An act to amend the National Capital Transportation Act of 1969 to authorize additional Federal contributions for the cost of construction of the rapid transit system of the National Capital Region, to provide an orderly method for the retirement of bonds issued by the Washington Metropolitan Area Transit Authority, and for other purposes.

(Measure passed Senate, amended, roll call #504 (66-23))

National Capital Transportation Amendments of 1979 - Amends the National Capital Transportation Act of 1979 to authorize the Secretary of Transportation to make grants to the Transit Authority to partially finance the cost of construction of the Adopted Regional System.

Stipulates that such grants: (1) be made for work subject to the provisions of the Compact and included in the Adopted Regional System; (2) be matched by the local participating governments in a total amount that is not less than 25 percent of the aggregate amount of Federal grants for each fiscal year; and (3) be subject to such terms and conditions as the Secretary deems appropriate for constructing such System in a cost-effective manner.

Authorizes appropriations up to $1,700,000,000 for such grants. Stipulates that no appropriation be enacted for any fiscal year prior to 1982.

Directs the Transit Authority to establish a sinking fund for the payment of principal on bonds issued by the Transit Authority and guaranteed by the Secretary. Authorizes the Secretary to make contributions of two-thirds of the principal and interest paid or to be paid after June 30, 1979, on such bonds with one-third matching contribution from local participating governments.

Permits the Secretary of Transportation, at the request of the Transit Authority, to make accelerated interest payments with respect to payments due prior to July 3, 1983, up to an additional 18 1/3 percent.

Prohibits the Secretary from making any grant for the cost of construction of the Adopted Regional System unless local participating governments have demonstrated that they have a stable and reliable source of revenue sufficient to meet both: (1) their payments to the Transit Authority for the payment of principal and interest on bonds; and (2) their share of the operating and maintenance costs of the Adopted Regional System.

Directs the Transit Authority, in consultation with each local participating government, to submit a program to the Secretary of Transportation showing that such governments have such revenues.