Gwinnett leaders are expected to vote next week on the formal adoption of the county's new transit development plan — a plan that, among other things, suggests extending MARTA or MARTA-like heavy rail as far into the county as the Gwinnett Place area.

If the plan is adopted, it would serve to start the clock on the county commission's decision about whether or not to hold a referendum on transit expansion this fall. Commission Chairman Charlotte Nash has said that decision would likely need to be made by August in order to get a question on November's ballots.

Original drafts of Gwinnett's transit development plan, which is not binding but would serve as the guide for any kind of future expansion, included a recommendation for a roughly 4.5-mile heavy rail extension from the existing Doraville MARTA station into Gwinnett and the area near I-85 and Jimmy Carter Boulevard.

The final version suggested extending nearly seven more miles of heavy rail from the potential transit hub near Jimmy Carter all the way up to the Gwinnett Place Mall area, where the county has already acquired land to expand its existing transit station. But while every other potential project in the plan — which also includes several "bus rapid transit" lines and greatly expanded local bus service — has potential revenue streams identified, the longer rail line does not.

The roughly $5.4 billion in projects included in the “original” plan is based on estimates of funding from state and federal sources, and on the county’s residents approval of a new 30-year sales tax made possible by legislation passed earlier this year.

The adoption of the transit plan is included on the agenda for the Board of Commissioners’ Tuesday meetings.

County leaders said it will all probably come down to money.