Under the FAST Act, Congress appropriates funds for transit capital investment under Section 5337 and Section 5339. Section 5337, SGR Program, provides financial assistance to public transit agencies that operate rail fixed-guideway and high-intensity motorbus systems for the maintenance, replacement, and rehabilitation of capital assets, along with the development and implementation of transit asset management plans. These funds reflect a commitment to ensuring that public transit operates safely, efficiently, reliably, and sustainably so that communities can offer balanced transportation choices that help to improve mobility, reduce congestion, and encourage economic development. Section 5339, Bus and Bus Facilities (BBF) Program, provides funding to replace, rehabilitate, and purchase buses and related equipment and to construct bus-related facilities including technological changes or innovations to modify low or no emission vehicles or facilities. Funding is provided through formula allocations and competitive grants. A sub-program provides competitive grants for BBF Projects that support low and zero-emission vehicles. Apportionment levels are somewhat stable but not entirely predictable as they are dependent on the activity of local transit operators relative to the activity of other eligible transit operators.