You could have loaded the optimism onto your Breeze Card when elected officials and transportation advocates spoke at a recent gathering about Clayton County’s upcoming MARTA referendum.

Four panelists — including Clayton County Chairman Jeffrey Turner and MARTA board Chairman Robbie Ashe — agreed that Clayton voters will approve a one-cent sales tax increase on Nov. 4 to join the mass-transit system, thus marking the first expansion of MARTA outside Fulton and DeKalb counties in 40 years.

With that approval will come opportunity.

If voters say “yes” in convincing fashion – and both Turner and Ashe predicted voter assent will top 70 percent — Georgia’s rail future will be brighter than ever, not only in Clayton, but eventually down to Macon, and perhaps elsewhere in metro Atlanta — maybe even under the Gold Dome during the next legislative session.

“It’s crucial for regional transit that it pass, and pass in a strong fashion,” Ashe said.

Other jurisdictions in metro Atlanta are closely watching the vote, he said. An indisputable “yes” vote could get them to think about joining the transit agency.

A resounding victory for MARTA may also turn state legislators’ heads.

“Everybody knows there will be a Plan B discussed in the 2015 General Assembly,” Ashe said, referring to an alternative to the failed 2012 T-SPLOST referendum that was crushed in metro Atlanta. “If we can pass a MARTA referendum with a strong majority, then those folks will be more inclined to give transit generally, and MARTA specifically, a full seat at that table. That’s one of the other reasons why this matters so much.”

Clearly, there’s a lot riding on the vote. But MARTA advocates have reason to be feeling good. The grassroots effort in Clayton is strong. County commission meetings this summer, during which the particulars of the ballot were debated, were packed with pro-transit residents. And a non-binding referendum on MARTA in Clayton a few years back showed strong support.

But even with a victory on election day, there’s a long way to go. The 800-pound gorilla in the room is Norfolk Southern, the railroad company that owns the tracks and right of way MARTA wants to use. Norfolk Southern would have to agree to work with MARTA for commuter rail to be the “high-capacity option” that connects Clayton to Fulton and beyond.

If that doesn’t happen, MARTA will resort to its backup plan, Bus Rapid Transit, something county chairman Turner says his constituents would like to avoid. “The citizens of Clayton County expect commuter rail,” he said. (Bus routes will serve residents within the county under either scenario.)

For his part, Ashe believes negotiations with Norfolk Southern will work out. He explained his confidence regarding the railroad in business terms.

“We’re talking about making a couple hundred-million-dollar investment in their property,” he said. “We want to work out a relationship with them where we can use their right of way, either use their tracks or build a parallel set of tracks in their right of way next to it. We think the right of way is wide enough in most instances to be able to do that. We’d need to do some infrastructure upgrades to some of the bridges and things like that.”

Federal money is in play for commuter rail, too. The long-dormant $45 million in federal funds previously earmarked for commuter rail from Atlanta to Macon remains available. The Clayton sales tax increase would be the local revenue match that unlocks the money from Washington.

“We have the opportunity to do the first real commuter rail in Georgia,” Ashe said. “(The existing line) picks up the big population centers in Clayton County, aside from the airport, but it connects directly to the East Point (MARTA) station. … We think we can have real commuter rail running five to seven years from now. That’s all contingent with us working out a deal with Norfolk Southern. That is not a foregone conclusion, but I’m cautiously optimistic.”

If commuter rail works in Clayton, advocates believe it could change the way mass transit is viewed in metro Atlanta and beyond. Others want to see how the Clayton vote shakes out.

With a big majority, MARTA could suddenly look appealing to other suburban counties choking on congestion – Gwinnett County, for example.

“I just look at the demographics in Gwinnett, and I look at the need in Gwinnett,” Ashe said. “This passenger rail conversation is a parallel that works really nicely between Clayton and Gwinnett. … given the amount of rail line running through Gwinnett County already.”

For the record, Gwinnett Chairwoman Charlotte Nash, in an e-mail Monday, said there are no plans to hold a MARTA referendum in Gwinnett.

Still, with MARTA service improving in general, expansion likely in Clayton and ongoing studies to expand north in Fulton, it will be interesting to see if the General Assembly throws any significant support to MARTA — or transit in general — in 2015.

Robbie Ashe is chairman of the MARTA Board of Directors.