Public Transit Improvement Act of 1984

Public Transit Improvement Act of 1984 - Amends the Urban Mass Transportation Act of 1964 to extend from FY 1984 to 1986 the provisions which allow recipients to transfer portions of capital assistance in exchange for operating assistance. Repeals provisions requiring certification of such transfer. Authorizes the Secretary of Transportation to use discretionary funds resulting from such transfer for the replacement, rehabilitation, and purchase of buses and related equipment and the construction of bus-related facilities. Provides that recipients which transfer funds are not eligible for discretionary grants except for emergency purposes.

Increases authorized appropriations for FY 1985 and 1986 for the Mass Transit Account of the Highway Trust Fund and authorizes appropriations for FY 1987.

Authorizes the Secretary to obligate funds for multi-year financing in advance of construction projects.

Authorizes the Secretary to make emergency capital grants to States and local public bodies for the repair or replacement of public transportation equipment and facilities which have been damaged and seriously disrupted as a result of a natural disaster or catastrophic occurrence.

Revises the definition of "associated capital maintenance items" (for which block grants are authorized) by lowering their threshold costs from one percent to one-half of one percent. Authorizes the use of such grants to finance the leasing of facilities and equipment for use in mass transportation service.

Makes funds available from the Mass Transit Account of the Highway Trust Fund for FY 1984 through 1987 for transit crime prevention and security. Authorizes the Secretary to make grants to public mass transit systems for such purpose. Requires recipients of such grants to report to the Secretary, not less than annually with respect to the amount of crime on such systems.

Permits the use of operating assistance funds under the urban mass transit grant program for bus and bus-related facilities if there are no commuter rail or fixed guideway systems in operation in the fiscal year of apportionment.