MARTA chief executive Beverly Scott warned state lawmakers Monday that even if next year's transportation referendum passes, the metro area's largest transit system will still face $2.3 billion in unfunded maintenance needs over the next decade.

"We do not have an answer of how it's going to be funded," Scott said, adding that if the regional transportation plan is rejected, the agency's maintenance costs would spike to $2.9 billion, as the proposed plan includes $600 million specifically for taking care of an aging MARTA system.

But Scott and lawmakers were hopeful other changes can be made to boost MARTA's ability to spend money. Rep. Mike Jacobs, R-Atlanta, the chairman of the MARTOC Committee, said consensus is building among lawmakers in favor of a major change in MARTA funding.

State law says only 50 percent of the money raised by the 1-cent MARTA sales tax paid in Atlanta and Fulton and DeKalb counties can be used for MARTA operations and the remaining 50 percent must go to capital expenses. MARTA supporters have long said that law limits the system's flexibility to spend its money where needed. The 2010 bill that created next year's transportation referendums also suspended the mandatory 50-50 split for three years.

Sen. Fran Millar, R-Dunwoody, suggested to Scott that ending the 50-50 split "is going to help you a lot."

Scott agreed, but noted that next year's referendum would create several additional rail lines in metro Atlanta, all of which would at some point tie into existing MARTA infrastructure, according to a draft project list that must be finalized by Oct. 15. While it's not yet clear whether MARTA or another agency would operate those new lines -- one of which would reach Emory University and another the Cumberland area of Cobb County -- Scott said "every single one of the expansion projects on the list will connect to MARTA."

"We're going to now add, and MARTA doesn't have to operate it, but it's all connecting to that core system and that's going to put additional loads on the system," Scott said.

Voters will decide next year whether to raise their sales tax by a penny for 10 years to fund a $6 billion wish list of transportation projects. A poll conducted this month for The Atlanta Journal-Constitution and Channel 2 Action News found that a scant majority of Metro Atlanta voters support the referendum, but many doubts remain.

Johns Creek Mayor Mike Bodker told the committee his city is "not a transit community" although it would like to be. Its only source of transit today are a few bus routes that are in danger of being lost due to cuts at the Georgia Regional Transportation Agency. And with little transit expected to reach Johns Creek in the proposed referendum project list, his constituents feel as if "our return on investment has not been very good."

Johns Creek residents currently pay the MARTA sales tax but have little opportunity to use it, he said.

At the opposite end of the county, Ralph Moore, mayor of the south Fulton town of Union City, said there are but two bus lines that reach his community. But Moore said expansion of the system should boost Union City's access.

MARTA, he said, "could not sustain expansion of its footprint without expansion of its governance."

The MARTOC committee has held hearings over the past several months as it prepares to consider changes to laws governing MARTA. Jacobs said his goal is to have a bill ready for the 2012 legislative session that begins in January.

And while he and others said they are optimistic changes can be made to the 50-50 funding split, the only way that happens is if a different kind of "fiscal restraint" is put in its place.

After the meeting, Jacobs said that could include requirements that MARTA's reserve fund be maintained at certain levels or even through a cap on administrative hiring and salaries.