TAMPA What are the best endpoints for the first leg of Hillsborough County's light rail line? That's the question facing officials at Hillsborough Area Regional Transit. Possible answers now include Tampa International Airport and Interstate 75, or Cross Creek Boulevard in the county's northern reaches. Members of the HART board's finance committee were briefed on those options Monday. Original plans called for studying a segment that would go from downtown to near the University of South Florida. A section running from downtown to Spruce Street in the West Shore area was added to the study later. That prompted discussions of adding the airport, which is less than a mile away from the Spruce Street stop. HART staffers also are collecting ridership data on the northern stretch, which could attract passengers traveling to and from the area's hospitals, the University of South Florida, Busch Gardens and other attractions. HART board member Steven Polzin expressed concern about the project's growing size. 'I'm nervous that we keep wanting to make the scope bigger and bigger and bigger,' he said. 'Ultimately we need to define a first project. And we keep kind of expanding.' Mary Shavalier, HART's chief of planning and program development, said the added lengths won't stall progress on the project and could help win federal money, which she called a 'numbers game.' 'Ridership vs. cost is critical,' she said. Connecting the Spruce Street rail stop to the airport would cost $78 million for a street-level line and $125 million for an elevated line, according to a 2007 study completed by TIA. 'We know we would get good ridership from an extension there,' Shavalier said after the meeting. Next month, the entire HART board will consider adding the TIA stop to its route analysis. The results of that study should be done by August, and public hearings will be scheduled for September. HART will submit the final proposal and request for funding to the Federal Transit Administration in November. Janet Zink can be reached at jzinksptimes.com or (813) 226-3401. 