Metro General Manager Paul J. Wiedefeld. (Cliff Owen/AP)

Federal concerns about worker safety lapses combined with growing union tensions and an early morning Red Line meltdown culminated in one of the most contentious board meetings of Metro General Manager Paul J. Wiedefeld’s tenure Thursday.

As board members scrutinized Wiedefeld’s progress on safety, scores of union workers stormed out of the agency’s headquarters chanting “Who moves this city? We move this city!” in the latest example of rising tensions between the two sides during contentious labor negotiations.

Wiedefeld spent much of the meeting on the defensive — at one point forced to reaffirm his faith in top Metro leadership after a board member questioned whether any progress was being made, or the beleaguered agency was simply slipping back into old habits.

The protest — the second in a row at a board meeting — underscored the potential for labor unrest at a time when Wiedefeld is seeking major concessions from the union. He also is engaged in discussions with elected officials and business groups who are pushing Metro to cut labor costs in exchange for more money for operations and capital projects.

“Any time you’re in contract negotiations, it can be tough,” Wiedefeld said after the demonstration. “Unfortunately, I think we’ve had some issues here that I’m raising that I feel need to be addressed. It plays out the way it plays out. I intend to be very civil in our reaction, and professional in anything we do.”

Speaking to reporters outside Metro headquarters shortly after the chanting exodus, Amalgamated Transit Union Local 689 President Jackie Jeter said Metro management is seeking concessions that would reduce workers’ total wage and benefits package by $100 million.

“They want to change everything: wages, pensions, health care, vacation,” Jeter said.

She said management is not offering any wage increases in the next contract, while the union is seeking annual 2 percent increases for the life of the contract. The last contract was four years; the length of the contract under negotiation has not been determined.

Jeter accused Wiedefeld of publicly saying that only future hires would receive less-generous pension benefits, while at the same time negotiating to reduce the value of pensions for current employees, as well.

Wiedefeld declined to discuss contract negotiations.

“We have a confidentiality agreement,” Wiedefeld said. “We signed onto it, and I’m going to hold onto it.”

Jeter said she was breaking the agreement because in her view, Wiedefeld had done so when he outlined his long-term financial plan for Metro last week, which includes several concessions he is seeking from the unions.

The union protest was part of what had been a bad morning for Wiedefeld. A chaotic commute drew national attention to the transit system after stray electrical current caused smoke to pour into a Red Line tunnel in one of the system’s busiest corridors. Wiedefeld said the meltdown underscored the need for the preventive maintenance program he plans to institute beginning July 1.

“We have to work through decades of not maintaining things, things aging out, and we have to replace them,” he said. “That is not going to be solved overnight.”

Then the board hammered Wiedefeld and his safety chief with questions about a Federal Transit Administration letter that cited the agency for ongoing deficiencies in safety protocol for track workers, which have placed them in harm’s way four times recently, the federal oversight body said.

FTA wrote to Metro this week ordering the agency to submit plans to address six deficiencies related to roadway worker protection within five business days or risk losing up to 25 percent of formula-based grant funds until the issues are addressed. The agency stands to lose millions in federal funding.

Metro said it will submit the plans by Monday

Among those plans, it said, is a multitiered safety system, including a track worker waving a large orange flag to mark a work zone, and a blinking light as an additional precaution. Meanwhile, train operators will hear a “script” with specific information about the work zone and protective measures in place. Metro said it will inform workers of the changes at a safety stand-down in May.

Still, board members said the letter — raising renewed concerns over the agency’s troubled Rail Operations Control Center — highlights an information disconnect between the transit agency and its governing board.

“What I’m reading between the lines is we’re not getting an accurate portrayal of what’s going on,” said board member Leif A. Dormsjo, pressing Wiedefeld on ongoing issues in the ROCC. “We’re kind of slipping back into old WMATA, where management kind of glosses over problems and doesn’t provide us a clear understanding of what’s going on.

“We’ve been through other safety directors and we may have to go through more,” said Dormsjo, who is director of the District Department of Transportation.

The ROCC, which acts like air traffic control for the rail system, was cited by the National Transportation Safety Board in its investigation of the January 2015 L’Enfant Plaza smoke incident.

“I would disagree — I think we are not glossing over anything,” Wiedefeld said. “We’ve worked through this, we are working through this and we continue to do it. There’s other issues that we need in terms of resources.”

“I know there’s been a tremendous change in the approach,” Wiedefeld added later.

In one incident noted in the FTA letter, a train nearly struck two federal inspectors and a Metro track worker near Reagan National Airport station in October, after a train zipped around a blind corner faster than the 10 mph speed limit, forcing the three to jump out of the way.

“I was surprised by the letter, because I thought relationships and work relationships were proceeding well,” said board member Carol Carmody. “FTA said they are — they were satisfied with the relationship here. They thought WMATA was working very hard. Their concern was there have been some incidents with roadway safety and they felt that as a regulator they needed to get out there with the letter, with recommendations and some actions required.”

Board member Michael Goldman pressed Wiedefeld and Chief Safety Officer Patrick Lavin on why Metro had continued trouble hiring and maintaining qualified rail traffic controllers. Lavin and Wiedefeld said the process requires time and rigorous training, with Lavin adding that it took eight months to ready a rail controller for the job, and that failure and attrition rates also interfered with the process.

“Through the years, I’ve heard that,” Goldman said. “Every CEO, every chief safety officer has told this board that . . . new controllers would be hired and the problem resolved soon. There seems to be something much more going on if we really can’t staff up the number of rail operations control center controllers after two-and-a-half, three years.”

Later at the full board meeting, dozens of union members, wearing black T-shirts with “Fix It Fund It” and “Bargain in Good Faith” packed the hearing room and then erupted in chants.

The woman who led the cries, union organizer Jampsea Campbell, accused Wiedefeld of divisive tactics intended to break up the union.

Wiedefeld, peering over his shoulder at the demonstration, folded his hands in his lap before turning back to the board.