MARTA will get a chance to repair its system using more than a half-million dollar federal grant initially slated for Clayton County public transportation improvements. The Clayton County Board of Commissioners gave the Metro Atlanta Rapid Transit Authority the green light to use $574,163 to make improvements to its transit system elsewhere in the region. The money is from a 2009 Federal Transit Authority grant MARTA got on behalf of Clayton County. The money must be spent before the grant expires Sept. 30. MARTA primarily runs in Fulton and DeKalb counties although it stops at Hartsfield-Jackson International Airport, which is in Clayton.