The Federal Transit Administration bestowed Tuesday a $28.8 federal grant to pay for the expansion of the South Florida rail corridor. The federal investment will help fund the final phase of the South Florida Regional Transportation Authority's Double Track Corridor Improvement program, which is building a second set of rail tracks, expanding light rail stations and building new bridges and five replacement bridges, and modernizing grade crossing and signal systems. Reconstruction on the rail corridor, expected to triple ridership to almost 28,000 commuters per day by 2015, is slated to be complete by mid-2005.