National Capital Transportation Amendments

National Capital Transportation Amendments - Amends the National Capital Transportation Act of 1969 to authorize the Secretary of Transportation to make contributions to the Washington Metropolitan Area Transit Authority, in addition to those already authorized by such Act, for the purpose of financing in part the construction costs of the Adopted Regional System (Metrorail). Requires a matching contribution by the local participating governments in a total amount that is not less than 25 percent of such additional Federal contributions. Authorizes the appropriation, for such purposes, of an amount not to exceed $1,700,000,000 for fiscal years beginning on or after October 1, 1980.

Directs the Transit Authority to establish a sinking fund for the accumulation of assets for payment of principal on bonds and other obligations issued by the Authority. Authorizes the Secretary to make contributions to such fund beginning October 1, 1997, and requires a matching contribution by the local participating governments in a total amount not less than 25 percent of such Federal contribution.

Permits the Transit Authority to use income from the investment of moneys in such sinking fund to pay interest costs incurred on obligations it has issued since July 13, 1972, but only after the Secretary has made interest payments in accordance with existing provisions of such Act. Permits the Secretary to contribute to the Transit Authority amounts sufficient to pay 80 percent of the remainder of such interest costs, after the Secretary has made the direct payments provided for by such Act.

Authorizes the Secretary to make an annual contribution to the Transit Authority (without requiring matching contributions by the local participating governments) in order to finance in part the operating and maintenance costs of the Authority's rapid rail transit system. Authorizes appropriations for this purpose for each of fiscal years 1980 through 1987.