Capital expenditure: Capital expenditure includes outlays for adding new equipment and structures and for improving or enhancing the capacity and quality of the existing equipment and structures if the improvements last for more than 1 year. Capital expenditure enhances the capacity and efficiency of the transportation system, either by directly expanding the capacity or by improving the efficiency of the system (i.e., reducing travel times, improving access, reducing costs, or reducing adverse safety and environmental effects).

Chained 2005 dollars: Chained 2005 dollars include dollar values of inflation-adjusted government revenues and expenditures are provided using 2005 prices. These estimates are derived by dividing the current dollar values by chain-type price indexes.

Chain-type price index: This index measures movements in prices over time. Chain-type price indexes are compiled by BEA using Fisher’s ideal price index formula. The Fisher ideal price index is a geometric mean of a Laspeyres and a Paasche price index. The change in the index falls between the changes in the Paasche and Laspeyre price indexes. The annual changes in Fisher’s price index are chained (multiplied) together using weights from two adjacent years to form a time series of changes. For example, the 1998–1999 annual percent change in prices uses quantities for 1998 and 1999 as weights, and the 1999–2000 annual percentage changes in prices uses quantities for 1999 and 2000 as weights.

Current dollars: Current dollars is the dollar value of a good or service in terms of prices current at the time the good or service is sold. This contrasts with the value of the good or service measured in constant dollars.

Federal direct expenditure: Federal direct expenditure refers to all outlays of the Federal government, excluding grants.

Federal grants: Federal grants refer to financial assistance awards that provide payments in cash or in kind for a specified purpose. The Federal government is not expected to have substantial involvement with the State or local government or other recipient while the intended activity is being performed. The term ―grants-in-aid‖ is commonly restricted to grants to State and local governments.

General fund: A general fund consists of accounts for receipts not earmarked by law for a specific purpose, such as income taxes and many excise taxes, the proceeds of general borrowing, and the expenditure of these moneys.

Intragovernmental fund: An intragovernmental fund includes revolving funds that conduct business-type operations primarily within and between Federal government agencies. The collections and the outlays of revolving funds are recorded in the same budget account.

Offsetting collections: Offsetting collections are collections from the public that result from business-type or market-oriented activities and collections from other government accounts (i.e., intragovernmental transactions). These collections are deducted from gross disbursements in calculating outlays rather than counted in governmental receipt totals. Some offsetting collections are credited directly to expenditure accounts, while others (i.e., offsetting receipts) are credited to receipt accounts.

Operation and maintenance expenditure: An operation and maintenance expenditure consists of recurrent payments to cover the cost of administration, operation, and normal maintenance and repair of the transportation infrastructure and facilities. Such outlays are crucial to maintain the nation’s transportation infrastructure and provide a safe and efficient transportation system.

Own-source revenue: Own-source revenue consists of  government receipts from transportation-related taxes and charges earmarked to fund transportation programs. There are two criteria that distinguish own-source from other types of transportation revenue: the revenue is generated from transportation sources, and it is used for financing transportation programs.

Revenue directed to other uses: Revenue directed to other uses consists of government receipts from transportation-related taxes and charges, which are not used for transportation purposes. Such revenue is raised from transportation sources and is used to finance activities other than transportation.

Supporting revenue: Supporting revenue consists of receipts that are generated from non- transportation sources but are designated to fund transportation programs. There are two criteria that distinguish supporting revenue from others: it is not generated from transportation sources, which implies that the receipts are raised through charges or taxes levied on industries or activities other than transportation, and it is designated to fund transportation programs.

Trust fund: A trust fund is an account established by law to hold receipts (such as specific taxes or revenues) collected by the Federal government and earmarked for financing special purposes and programs. To assure the financial soundness of a trust fund, it must be tracked separately to determine that outlays/expenditures do not exceed available revenue.

User charge or fee: A user charge or fee is an assessment on users for goods and services provided by the Federal, State, or local government. User charges, either directly or indirectly, are collected on a periodic or occasional basis in the form of license fees and excises. A user charge is paid at the time infrastructure services are consumed, as with the payment of fuel taxes or tolls. In the narrow budgetary sense, a toll for the use of highway is considered a user fee since it is related to the specific use of a particular section of highway. Highway excise taxes on gasoline are considered a form of user charge in the economic sense; however, since the tax must be paid regardless of how the gasoline is used and because it is not directly linked to the provision of the specific service, it is considered a tax and recorded as a governmental receipt in the Federal budget.