A bill to amend the Urban Mass Transportation Act of 1964 to authorize certain grants to assure adequate commuter service in urban areas.

Increases to 90 percent the Federal share of funds to assist States and local public agencies in financing the acquisition, construction, and improvement of facilities and equipment for use in mass transportation service in urban areas.

Authorizes the Secretary of Transportation to make grants or loans to any State or local public body to enable it to assist any mass transportation system which maintains mass transportation service in an urban area to pay operating expenses incurred as a result of providing such service. Specifies conditions for such grants or loans.

Provides that, in order to finance such grants and loans, the Secretary is authorized to incur obligations on behalf of the United States in the form of grant agreements or otherwise in amounts aggregating not to exceed $800,000,000. Increases to $6,l00,000,000 the authorization for obligations to finance other specified mass transportation programs. (Amends 49 U.S.C. 1602, 1603)