MARTA has spent more than half the proceeds from an Atlanta sales tax on enhanced bus service and other operations — a move critics fear will hinder the agency’s plans for new transit lines.

Atlanta voters approved the half-penny sales tax for transit expansion in 2016, and MARTA later approved a $2.7 billion expansion plan that included 29 miles of light rail, 13 miles of bus rapid transit and other improvements.

The plan also included $238 million for new bus routes and enhancements to existing routes — or about 9% of the expected proceeds over the 40-year life of the tax. But MARTA has spent $181.2 million of the $371 million collected so far on enhanced bus and paratransit service and related capital costs, according to a recent report to the Atlanta City Council. It’s spent an additional $15.3 million to operate and maintain the Atlanta streetcar.

MARTA has spent just $36.5 million of the sales tax proceeds on capital expansion, though it has set aside $133.7 million for that and the streetcar, according to the report.

Matthew Rao, an advocate for transit on the Atlanta Beltline, said spending so much on bus operations undermines the will of voters who believed they were supporting new transit lines.

“MARTA has misspent money on operations that was intended to fund capital projects,” Rao said.

MARTA officials say their expansion plans are still moving forward. But they say rising construction costs — not the bus spending — may force the agency to revisit those plans.

“When project costs go higher than anticipated, difficult decisions will need to be made,” Assistant General Manager Carrie Rocha said. “Those may include scaling back on a project or deferring a project to later than anticipated.”

Those comments are the latest signal that MARTA may be backing away from some of the construction plans it announced after voters approved the transit sales tax.

The agency has several new Atlanta transit lines in various stages of planning, including the Summerhill bus rapid transit line and a streetcar extension to Ponce City Market. It’s also renovating rail stations and making other capital investments.

But MARTA appears to be backing away from the light-rail lines it announced in 2018. In February it said it will pursue cheaper bus rapid transit instead of rail on Campbellton Road. In April it said it may pursue bus rapid transit on the Clifton Corridor. And MARTA’s capital programs chief recently said light rail on the Atlanta Beltline may be too expensive to compete for federal funding.

News of the bus spending only increases Rao’s suspicion that MARTA never intended to build light rail on the Beltline.

“This makes everything so much worse that we thought,” he said. “We have to recoup that money.”

Enhanced bus service was always part of MARTA’s Atlanta expansion plan, but it’s clear the portion of the sales tax devoted to it has grown from initial plans. What isn’t clear is when MARTA made the decision to dedicate half of the sales tax proceeds to enhanced bus operations.

Rocha said she was not sure when the decision was made. But she said it was made with input from city officials and the public. She said plans for additional routes and more frequent service on existing routes came from an analysis of bus service that MARTA finished in 2016.

“A lot of these enhancements were things the city wanted to see move forward as part of that operational analysis,” Rocha said.

The streetcar’s operating costs were added to the sales tax budget when MARTA took over the rail line from Atlanta in 2018.

City Councilman Amir Farokhi, who chairs the council’s transportation committee, said he knew enhanced bus service was part of MARTA’s Atlanta expansion plans. But so were numerous construction projects, he said.

“We haven’t seen any shovels in the ground over the last six years,” Farokhi said. “And, so, I think it’s appropriate for the council and for residents to be asking hard questions as to how these tax dollars are being spent.”

City Council President Doug Shipman echoed those comments. He said he wants to make sure MARTA takes advantage of the transit funding included in the bipartisan infrastructure law Congress passed last fall.

“How did we get to where we are?” Shipman said. “It feels like we should have been further along.”