Highway Statistics 2021
This publication brings together an annual series of selected statistical tabulations relating to highway transportation in twelve major areas: (1) Bridges; (2) Highway Infrastructure; (3) Highway Travel; (4) Travelers (or System Users); (5) Vehicles; (6) Motor Fuel; (7) Revenue; (8) Debt Obligation for Highways; (9) Apportionments, Obligations, and Expenditures; (10) Conditions and Safety; (11) Performance Indicators; and (12) International.
Please note that tables marked with an asterisk in the Table of Contents are only available at our Internet website for viewing/downloading at www.fhwa.dot.gov/policyinformation/. (See Highway Statistics Series publications).
The vast majority of highway data are submitted by the States. Each State is analyzed for consistency against its own past years of data and also against other State and Federal data. Major issues are resolved with the help of the data provider. The cooperation of Federal, State, and local agencies in providing the basic data from which these statistical series are derived is acknowledged and greatly appreciated.
While the Office of Highway Policy Information is responsible for the preparation of this publication, a number of the statistical summaries are prepared by other units with the Federal Highway Administration (FHWA) as indicated by notes on the tables involved.
Responsibility for administering the highway network of the United States, providing funds for its continued improvement and maintenance, and regulating its use is a complex affair involving Federal and State agencies, together with nearly 39,000 county, township, and municipal governments and, to a limited degree, the private sector. These agencies work in concert in many ways in the management of the Nation's highway assets.
Periodically, the Congress passes legislation authorizing the spending of federal funds for highway purposes. The legislation also provides for revenue sources in the form of highway taxes to fund these expenditures. The legislation provides the guiding principles and funding programs to address highway national transportation requirements and to direct funding to address issues such as highway safety. The federal emphasis is on the capital improvement of high capacity highways that carry the bulk of the passengers and freight movement in interstate commerce. The federal legislation supports the States funding of their own highway programs, and these cooperative efforts result in the development and maintenance of the national highway system.
The FHWA is the principal highway agency of the Federal Government. Under the Federal-aid highway program, the initiative for selecting routes eligible for improvement with Federal-aid funds rests with the States. These routes remain under the ownership of the State or local governments which are responsible for administering and maintaining them as part of the State or local highway systems.
The FHWA also administers the Federal Lands Highways Program. This program is funded from the Federal Highway Trust Fund and consists of three separate programs: Park Roads and Parkways, Indian Reservation Roads, and Public Lands Highways. The Department of Defense provides funds for the construction of roads leading to military installations, etc., but these funds are usually transferred to the FHWA to manage the construction program.
Some Federal agencies also provide funds for road and bridge work which is incidental to their major functions. For example, the Corps of Engineers (Department of the Army) and the Bureau of Reclamation (Department of the Interior) expend funds for highway and bridge construction and reconstruction on projects involving water resources and navigable rivers. Other Federal agencies, such as the Forest Service, provide funds through a policy of sharing with States and counties some of the income derived from timber sales on Federal lands, a portion of which is placed in road funds.
Additional Federal funds are provided from the General Treasury to States, counties, and cities through the programs of other Federal agencies such as Urban Development Block Grants for various purposes including highways. The different Federal assistance programs for highway are summarized in the latest version of the FHWA publication, Highway Taxes and Fees, How They Are Collected and Distributed, Table F-106.
The Treasury Department's Internal Revenue Service collects the Federal road-user taxes and deposits the revenues in the Federal Highway Trust Fund. Amounts dedicated by Congress for mass transportation are credited to a separate mass transit account.
In the Federal Highway Administration's financial analyses, special State commissions and authorities, toll and non-toll, as well as State highway and transportation departments, are classified as "Other State". Other executive branches of State governments also have been included when, and to the extent, they are responsible for the collection and distribution of road-user taxes or perform highway and related functions. Examples of these executive agencies are treasury and revenue departments, motor-vehicle departments, public-safety departments (highway police and low enforcement activities), and conservation departments when they are responsible for roads within State parks, forests, or reservations. The District of Columbia is treated as a State.
Local governments include: counties, townships, and municipalities. Included with local governments are subordinate agencies, road districts, commissions, and authorities, both toll and non-toll. All States have organized county governments except Connecticut and Rhode Island. Counties, however, have limited or no responsibility for roads in the New England States, or in Delaware, North Carolina, Virginia (with some exceptions), and West Virginia. In Alabama and Maryland, the State has assumed responsibility for roads in certain counties. Counties are called parishes in Louisiana, boroughs in Alaska, "municipios" in Puerto Rico, and townships are towns in New England, New York, and Wisconsin.
A municipality is a political subdivision where a municipal corporation has been established to provide general local government for a specific population concentration in a specified area. Some counties have boundaries coextensive with cities. Generally, these counties retain their identities only for certain administrative purposes. Because some counties are entirely urban in nature or have merged with municipalities, they are classified as municipalities. A county may also be classified as a municipality when its area consists predominantly of incorporated cities, towns, and villages. Although generally considered to be rural governments, many townships, particularly in the Northeast, serve heavily populated areas and perform the functions of a municipal government.
The term "urban" is used in these summary tables is consistent with the Federal-aid legislation definition of an area. Such areas include, at a minimum, a census place with an urban population of 5,000 to 49,999 or a designated urbanized area with a population of 50,000 or more (or portions thereof within State boundaries). The Federal-aid boundaries are determined by responsible State and local officials, subject to the approval of the Secretary of Transportation. These Federal-aid urban areas may extend beyond incorporated (with some exceptions) and census boundaries, and thus are not necessarily coextensive with municipal boundaries.
Individual Unit Statistics
In general, the statistical series present summary data primarily on a State-by-State basis. However, in the highway finance sections, special tabulations are included for individual toll authorities. The roadway extent section includes two tables detailing information for urbanized areas. Inquiries for information on a county-by-county basis should be directed to the respective State highway agencies.
Users of these data must be careful to avoid "double counting" of the statistical data that could result from the effect of intergovernmental relationships. This is particularly so with reference to tables in the finance and mileage sections, because of the overlapping of Federal-aid activities with the State and local highway activities, and the effects of grant-in-aid programs. Examples are Federal-aid payments, which are in turn reported as State receipts and included in State expenditures; and Federal-aid highway system mileage, which are parts of the State and/or local highway systems, and are also included in those systems. Summary tables that give national statistics have been included at the beginning of the finance and mileage sections, and eliminate "double counting" or duplication. These are then followed by table series that reflect the transactions of each level of government, but which are not necessarily cumulative to national totals.
The Highway Performance Monitoring System (HPMS) is an annual compilation of data about the state of the Nation's highway system. Information included in the HPMS database is the result of a cooperative effort between the FHWA and State and local governments. All HPMS data are provided to the FHWA through State Departments of Transportation and are usually obtained from existing State or local government databases, including those of Metropolitan Planning Organizations (MPOs). Typically, the existing databases and record keeping systems of State and local governmental units are designed and maintained to meet their specific, individual business needs; most items in their databases are not specifically designed to meet Federal reporting purposes. Some data required for the HPMS are not collected by all the States for their own databases; some State adjustments to State collected data may have been made in order to meet the requirements of the HPMS.
As a result, data quality and consistency of HPMS information are dependent upon the programs, actions and maintenance of sound databases by numerous data collectors, suppliers and analysts at the State, metropolitan, and other local area levels. In general, specific data items that are used by the collecting agency are likely to be of better quality than data items that are collected or estimated solely for the use of the FHWA. Data quality and consistency are also dependent upon the nature of the individual data items and how difficult they are to define, collect, or estimate.
HPMS data are collected in accordance with the HPMS Field Manual. This document contains standard collection, coding, and reporting instructions for the various data items to be reported with the objective of creating a uniform and consistent database. The degree to which these instructions are followed by the reporting agencies has a direct impact on the quality and consistency of the data and, therefore, on the utility of these data as an indicator of the condition, performance, and use of the Nation's highway systems. State reported HPMS data are reviewed by FHWA for completeness, consistency, and adherence to reporting guidelines. Data are generally used as reported; any adjustments are accomplished in close working relationship with data providers.
The HPMS database is constructed primarily to facilitate national level analyses of the condition, performance, and use of the Nation's highway system. Users of the HPMS data, as reported in Highway Statistics and in other media, should not necessarily expect to find consistency among all States for all data items, due to State-to-State differences in the way the data are defined, collected, or estimated. Even when data are consistently collected and reported, users need to recognize that HPMS information may not be comparable across all States due to inherent State differences such as size, population density, degree of urbanization, extent of system, administrative responsibility, climate, etc. When making State level comparisons, therefore, it is inappropriate to use these statistics without recognizing and accounting for the differences that may impact comparability.
This section contains a series of six tables from the FHWA Office of Bridge Technology in the FHWA Office of Infrastructure. While FHWA has published these tables in Highway Statistics to provide a broader perspective of the complete highway infrastructure, for further information we recommend the reader to go to the Bridge technology website at the URL: https://www.fhwa.dot.gov/bridge/.
This section contains data on the physical extent and ownership of public roads in the United States. Public roads include those that are open to public travel and maintained by a public authority – see Code of Federal Regulations (23 CFR 460). Other roads and trails that are privately owned, not publicly maintained, or restricted from use by the general public are excluded.
Public Road Length Data
All length tables in this section, except table HM-30, reflect the centerline length of public roads. Except for minor amounts of Federal public road length under the U.S. Forest Service, Bureau of Reclamation, Bureau of Indian Affairs, National Park Service, Fish and Wildlife Service, and military, the rest of the public roads in the United States are owned by State, county, town, township, Indian tribe, municipal or other local governments, or instrumentalities thereof. Public roads in Federal forests and reservations may be part of the State and local road systems and are included with the lengths reported for those systems.
Federal-aid Highway Data
Federal-aid highways are segments of State and local road systems eligible for Federal-aid construction and rehabilitation funds because of their service value and importance. Except for connectors on the National Highway System (NHS), roads that are functionally classified as rural minor collector or rural or urban local are excluded. The designation of a public road as a Federal-aid highway does not alter its ownership as a State, county, or city street.
The Dwight D. Eisenhower National System of Interstate and Defense Highways was originally established by the Federal-Aid Highway Act of 1944. The Federal-Aid Highway Act of 1956 and the companion Highway Revenue Act of 1956 further defined the purpose and extent of the system and, as subsequently amended, dedicated several Federal excise taxes on motor fuel and automotive products to support Federal-aid highway activities. The Interstate System extends over 46,000 miles (74,000 kilometers) and connects, as directly as practicable, the Nation's principal metropolitan areas, cities, and industrial centers; serves the National defense; and connects at suitable border points with routes of continental importance.
National Highway System
The Intermodal Surface Transportation Efficiency Act (ISTEA) of 1991 eliminated the historic Federal-aid systems and created the National Highway System and other Federal-aid highway categories. The NHS was selected in consultation with appropriate State and local officials; it consists of the highway routes and connections to transportation facilities depicted on the maps submitted by the Secretary of Transportation to the Congress on May 24, 1996 and approved by the National Highway System Designation Act of 1995. Highways designated as part of the Interstate System are included in the NHS. Non-roadway routes, such as ferry boats, are not included in Highway Statistics.
Functional System Data
The functional systems used in tables HM-50 through HM-80 result from the grouping of public roads according to the character of service they are intended to provide. Because most travel involves movement through a network of roads, individual public roads do not serve travel independently in any major way. Functional classification defines the role that a particular public road plays in serving the flow of trips through a highway network. The functional systems are: (1) arterial highways, which generally handle the long trips; (2) collector facilities, which collect and disperse traffic between the arterials and the lower level roads; and (3) local roads, streets, and other public ways, which serve a land access function to homes, businesses, individual farms and ranches, and other uses. Road length by functional system is identified by ownership, surface type, lane width, traffic lanes, access control, and traffic volume in Tables HM-50 through HM-59.
The number of through traffic lanes as reported by the States are used to calculate lane length for all roads on the NHS or functionally classified above rural minor collector or urban local. Starting in 1999, number of lanes was required for all functional systems except the rural minor collector and the rural /urban local systems, and for all NHS routes; lane length is computed on a 100-percent basis. For these systems, Lane-miles is calculated by multiplying the number of through lanes on a given roadway section by its centerline length. For the rural minor collector and the rural/urban local functional systems, the number of through lanes is assumed to be two; lane length is the product of the functional system centerline length times two.
The surface classification identifies the pavement type used on the traveled portion of the roadway. Many highways, either by original design or because of reconstruction, consist of more than one major type of construction material. No data relative to vertical composition are presented, although material and layer thickness criteria are used to define the reporting categories.
The FHWA uses daily vehicle-miles of travel (DVMT) [daily vehicle-kilometers of travel (DVKT)] as the primary measure of travel activity on the Nation's highway systems. The daily travel times 365 days (366 days for leap years) equals annual travel.
Travel is a calculated product of the annual average daily traffic (AADT) and the centerline length of the section for which the AADT is reported. In the HPMS, travel is accumulated for each universe section to develop appropriate totals for the higher functional systems. AADT is required for each section of Interstate, NHS, and other principal arterial; as a result, travel is computed for these functional systems on a 100-percent basis. For minor arterial, rural major collector and urban collector systems, travel is calculated from samples using the AADT, centerline length reported for each sample section, and the HPMS sample expansion factor for each section. Travel for the NHS on all functional systems is computed from the universe AADT data.
For the most part, travel for the rural minor collector and rural/urban local functional systems are calculated by the States using their own procedures and are provided in HPMS on a summary basis. Some States use supplemental traffic counts outside of the HPMS procedures; others employ estimating techniques, such as fuel use, to determine travel on these systems. In general, these methods are used in both rural and urban areas, including the donut areas of designated air quality non-attainment areas to meet traffic monitoring requirements of the Clean Air Act.
AADT and travel estimates are edited by the HPMS software and reviewed by FHWA for unusual values and for unusual changes to previously reported values. FHWA works with State data providers to ensure that reported AADT values are reasonable before final use. Although AADT is required to be updated annually in HPMS, counts are required to be taken only on a 3-year cycle. Usually, AADT for uncounted sections are estimated by modeling the latest year's count. States that follow the HPMS sampling instructions in developing traffic counting programs (Appendix F in the HPMS Field Manual) and the practices advocated in the Traffic Monitoring Guide have adequate counting and classification tools to prepare quality AADT and travel estimates for HPMS. These procedures should also provide comparable State-to-State traffic data.
Table VM-1 is a summary of estimated travel by vehicle type and system; total travel values are derived from the highway functional system data contained in table VM-2, while the vehicle type breakdowns are derived from the HPMS summary data. The other rural arterial roads category includes the other principal and minor arterial functional systems; and the other rural roads category includes the collector and local functional systems. All urban systems, except the urban Interstate System, are included in the other urban public roads category.
The highway use of motor fuel and the motor vehicle registrations from tables MF-21 and MV-1 are used to estimate average distance traveled per vehicle, average fuel consumed per vehicle, and average distance traveled per gallon of fuel consumed. The estimate of distance traveled per person is based on the most current information from the Nationwide Personal Transportation Survey, the Truck Inventory and Use Survey, and the National Transportation Statistics report. Note that the number of decimal places corresponds to the control totals in the final column, not the level of precision.
Table VM-2 is a summary of the States' estimated highway travel based on traffic counts by functional system; it is a companion to table HM-20. Table VM-3 contains estimated highway travel on Federal aid highways; it is a companion to length table HM-15. Table TC-3 presents a distribution of historic Interstate System traffic volumes and loadings; it shows the interrelationship among vehicle types, volumes, and axle loadings. The data, which are from the Truck Weight Study, are collected by the States from weigh-in-motion systems. The accompanying graph, "Comparison of Growth in Volumes and Loadings on the Rural Interstate System", shows the growth in loadings relative to volumes. The data points on the graph are 3-year moving averages.
HPMS data are collected in accordance with the Highway Performance Monitoring System Field Manual (Field Manual).
Travelers (or System Users)
Each State and the District of Columbia administers its own driver licensing system. Since 1954, all States have required drivers to be licensed, and since 1959 all States have required examination prior to licensing. Tests of knowledge of State driving laws and practices, vision, and driving proficiency are now required for new licensees. The American Association of Motor Vehicle Administrators (AAMVA) has compiled the Fast Track to Vehicle Services Facts, a motor vehicle regulations and procedures information guide with information provided by United States and Canadian jurisdictions. Also, the AAMVA Knowledge Bank provides access to sets of comparative data that have been collected from the jurisdictions. To contact AAMVA, call 703-522-4200 or 4301 Wilson Boulevard, Suite 400, Arlington, VA 22203.
Since there will always be persons of driving age who will not be licensed, by choice or because of physical or mental infirmities, the ratio of licensed drivers to total population should never reach 1.0 (or 100 percent). However the following conditions can make the relationships higher than expected:
- Although efforts are made to minimize it, drivers who move from one State to another are sometimes counted in both States until the license from the previous State of residence expires.
- Some persons obtain their driver licenses in States other than those of legal residence.
- Some persons fraudulently obtain multiple licenses. Some State authorities doubt whether all persons who drive are licensed. Where this problem exists, those that are unlicensed would partially offset any duplicate licenses issued and inactive licenses. The degree to which this occurs is unknown.
- The purging of expired licenses or licenses from deceased persons is not done on a continual basis.
Use of Data
Since State drivers license laws changed significantly in recent years, especially in the area of teenage drivers, FHWA changed its definition for teenage drivers to reflect more accurately the actual number of teens driving beginning with Highway Statistics, 2006 data. Therefore, States should report drivers 16-years old and under.
The vehicle registration practices vary widely among the States. Although many States continue to register specific vehicle types on a calendar year basis, all States use some form of the "staggered" system to register motor vehicles. The "staggered" system permits a distribution of the renewal workload throughout all months. Most States allow pre-registration or permit "grace periods" to better distribute the annual registration workload.
In order to present vehicle registration data uniformly for all States, the information is shown as nearly as possible on a calendar-year basis. Insofar as possible, the registrations reported exclude transfers and re-registrations and any other factors that could otherwise result in duplication in the vehicle counts.
Registration practices for commercial vehicles differ greatly among the States. Some States register a tractor-semitrailer combination as a single unit; others register the tractor and the semitrailer separately. Regardless of how they were registered, only the power units have been included in the truck count in table MV-1. Some States register buses with trucks or automobiles; many States do not report house and light utility trailers separately from commercial trailers or semitrailers; and some States do not require registration of car-sized or light utility trailers. To account for the variations in State practice, FHWA has supplemented the data provided by the States with information obtained from other sources.
Motor vehicle registrations are reported by major vehicle classes: automobiles, buses, trucks, and motorcycles. The truck category includes light trucks to the extent they can be identified and separated from automobiles. Data on trucks, buses, trailers, and semitrailers are given in tables MV-9, MV-10, and MV-11, respectively. Although the detail of motor-vehicle data has improved in recent years, it is not yet possible to obtain from all States separate data on single-unit trucks and combinations. Some States provide data for light trucks and truck tractors, but for many States, the FHWA estimates this information using other data sources, such as the Truck Inventory and Use Survey conducted by the Bureau of the Census. The table MV-9 light truck category includes pickups, vans (full-size and mini), utility-type vehicles, as well as other vehicles (panel trucks and delivery vans generally of 10,000 pounds or less gross vehicle weight). Registrations of publicly owned motor vehicles are reported in table MV-7.
Registration Taxes and Fees
Taxes and fees connected with State motor-vehicle registrations and special taxes on motor carriers are given in table MV-2, and the disposition of these taxes is given in table MV-3. The diversity of taxes and fees collected has made it necessary to group them into broad general classes, the most important being registration fees. The amounts shown are those collected solely as highway-user revenues and do not include any amounts, such as personal property levies, that are derived from taxes other than those related to motor-vehicle ownership and operation. (Although portions of these revenues are later used in some States for non-highway purposes, it is the source rather than the expenditure of the revenues that has determined their inclusion here). Motor-vehicle registration fee schedules (table MV-103) and administrative provisions governing the disposition of State motor-vehicle and motor-carrier receipts (table MV-106) appear in a separate FHWA publication entitled Highway Taxes and Fees, How They Are Collected and Distributed.
Use of Data
All State reported data are analyzed by FHWA for completeness, reasonableness, consistency, and compliance with data reporting instructions contained in A Guide to Reporting Highway Statistics. State reported data is adjusted if necessary to eliminate mistakes and to improve data uniformity among the States. The analysis and adjustment process is accomplished in cooperation with the States supplying the data. In some instances, corrections or revisions have been made in previously published data. Data is updated as needed, and the most recent is reflected on the Highway Statistics Series webpage.
In addition, FHWA and the National Highway Traffic and Safety Administration (NHTSA) use different registration data sources and different vehicle definitions. FHWA requests that it be provided data specifically identifying the various types of passenger-carrying highway vehicles. For example, the State reported data should specify if passenger vans have been reported as passenger vehicles or light trucks. While a State may report minivans, station wagons on truck chassis, and utility-type vehicles as passenger cars to FHWA, these vehicles are considered as trucks in both the FHWA and NHTSA data series.
The FHWA data includes all vehicles that have been registered at any time throughout the calendar year. Data includes vehicles that were retired during the year and vehicles that were registered in more than one State. In some States, it is also possible - contrary to the FHWA reporting instructions – that vehicles that have been registered twice in the same State may be reported as two vehicles. The NHTSA data includes only those vehicles that are registered as of July 1 of the given year. Therefore, they do not include vehicles registered in the last half of the calendar year or vehicles that may only be registered for a part of a year such as those for farm use.
Each State and the District of Columbia administers its own driver licensing system. Since 1954, all States have required drivers to be licensed, and since 1959 all States have required examination prior to licensing. Tests of knowledge of State driving laws and practices, vision, and driving proficiency are now required for new licensees. The summary of State driver licensing requirements has previously been in a separate biennial publication, Driver License Administration Requirements and Fees. The American Association of Motor Vehicle Administrators (AAMVA) has combined this publication with a companion publication by the National Highway Traffic Safety Administration entitled State and Provincial Licensing System Comparative Data (December 1999). The combination of these two reports will eliminate any duplication in effort and give you all information pertinent to obtaining an operator or commercial license in any State or of Canada. To order a copy of this report, call AAMVA at 703-522-1300 or Fax your request to 703-522-1553.
The tables in this section show the volume of motor fuel used for highway and non-highway purposes. The following types of fuel are included: gasoline, gasohol, diesel, kerosene, liquefied petroleum gas (propane), liquefied natural gas, compressed natural gas, E85, and M85. Gasohol, a blend of gasoline and fuel alcohol of 10 percent or less, is included with gasoline in all motor fuel tables in this section. All the other fuel types listed are combined into one category called special fuels.
The records of State agencies that administer the State taxes on motor fuel are the underlying source for most of the data presented in these tables. When reporting gasoline and gasohol, States are to report all uses of those fuels. When reporting all the special fuels, States are to only report on-highway fuel uses. The FHWA estimates highway use of gasoline by subtracting estimated non highway use from the total use reported by the States.
Over the last several years, there have been numerous changes in State fuel tax laws and procedures that have resulted in improved fuel tax compliance, especially for diesel fuel. The improved compliance has resulted in increased fuel volumes being reported by the States to FHWA. The trends shown in the tables reflect both improvements in tax compliance and changes in consumption.
Motor Fuel Use
Analyses of motor fuel consumption are given in tables MF-21 and MF-24. These tables do not include data on fuel purchased by the Federal Government for military use or fuel exported from the United States. In table MF-21, adjustments have been made to allow for losses from destruction, evaporation, spillage, etc. Additional detail has been added to table MF-21 so that consumption is completely cross-classified by type of highway or non-highway use.
Table MF-33GA shows, by month, gross gasoline volumes, which have been reported in the publication entitled: Monthly Motor Fuel Reported by States. Since the data in this table are taken from monthly reports issued by State fuel-tax agencies, and few year-end adjustments have been made, the totals will not agree with those shown in table MF-21. Adjustments are made in the annual data to exclude percentage losses in excess of 1 percent and to reflect usage rather than tax collections. MF-33SF table shows the same information for special fuels.
State Motor Fuel Taxation
The volume of motor fuel exempt from and subject to State taxation is shown in table MF-2. This table is intended for use in revenue analyses and shows fuel volumes without regard to the type of use. The motor fuel tax collections for all States are given in table MF-1, and the disposition of these revenues is given in table MF-3. In most States, the tax on aviation fuel is either refunded or placed in a special fund for aviation purposes. Similarly, some States place in a separate fund all or part of the tax paid on fuel used by marine craft and use these funds for the improvement of marine facilities. When revenue from fuels used for non-highway purposes is dedicated for expenditure for specific non-highway purposes, it is shown in column 6 of table MF-1. Table MF-3 shows the disposition of the highway user revenues shown in column 7of table MF-1.
Federal tax rates in effect for the latest calendar year for gasoline and other motor fuels are given in table FE-21B. State tax rates in effect for the latest calendar year for gasoline and other motor fuels are given in table MF-121T.
The words "exemption" and "refund" are not used interchangeably. In this publication, exemption is applied when the State purposely did not collect the tax; refund is applied when the State collected the tax and later returned it, in whole or in part. Exemptions are most frequently granted on motor fuel purchased by the Federal Government; they are also granted as allowances for loss through evaporation, spillage, etc. Refunds are often granted for non-highway uses of motor fuel such as for agriculture, aviation, manufacturing, construction, and marine purposes. In most States, gasoline used for non-highway purposes is taxed but the tax is refundable, but special fuels used for non-highway purposes are exempt from taxation. Historical data on State and Federal motor fuel gasoline and diesel taxes are included as table MF-205. Historical data on Federal motor fuel and related taxes can be found in tables FE-101A and FE-101B.
A separate publication entitled Highway Taxes and Fees, How They Are Collected and Distributed provides additional information on motor fuel.
Since September 30, 1996, all States (except Alaska and Hawaii) and most Canadian Provinces have been participating members in the International Fuel Tax Agreement (IFTA). IFTA replaced individual State motor-fuel tax provisions on Interstate motor carriers with a uniform method of reconciling motor-carrier taxation among member jurisdictions. The uniform method simplified motor-fuel tax reporting by allowing a motor carrier to report and pay motor-fuel taxes owed to the States and Canadian Provinces to a single base jurisdiction, typically their home State or Province. Under IFTA an Interstate motor carrier only needs a single IFTA fuel tax license for each of its qualified motor vehicles. The base State or Province uses a clearinghouse arrangement to forward the portion of motor-fuel taxes owed to other member States and Provinces. Payments for qualified motor vehicle are made quarterly in all jurisdictions.
The tables in this section show highway receipts, revenue, and other financial information of Federal, State, and local governments. Note that highway finance data for local governments are collected every other year, and therefore some tables may display data for the previous year.
The first tables in this section give combined summaries of highway finances for all levels of government. The summary tables are followed by specialized tables showing Federal, State, and local government data separately. While intergovernmental transfers have been eliminated from the summary tables, the specialized tables are not additive without appropriate adjustments for intergovernmental payments. For example, Federal payments to States for highways are reported as an expenditure on the Federal tables, while the States' expenditures of those funds are reported as expenditures on the State finance tables.
Table HF-10 combines, for all levels of government, receipts and disbursements for highways (with local government data and some Federal data estimated). Table HF-10 also includes information on gross collections and disposition of highway-user revenue and identifies intergovernmental payments by level of government. Table HDF presents total collections of highway-user imposts and distributions of highway-user revenue to highway and other purposes by State. Tables HF-1 and HF-2 eliminate intergovernmental payments and summarize total receipts and disbursements for highways by State for the previous year, the latest year that finance data for all levels of government are available. Table HB-2 summarizes the highway debt status of State and local governments.
The Federal-aid highway program is financed from the proceeds of motor-fuel and other highway-related excise taxes deposited in the Federal Highway Trust Fund (HTF). The Federal-aid highway program is a federally assisted, State-administered program which distributes Federal funds to the States for the construction and improvement of urban and rural highway systems. On Federal-aid highway projects, a State develops the plans, lets the contracts, and supervises the construction. The roads remain under the administrative control of the State or local government responsible for their operation and maintenance.
Evolution of the Federal-aid Program
Although Federal aid for highways began in the late 1800's, Federal assistance was not provided uniformly to all States with the purpose of developing an integrated network of highways until 1916. In 1921, Federal aid was restricted to a limited connected system of principal roads which became the Federal-aid Primary Highway System. Provision was made in 1944 for the designation of a Federal-aid Secondary System of principal farm-to-market and feeder roads. Also in 1944, for the first time, specific authorization of Federal-aid funds was made for urban extensions of the Primary System, and in 1954, for urban extensions of the Secondary System. In 1973, funding for a separate Urban System program was established. Part of the authorized funding was specifically earmarked for urbanized areas with a population of 200,000 or more.
Planning began in the late 1930's for what became the Eisenhower System of Interstate Defense Highways. Although a system of highways was identified in 1944, only modest funds were provided prior to 1956. The Federal-aid Highway Act of 1956, as subsequently amended, increased and provided funding on a 90-percent Federal, 10-percent State matching basis, and made the Eisenhower System of Interstate and Defense Highways a dominant feature of the Federal-aid Highway Program. Subsequent legislation has extended the Interstate authorizations until 1995, after which the Interstate system and its funding was incorporated into the NHS program or the Interstate Maintenance (IM) program.
In recent years, increased attention has been directed to the preservation and reconstruction of the Nation's highways and bridges. Although regular Federal-aid funds may be used by the States for the rehabilitation and replacement of deficient bridges, a special bridge rehabilitation and replacement program with separate authorizations began in 1970.
Beginning in 1976, a special category of Interstate funds was specifically authorized for resurfacing, restoration, and rehabilitation (3R) work. In 1981, the program was amended to include reconstruction (4R) and funding was substantially increased. Under the Inter-modal Surface Transportation Efficiency Act of 1991 (ISTEA), resurfacing, restoration and rehabilitation are funded under the Interstate Maintenance (IM) program. The Federal share of IM projects is generally 90 percent. The ISTEA eliminated the historical Federal-aid system designations of Primary, Secondary, and Urban, and it created the National Highway System (NHS). The NHS includes the Interstate System routes, a large percentage of urban and rural principal arterials, the Strategic Highway Network, and major connectors. The ISTEA also created a new flexible funding program, the Surface Transportation Program (STP), that can be used for roads and streets not functionally classified as local or rural minor collector, for bridges on any public road, and for transit capital projects. The Transportation Equity Act for the 21st Century (TEA-21), PL 105-178, enacted June 9, 1998, extended the ISTEA program structure through Fiscal Year 2003.
The Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU), Public Law 109-59, enacted August 10, 2005, was the principal Federal legislation that authorized Federal highway programs for Fiscal Year 2005-2009. Currently, Congress is considering another highway authorizing bill.
The Federal Highway Trust Fund
The Federal HTF is the funding source for the Federal-aid highway program. The HTF was established by the Highway Revenue Act of 1956. Changes in the Federal excise tax structure have occurred periodically. Tables FE-101A and FE-101B provide a historical summary of Federal excise tax rates, including rates currently in effect. Table FE-21B provides additional detail on Federal motor-fuel taxes.
Effective April 1983, the Highway Revenue Act of 1982 created the Mass Transit Account within the HTF. The Act provided that the equivalent of one cent per gallon of the motor-fuel taxes would be deposited in the Mass Transit Account for transit system capital expenditures. Tables FE-101A and FE-21B trace the history of the taxes dedicated to the Mass Transit Account.
Federal HTF revenues are derived from various Federal excise taxes on highway users. The attribution of these revenues to highway users in each State is shown in table FE-9. Since these revenues cannot be directly related to payments by highway users in each State, the receipts attributable to highway users in each State are estimated by the FHWA based on highway fuel consumption.
Table FE-221 shows a comparison, by State, of HTF Highway Account receipts attributable to highway users and apportionments and allocations from the Fund. This table reflects a concerted effort to include all funds apportioned or allocated to the States from the Highway Account in the HTF. Table MF-27 shows the previous year's highway motor fuel gallonage used to attribute the current data year HTF receipts to the States in table FE-221.
The SF and SB table series show the highway finance activities and debt status of State highway agencies. Table SF-21 consolidates and summarizes all highway receipts and disbursements of the States. The remaining tables in the SF series provide further details and breakdowns of all highway receipts and disbursements of the States, including data on State toll facilities.
State aid to local governments
States provide assistance to the highway, road, and street programs of local governments primarily through the transfer or sharing of highway-user revenue. However, State aid is not limited to highway-user revenue. Many States also transfer other State revenues or redistribute Federal funds to local governments. Some States also perform a significant amount of work on roads and streets under the jurisdiction of local governments. For uniformity in FHWA analyses, all State-imposed taxes and fees on highway-users are considered to be collected and distributed by the States. The local governments' share of State highway-user revenue, if any, are shown as intergovernmental payments from the State.
Many local governments collect State motor-vehicle taxes and retain a portion before forwarding the remaining receipts to the State. The retained amounts are also shown as a State intergovernmental payment to local governments. In 2001, the statutes of 47 States provided for the sharing of State-collected highway-user tax revenue with local governments for road and street purposes. This assistance is in the form of direct grants-in-aid and shared revenue. Georgia, Rhode Island, and West Virginia did not have such a statute.
Some transactions that involve a transfer of funds from States to local governments are shown as direct State expenditures, rather than as intergovernmental payments. These transactions include: (1) amounts paid to local governments under contractual agreements for construction or maintenance work on the State highway system for the State highway agency; and (2) payments on local debt obligations assumed by the State as reimbursement for the cost of local roads added to the State highway systems.
Numerous other State transactions or activities benefiting local governments do not involve a transfer of funds and are not treated as intergovernmental payments. These transactions include:
- (1) advisory, consulting, and supervisory services, engineering assistance, and aid-in-kind (e.g., free provision of road materials or loans of equipment);
- (2) State assumption of the responsibility for construction and maintenance of former county roads or municipal streets;
- (3) direct State payments for materials or to contractors for the State's share of the cost of joint State-local projects on local road systems; and
- (4) direct work by the State on locally controlled roads and streets.
The highway finance activities of local governments are estimated in the LGF table series. Table LGF-21 consolidates and summarizes all highway receipts and disbursements of local governments. Some States use sampling to develop highway finance data for local governments. As mentioned earlier, highway finance data for local governments are collected every other year, and therefore some tables may display data for the previous year.
Most local governments are constrained by their State governments to the taxation of real and personal property as their primary source of revenue. Because there are limits to the amount of revenue that can be derived from property taxation, many States share revenues with local governments.
Recently, as States have increasingly permitted local governments to impose their own highway-revenue fees, more highway-user revenue is being reported from local governments. Local highway-user taxation is usually in the form of local option taxes on motor fuel. With a local option tax, the State allows local governments to decide whether to levy a tax to be added to the State tax rate. Typically the local option tax is then collected and administered along with the State tax. Regional gasoline taxes are considered to be local highway-user taxes unless levied uniformly throughout the State. See the discussion under "Classification of Highway Receipts."
Local government transfers to States
Receipts and disbursements on Federal-aid projects are usually considered transactions of the State. However, local funds may be expended on such projects. When local governments provide the matching share and the State administers the project, the payments to the State are considered to be intergovernmental transfers.
In some States, a portion of the local share of State tax revenues is not paid directly to local governments. The revenues are retained by the State to match Federal funds for locally controlled road and street projects, or to reimburse the State for work performed at the request of the local government. When the State retains such tax revenue, the transactions do not appear as intergovernmental payments in the State or local finance series of tables.
Classification of Highway-User Revenues
Taxes and fees imposed on the owners and operators of motor vehicles for their use of public highways are classified as highway-user taxes and the revenues generated as highway-user revenues. Most highway-user revenues are used for highways, but some are used for mass transit or nonhighway purposes. See Tables HDF, SDF, DF, MF-3, MV-3, and LDF for the disposition of highway-user revenues.
The clearest example of a highway-user tax or fee is a toll. Before either entering or exiting a toll facility, the driver of a motor vehicle must pay a toll for the use of the highway.
Most motor fuel taxes are classified as highway-user taxes. In most States, wholesale distributions initially pay the tax, and the costs are ultimately passed down to motor fuel users.
For motor fuel revenues to qualify as highway-user revenue in FHWA tables, a motor-fuel tax must be levied per unit of volume, e.g., per gallon. It must also apply only to motor fuel opposed to all petroleum products, or all hazardous materials or provide a separate rate for motor fuel.
The motor fuel revenue data reported by the States may include small amounts of revenues generated from the nonhighway use of motor fuel. In many States, nonhighway use is tax exempt or subject to refund. In other States, nonhighway use is taxed, but the revenues might be separately identifiable, and may be dedicated to special accounts for non-highway purposes. For example, tax revenues generated from boating use are sometimes dedicated for improvement of boating facilities. In cases where non-highway use is taxed and the revenues are commingled with receipts from highway use, the revenues from non-highway use will appear in FHWA tables. An example is the gasoline used in lawnmowers, which is not separately identifiable from that used for highways.
Motor-vehicle registration fees, certificate-of-title fees, driver-license fees, and other miscellaneous vehicle fees are all highway-user taxes, since they are imposed on owners and operators as a condition prior to use of a motor vehicle on the highways. Weight-distance taxes, oversize-overweight permits, and trip permits are even more directly related to highway use.
Additional special fees imposed on registrations are counted as highway-user revenue although they may not be viewed as such by some States. These additional fees include surcharges for vehicle emission programs or emergency medical services.
Not all taxes paid by highway users are classified as highway-user taxes. Those taxes and fees that target a broader base than highway users are considered to be part of the general tax structure of the State, and are not considered to be highway-user taxes. Most sales and use taxes, gross receipts taxes, and ad valorem property taxes are not targeted specifically at highway users. They are imposed on all sales transactions, business receipts or property.
For example, special environmental taxes imposed equally on all petroleum products, or all hazardous materials, are not considered to be highway-user taxes. Although highway users indirectly pay some of these taxes, they are not being targeted for their use of highways. These taxes are being imposed on a broader group of users of materials that potentially can cause environmental damage. However, environmental fees that are imposed solely on motor fuel or that provide a separate tax rate for motor fuel are considered to be specifically targeted at highway users and are then classified as highway-user revenue.
State sales taxes imposed on motor vehicle sales are typically not classified as highway-user taxes because they are usually imposed on all sales transactions and are a part of the general tax structure of the State. When motor vehicle sales are charged a separate tax rate from that imposed on general sales transactions, the motor-vehicle sales tax revenue is considered highway user revenue. In this case, the sales tax is specifically directed at highway-users.
Classification of Highway Receipts
Highway receipts shown in the HF, SF, and LGF table series include highway-user revenue and all other receipts that are expended for highway purposes, regardless of source. Highway-user revenues that are used for non-highway purposes are excluded.
Funds attributable to highway users
Many States have legislatively dedicated highway-user revenues to specific purposes. For example, a State might dedicate 70 percent of its motor-fuel tax revenues for highway construction, 10 percent for State highway debt service, and 20 percent for schools. Under these circumstances, the SF table series would reflect the construction and debt service dedications, but would not include the amount dedicated for schools.
When highway-user revenues are dedicated to multipurpose funds and mixed with other revenue, it is impossible to precisely identify how revenues from particular sources are used. In this case, the FHWA would estimate motor-fuel and motor-vehicle revenue proportionally to each type of expenditure made by the multipurpose fund.
Some States allocate highway-user revenue to the State general fund and then appropriate general funds to highway purposes. In the FHWA analyses, the amount flowing into and out of the State general fund is offset, so that the highway-user revenues are treated as if they went for highways directly. Tables DF, MF-3 and MV-3 show the amounts that were offset in this fashion.
Tables MF-106 demonstrates the legislative and administrative provisions for allocating State motor-fuel taxes. Table MV-106 provides similar information for motor-vehicle registration fees, driver-license fees, and motor-carrier taxes. These tables are published in the FHWA publication, Highway Taxes and Fees, How They Are Collected and Distributed.
Other taxes and fees
All taxes that are dedicated for highways, but are not classified as highway-user revenues, are shown as other taxes and fees. The most common of these taxes are general sales and use taxes, gross receipts taxes, ad valorem property taxes, and severance taxes. Only the amounts allocated to highway purposes from other taxes and fees appear in the tables. Specific dedications and appropriations for highway purposes from State taxes and fees, are shown in table S-106 in the FHWA publication, Highway Taxes and Fees, How They Are Collected and Distributed.
Investment income and miscellaneous receipts
By investing surplus or unused highway funds, many highway agencies are able to realize interest income or profit on the purchase and sale of securities. Other miscellaneous income includes: private donations (including cash contributions and transfers of real property); sign fees; insurance recoveries; rentals; fines and penalties; and permit fees.
Funds from a number of sources are deposited into State and local general funds and effectively lose their identities. Except for highway-user revenues, no effort is made to track the ultimate revenue source of general fund appropriations that are used for highways.
Differences exist between States as to the types of revenues used in funding highways. State and local governments do not impose the same taxes and fees. The tax structure and distribution of tax revenues varies from State to State and from local government to local government. These differences are often found in how States choose to finance their highway systems and in how States classify revenues.
For example, some States extend paying for a project into the future through bond financing. Large bond sales can greatly inflate the amount of revenue for highways in the year the bonds were sold, especially when total revenues are compared to prior and subsequent years. Similarly, total disbursements can vary greatly with the expenditure of the bond funds.
States which do not use bond financing pay for projects by either accumulating sufficient funds before beginning the project, or paying for the project from current revenues. Those States tend to have a more consistent level of revenues and disbursements than States which use bond financing.
Another example involves toll financing. Not all States have toll facilities, and the size and financial scope of toll facilities varies significantly. A small toll facility may raise and spend a few thousand dollars a year. Some large toll facilities have cash flows of several hundred million dollars to over a billion dollars a year. Toll facilities can represent a significant portion of a State's highway revenues and expenditures. Toll facilities also represent a significant source of revenues for mass transit and other purposes.
The classification of revenues varies from State to State. FHWA reclassifies some State revenue data to present tables with more uniform definitions. Revenues generated by taxes and fees that are specifically targeted at highway-users are classified as highway-user revenue. See the discussion on "Highway-User Revenue" for details on the FHWA definition. Taxes that are imposed more broadly, such as State sales taxes, are classified as "Other State Taxes," even if the taxes fall on the highway user.
Full data on the collection and disposition of highway-user revenues are included in Highway Statistics. However, revenues from other taxes and fees are shown only to the extent that their proceeds are used for highways. Therefore, it is not appropriate to draw conclusions about the total amounts of taxation in these other areas, since only a portion of the proceeds is accounted for.
Revenues whose origins are unidentified are also typically classified as general funds. For example, when State highway agencies receive payments from other State agencies for expenditure on highways, it may not be possible to determine the original source of revenue of the transferred funds.
DebtObligations for Highways
Income from sale of bonds and notes
Short-term note issues (a maturity of 2 years or less) have been omitted from all revenue and expenditure tables. Although local governments use short-term debt financing frequently, short-term note issues and redemptions are only included in table LGB-2 for the local finance (LGF) table series. Interest payments for short-term debt are included in the highway finance summary tables.
Tables that give details of State obligations (SB table series) and local obligations (table LGB-2) have been included. Separate tables have been provided for State and local toll obligations and for State obligations for local roads and streets.
Some bond issues combine borrowing for more than one purpose. The highway share of combined debt in the tables may be estimated. The SB table series provides details of the highway debt transactions of the States. Debt status for local governments is given in table LGB-2.
Apportionments, Obligations, and Expenditures
Federal Aid to State and Local Governments
The Federal-aid highway program is administered by FHWA as a grant-in-aid program. Funds are apportioned to States in accordance with formulas legislated in Federal legislation. Certain programs administered by the FHWA are funded from Federal general funds. Other Federal agencies may transfer funds to the FHWA to administer for highway improvement projects. Details of the Federal-aid funding process can be found in the FHWA publication, Financing Federal-aid Highways at the URL: https://www.fhwa.dot.gov/policy/olsp/financingfederalaid/
Annual appropriations of Federal-aid funds for the various programs are apportioned among the States using the formulas and factors shown in table FA-4A. For most programs, these funds are matched by State or local governments on an 80 percent Federal share to a 20 percent State share basis. Amounts apportioned to the States for a fiscal year are not to be confused with payments to the States for work completed. Although Federal-aid funds are apportioned by year, a grace period before obligating is permitted to allow the States time for orderly planning, budgeting, and execution of their highway programs.
The TEA-21, and the subsequent SAFETEA-LU, legislation expanded the use of State reported information as factors in the apportionment of Federal-aid funds to the States. Table FA-4E shows selected data used for apportionments to certain Federal-aid highway programs. Table FA-4D shows the factors and the weight of those factors in the apportionments. Interstate Maintenance (IM) Program funds are based one-third on a State's share of certain Interstate travel, and one-third on a State's share of commercial vehicle contributions of the Highway Account of the HTF.
National Highway System (NHS) Program funds are apportioned: 25 percent States' share of principal arterial lane miles, 35 percent States' share of principal arterial travel, 30 percent States' share of highway use of diesel fuel, and 10 percent States' share of per capital lane miles.
Surface Transportation Program (STP) funds are apportioned: 25 percent States' share of Federal-aid Highway System lanes miles, 40 percent State's share of Federal-aid Highway System travel, and 35 percent States' share of contributions to the Highway account of the HTF.
State and local governments also receive funds for their highway activities from programs administered by other Federal agencies. Some Federal funds are distributed through State governments to local governments. Federal agencies' direct work on highways represents only a small portion of Federal assistance to highways. The different Federal assistance programs for highways are summarized in table F-106 in the FHWA publication Highway Taxes and Fees, How They Are Collected and Distributed.
Payments to contractors for work on Federal-aid projects are initially made from State or local funds. The Federal share is reimbursed to the States as work progresses. The final reimbursement payment is made after completion of the project.
While most payments by FHWA are reimbursements to the States, some funds are expended directly by FHWA. Tables FA-3, FA-5, and FA-21 provide information on the expenditure of Federal funds. The FA-21 consolidates and summarizes all highway receipts and disbursements of the Federal Government. The FA-4 and FA-6 series provide information on the apportionment and obligation of Federal funds. Table FA-10 provides information on Federal-aid highway program accomplishments for Federal-aid projects initiated during the data year of this publication.
Obligations of STP funds for projects off the NHS are included in the summary tables STP-1 and STP-1A. These tables are intended to show expected products or accomplishments to be achieved with this category of Federal-aid highway funds.
Classification of Highway Expenditures
Expenditures for highways have been grouped into the following major classes: capital outlay, maintenance, highway and traffic services, administration, highway law enforcement and safety, debt service, and intergovernmental payments.
Capital outlays are those costs associated with highway improvements, including: land acquisition and other right-of-way costs; preliminary and construction engineering; construction and reconstruction; resurfacing, rehabilitation, and restoration costs of roadway and structure; system preservation activities; and installation of traffic service facilities such as guard rails, fencing, signs, and signals.
Maintenance costs are those required to keep highways in usable condition and do not extend the service life of a highway if not extended beyond the original design.
Highway and traffic service costs are those associated with the operation and management of highways. These costs are classified into three types. The first type involves traffic control operations, which includes expenditures for operating traffic control and surveillance systems for monitoring and controlling traffic flow. The second type includes the cost of snow and ice removal. The third type includes miscellaneous costs for highway beautification, litter control, vegetation management, erosion control, and air quality programs.
Administration costs are the general expenses of administering a State or local highway program, including general overhead, engineering, and research costs that are not assignable to specific road projects. They also include expenses associated with highway planning and research, highway litigation, and highway publications.
Highway law enforcement and safety expenditures are: traffic supervision activities of State highway patrols; highway safety programs including driver education and training, motorcycle safety; vehicle inspection programs; and enforcement of vehicle size and weight limitations. General police expenses associated with drug interdiction, criminal investigation, and security activities are excluded from the tables.
Debt service costs are the expenses incurred from borrowing funds for highway, road, and street projects. Debt service includes expenditures incidental to the sale of highway bonds, bond administration expenses, interest, and redemption payments.
Intergovernmental payments are transfers of funds between different levels of government. A description can be found in the preceding discussions on Federal Aid to State and local governments, State aid to local governments, and local government transfers to State.
Information for Users
Because highway finance information is statistical in nature, it does not represent an accounting or audited statement of State and local governments. The published highway finance information presents a general overview of the funding of highway programs, highway-user taxation and the disposition of highway-user revenues.
All reports and information provided to FHWA are examined for completeness, reasonable consistency within present and past data reporting, and with data reporting instructions contained in a Guide To Reporting Highway Statistics. The FHWA analytical process may include reclassification of State data to achieve greater consistency in the presentation of the data.
The reporting of information varies from State to State. How consistent States are in reporting data according to instructions contained in A Guide to Reporting Highway Statistics has an impact on the reliability of comparing the data of different States.
Federal government highway finance data are based on the Federal fiscal year. State government highway finance data may be either fiscal or calendar year at the option of the individual State's highway agency. Local government highway finance information is based on the variety of fiscal and calendar years used by local governments. Therefore, data shown for any particular year actually represent a mix of data for calendar and fiscal years ending during the reporting period. Because of the difficulty States encounter in gathering and developing local government highway finance data, the reporting of local government information lags one year behind State government highway finance information.
The information in Highway Statistics on State government highway finance is based on reports coordinated by State highway agency personnel with contributions from a variety of other State agencies that have highway functions, such as tax and revenue agencies, motor vehicle agencies, public utility commissions, public safety departments, and highway police organizations. The completeness and consistency of State government level data is dependent upon the degree of cooperation among State agencies.
Different agencies have different accounting and information systems, which can lead to timing differences in the recording of revenues and expenditures. Timing differences are most apparent in the transfer of funds among the State agencies responsible for collecting revenues and the State agencies responsible for expending those revenues.
The information in Highway Statistics on local government highway finance is based on reports coordinated through State highway agencies from data provided by local governments. States have the option of providing local highway finance data on either an annual or biennial basis with the FHWA estimating the years not reported by the States.
Some State highway agencies develop their local highway finance reports, in part or whole, from central State sources that routinely collect local finance data through legislated local government reporting requirements. Local highway finance information tends to be more consistent for States which provide data each year and which have legislated local government reporting requirements. The reliability of local highway finance data is highly dependent on the degree of cooperation between State and local governments.
States have the option of using a sampling methodology as an alternative to a complete survey of all local governments. Some States use surveys and sampling to supplement centrally collected data. Sampling programs are developed by the State highway agency to fit FHWA reporting needs, the State's needs, available State resources, and local government structure.
Differences exist among States depending on the governmental level of responsibility for highway functions and the variation in agencies that perform the functions. Some States have jurisdictional authority over almost all highways in the State and perform almost all highway functions. In other States, local governments have jurisdictional authority over a significant portion of the highways. Comparisons are difficult to make among State governments which have vastly different highway responsibilities. Local government data also tend to vary among States depending upon the degree of local government responsibility for highways.
Some States share a significant amount of highway-user revenue with their local governments. Other States assist local governments by transferring other revenue or by performing direct work on local jurisdiction roads. States performing direct work on local roads tend to report higher levels of capital outlay, maintenance and administration for the amount of revenues raised.
State accounting and information systems assign expenditures based on internal State categories and definitions. To develop their expenditure reports to FHWA, States modify their internal data to correspond to FHWA categories and definitions. The reliability of the reconfigured data is dependent on the detail present in existing State records, and the amount of variation between State and FHWA definitions.
One area in which States have difficulty in compiling data is in defining types of capital improvements. Project records in some States do not contain a full breakdown of work types. This forces these States to assign projects to categories based on narrative descriptions of each project. Such narratives are of varying levels of detail and are subject to interpretation. This may cause data classification to be less consistent. States use a variety of definitions for capital outlay and physical maintenance. In some States, work performed by maintenance crews may be classified as physical maintenance, even if the project was extensive enough to meet the FHWA definition of capital outlay.
Another problem area is the assignment of indirect costs. FHWA requests that States assign incidental costs related to specific construction and maintenance projects to those categories. For example, salaries and benefits for engineers and construction workers detailed to a construction project should be assigned as construction expenditures. However, many State accounting systems do not assign costs in this manner. For example, salaries may be assigned to capital outlay while employee benefits may be assigned to general administration.
The treatment of pensions for highway agency employees is a significant source of variation. In some States, the pension system is completely independent and separate from the highway program, and pension payments are not shown as highway expenditures. In other States, highway agencies are required to make pension fund payments as their liabilities are incurred. In this case, pension fund payments are shown as highway expenditure, and should be assigned to capital outlay, maintenance, or administration in the same manner that salaries are assigned. In a few States, the State highway program is charged for current benefits to retired employees. Since it is impossible to tie these benefits to specific construction and maintenance areas, these costs are reported as general administrative costs.
The combined effect of variations in indirect cost allocations and the differences in State highway program structures causes the general administration numbers to vary widely among the States. For these reasons, the administration data are not a suitable measure for comparisons of State administrative efficiency.
Conditions and Safety
The HPMS contains data from two pavement rating systems. One is an objective rating measure, the International Roughness Index (IRI). The other is a subjective rating system based upon the Pavement Serviceability Rating (PSR) or equivalent data adapted from a State's pavement serviceability index, sufficiency ratings, or ratings from a pavement rating table. Both are used as indicators of pavement surface condition. Pavement rating data are not reported for local or rural minor collector functional systems.
Measured pavement roughness
Measured pavement roughness is an objective equipment-based rating reported in the HPMS as IRI in inches per mile (meters per kilometer). These ratings are collected by various mechanical devices, some of which may require calibration through correlation to "known profiles" established via precise measurements. The IRI is a numerical value that is an accumulation of the inches (meters) of vertical movement of a vehicle over a roadway surface, adjusted to reflect a rate per mile (kilometer). Low values indicate a smooth riding quality, while higher values are indicative of a rough road. Because IRI is a more objective, mechanically measured index, IRI should be more consistent between and among States when similar pavement types and surface textures have been measured using similar devices that have been properly calibrated.
Variability in IRI measurements can arise from differences in the equipment used to measure IRI, and differences in the measurement protocols used. In an effort to improve data consistency, FHWA recommends that States follow AASHTO Provisional Standard PP37-99 when reporting IRI data to the HPMS. Additional guidelines intended to improve consistency are included in the HPMS Field Manual; users are encouraged to consult that document. Improvements to measurement equipment and instrument standardization for the most part rely upon Federal and State research activities such as those carried out by AASHTO and the Road Profiler Users Group. While IRI data may be more suitable for comparative purposes than PSR data, the user needs to consider and account for the variability introduced by these and other factors, such as pavement type, when making comparisons. In general, IRI data are reported to the HPMS on an annual basis for the arterial functional systems and all NHS routes. IRI data are used as reported by the States without manipulation or adjustment. Although IRI is a measure of ride quality, the IRI data are also used by FHWA in national level models to predict pavement deterioration, deficiencies, and investment needs.
IRI is a measure of pavement roughness; to have a comprehensive measure of pavement condition; data on other pavement distresses such as rutting, cracking, and faulting are needed. Provisional standards for these measures are being developed by AASHTO, and States will be encouraged to include them in their pavement management systems in the future.
Present serviceability rating
PSR and other subjective measures use a numerical value ranging from zero to five, reflecting poor pavement condition at the lower end of the scale and very good pavement condition at the higher values. These indices provide a judgment of pavement condition based upon an assessment of ride and visual pavement distress by a panel of road users. PSR and PSI were adapted from the American Association of State Highway (Transportation) Officials Road Tests conducted in the late 1950's and early 1960's. Since they are subjective, ride-based rating schemes, and because of the various methodologies used by the States to collect these data, the ratings may not be consistent or comparable among the States.
In general, PSR, or equivalent subjective pavement rating data, are reported to the HPMS on an annual basis where IRI data are not reported. PSR data are input to the HPMS database as reported by the States; sampled PSR data are expanded using the sample expansion factors in HPMS to represent the functional systems for which they are reported. Although PSR is primarily a measure of current ride quality, PSR data are used by FHWA in national level models to predict pavement deterioration, deficiencies, and investment needs where IRI data are not available.
Estimating congestion measures
The FHWA uses a traffic volume-service flow ratio (V/SF) as a measure of congestion in Highway Statistics. The V/SF is a computed numerical value based upon traffic volume information and roadway capacity calculated for each sampled section of roadway. The calculation of the peak capacity is done in general accordance with estimating procedures contained in the latest Highway Capacity Manual (HCM), which was developed by the Transportation Research Board. The user of these data has a responsibility to assure that the application of V/SF from the HPMS is suitable to the purpose for which the congestion analysis is being conducted. Note that the method used to calculate the data shown in Table HM-62 and System Congestion Trends Chart has changed; a weighted average based on length is now used to calculate average daily vehicles per lane.
International and Metric
Conversions to Metric
In this section, FHWA provides some tables in metric format (metric tables contain an "M" at the end of the table name as shown in the Table of Contents). A soft conversion from English to metric has been made using 1 mile = 1.609344 kilometers for the individual values and 1 gallon = 3.785541 liters. Because this is a soft conversion totals may not agree with the equivalent English-based tables. All metric tables are provided in the International Section of Highway Statistics.
While many of the tables produced for Highway Statistics have footnotes provided at the bottom of the table, in several cases, the footnotes are so extensive that they are provided separately. Those extensive footnotes can be found in this section.
This section of Highway Statistics contains a list of acronyms and a glossary of terms commonly used by transportation professionals in their work. This section may be most useful to those who are not already familiar with these terms.