-Unit (SU) Trucks – Also referred to as straight trucks, this class of vehicles includes all trucks on a single frame with two or more axles and dual rear wheels. These vehicles are allowed in all States, but the weight allowed depends on axle limits and axle spacing. All States must allow 20,000 per axle and 34,000 lbs. on a tandem axle on the Interstate Highway System. Due to grandfather provisions, 16 States allow higher axle limits on the Interstate; several more allow higher axle limits on non-Interstate highways through State statute. Many States provide exemptions for public vehicles like fire trucks, snow plows, and others. |  |
|---|---|
| Combination Trucks – These are commercial vehicles made up of two or more units, most commonly a tractor and a semitrailer. Double trailer combinations consisting of a tractor, a semitrailer, and a trailer are also common. The so-called STAA Double consists of a tractor and two trailers neither of which exceeds 28 feet in length. All of the vehicles in this group are allowed to travel the Interstate Highway System nationwide up to 80,000 lbs. The number of States that allow higher axle loads on Interstate and non-Interstate highways apply to combination vehicles as well. |  |
Longer Combination Vehicles – A subgroup of combination trucks, LCVs are double and triple trailer combinations that can exceed 80,000 lbs. on Interstate Highways in 23 States. All vehicles have seven or more axles consisting of three or more units, one of which is a tractor or a straight truck power unit. Three common LCVs are in operation across the U.S:
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Exemptions to Federal Weight Limits
Laws enacted in 1956, 1974, 1982, and 1991 form the basis for today's Federal requirement to regulate commercial vehicle size and weight on the U.S. Interstate System and the NN. The current Federal vehicle size and weight limits strive to strike a balance among ensuring the preservation of the road and bridge infrastructure on the highway network, safety, and vehicle productivity. These limits can only be changed through enactment of new statutory provisions.
To administer its vehicle size and weight oversight responsibility, the FHWA regularly monitors individual State enforcement of both Federal and State provisions through (1) the annual receipt of statutorily required reports and (2) by reviewing proposed legislation and other provisions that States may seek to change that could conflict with Federal statutory provisions. "Grandfather provisions" and exemptions add to the complexity of enforcing nationally uniform Federal weight limitations on the Interstate System. The discussion of grandfather provisions in the section that follows describes the size and weight allowances that exceed Federal standards on selected highways in the United States.
"Grandfather" Provisions
There are three different grandfather clauses in Title 23 USC§127. The first, enacted in 1956, deals principally with axle weights, gross weights, and permitting practices; the second, adopted in 1975, applies to bridge formula and axle spacing tables; and the third, enacted in 1991, ratifies State practices with respect to LCVs. The 1956 Federal-Aid Highway Act included a grandfather clause that applied only to State GVW limits that were already established and higher than the new Federal limit of 73,280 lbs. Previous studies of Federal truck size and weight issues have noted that regulatory limits, especially weight limits in place as of 1956, were often poorly recorded. Many States adopted liberal interpretations of State weight laws under grandfather provisions, arguing that trucks in their State should only be restricted to the weights that could have operated under the applicable special permit limits of 1956 and not just those weights that applied to regular operations (i.e., operating without a special permit).
The Federal-Aid Highway Amendments of 1974 adopted the FBF and raised the Federal limits on axle loads and GVW to the current standards. In passing the 1974 law, Congress also adopted a second grandfather clause that allowed States with weight tables or axle spacing formulas that exceed the Federal formula an exemption from the Federal formula/table. While the 1974 law raised weight limits, it did not mandate that States adopt the new limits.
In 1982 Congress passed the Surface Transportation Assistance Act of 1982 (STAA), which required States to adopt the Federal weight limits allowed in 1974 on all Interstate Highways. The STAA also established several minimum vehicle dimension provisions:
- States had to allow vehicles 102 inches wide on Interstate and other federally funded highway with 12 foot lanes;
- States had to allow combination vehicles with semitrailers up to 48 feet and could not prohibit the overall length of these combinations;
- States had to allow trailers up to 28 feet in twin trailer combinations; and
- States were prohibited from reducing trailer length limits that were in use and legal as of December 1, 1982.
The STAA also sought to resolve the grandfather controversy regarding States' claims of grandfathered weight limits based on pre-1956 permit practices. In doing so Congress granted to the States the ability to issue permits for vehicles and loads "which the State determines could be lawfully operated in 1956 or 1975."7
The Intermodal Surface Transportation Efficiency Act (ISTEA), Freeze
The Intermodal Surface Transportation Efficiency Act (ISTEA), passed in 1991, imposed a freeze on the weight of LCVs and limited their routes to those which were allowed by a State as of June 1, 1991. The ISTEA defined an LCV as, "any combination of a truck tractor or two or more trailers or semitrailers which operate on the National System of Interstate and Defense Highways with a GVW greater than 80,000 lbs." The ISTEA prohibits all States from expanding routes or removing restrictions on LCVs after June 1, 1991.
Each State was required to submit information on LCV requirements to the FHWA by December 1, 1991, to certify the size and weight restrictions that were in place before the freeze. The ISTEA allowed States to continue those LCV operations that were in actual and lawful operation in the State as of June 1, 1991, if the State so desired.
Longer Combination Vehicles are allowed in 23 States, but in six States they are allowed to operate only on turnpike facilities. The network routes on which LCVs can travel are described by State in 23 CFR 658, Appendix C. These routes are graphically displayed on the map in Exhibit 5.
Ultimately, most grandfather provisions and exceptions granted to States were codified in Federal law in Title 23 USC§127. The specific grandfather rights granted to States related to semitrailer length and to combination vehicles that exceed 80,000 lbs. have been adopted in 23 CFR §658, Appendices B and C, respectively. Federal laws that affect State exemptions/grandfather rights with regard to vehicle weights are summarized in Exhibit 6 below.
| Regulation | Weight Regulation |
|---|---|
| Federal-Aid Highway Act – 1956 | Interstate System:
|
| Federal-Aid Highway Act Amendments – 1974 | Interstate System:
|
| Surface Transportation Assistance Act (STAA) – 1982 | Interstate System: Mandated maximum limits on the Interstate, and made the previous single-and tandem-axle and GVW maximum the States could allow, the minimums they must allow on the Interstate highways. |
| Intermodal Surface Transportation Efficiency Act (ISTEA) – 1991 | Longer-Combination Vehicle (LCV) Freeze. |
When considered together, the successive grandfather provisions provided by Congress in 1956, 1974, and 1991 and other exceptions results in 37 States and the District of Columbia having allowances to exceed Federal weight limits on their Interstate highways (in many States these exceptions are very limited). The table in Appendix B of this report lists State exceptions to Federal weight limits. That table is derived from 23 CFR 658 Appendix C, which contains the weight and size provisions that were in effect on or before June 1, 1991 (July 6, 1991 for Alaska), for vehicles covered by 23 U.S.C. 127(d) (LCVs) and 49 U.S.C. app. 2311(j) (commercial motor vehicles [CMVs] with two or more cargo-carrying units). The table also includes State exceptions to Federal limits on the Interstate System based on grandfather provisions and exceptions codified in Title 23 U.S.C.§127. It should be noted for those States that have claimed general exceptions to Federal limits on Interstate highways (such as higher single or tandem axle limits); these higher limits also apply to non-Interstate elements of the NHS. It should also be noted that in accordance with Title 23 U.S.C.§127 States can seek to establish grandfather rights at any time if the State determines a vehicle could be lawfully operated within such State on July 1, 1956, except in the case of the overall gross weight of any group of two or more consecutive axles, on the date of enactment of the Federal-Aid Highway Amendments of 1974.
1 Definition taken from FHWA web page: https://www.fhwa.dot.gov/planning/national_highway_system/ [ Return to note 1. ]
2 Definition taken from FHWA web page: http://ops.fhwa.dot.gov/freight/infrastructure/national_network.htm [ Return to note 2. ]
3 State profiles for North Dakota and South Dakota were not validated by State agency representatives; however, National Conference of State Legislatures (NCSL) reviewed the profiles to verify the completeness, accuracy, and timeliness. [ Return to note 3. ]
4 States are subject to the standard Federal weight limits for Interstate highways (20,000 lbs. on a single axle, 34,000 lbs. on a tandem axle and 80,000 lbs. gross vehicle weight) unless there are State-specific grandfathered limits or exceptions to these limits. On the NN, no State may impose a width limitation of more or less than 102 inches. Safety devices (e.g., mirrors, handholds) necessary for the safe and efficient operation of motor vehicles may not be included in the calculation of width. [ Return to note 4. ]
5 USDOT Comprehensive Truck Size and Weight Study, Volume 2, "Chapter 2: Truck Size and Weight Limits – Evolution and Context," FHWA-PL-00-029 (Washington, DC: FHWA, 2000), p. II-9. [ Return to note 5. ]
6 USDOT, FHWA, Highway Statistics 2012, Table VM-1, January 2014. Online version: https://www.fhwa.dot.gov/policyinformation/statistics/2012/vm1.cfm [ Return to note 6. ]
7 Transportation Research Board, Committee for the Truck Weight Study, Special Report 225, Truck Weight Limits: Issues and Options, (Washington, D.C.: TRB, 1990). [ Return to note 7. ]
8 U.S. Department of Transportation, Federal Highway Administration, Office of Freight Management and Operations, 2013. [ Return to note 8. ]
9 USDOT, Comprehensive Truck Size and Weight Study, FHWA-PL-00-029 (Washington, DC: FHWA, 2000). Available at: https://www.fhwa.dot.gov/reports/tswstudy/ [ Return to note 9. ]
