The WMATA Riders Union, an advocacy group for Metro riders, appears to have gone off the rails just like one of the dysfunctional trains its members have so often complained about.

The leadership team at the riders union has dwindled to one. The last time its Twitter feed stirred with information on Metro operations was April Fool’s Day, and its Web site has grown ominously quiet. And no one inside is saying what’s going on with an organization whose Web site claims its membership is now more than 1,700 people.

That’s a dramatic change from six months ago. Back then, the WMATA Riders Union, cresting on a surge of commuter angst and guarded optimism, drew at least 100 people to its inaugural meeting on Oct. 19 at the District’s Martin Luther King Memorial Library. There was talk that night of raising the group’s profile, setting up booths at public events to recruit new members and making regular appearances before the board that governs the Washington Metropolitan Area Transit Agency (WMATA).

In November, Metro general manager Paul J. Wiedefeld paid a visit to the group’s leadership team a day after taking Metro’s top job. He met with the riders union membership in December. The WMATA Riders Union seemed to be answering the need for citizen engagement and advocacy at a time when Metro’s long-running financial and safety issues had made one of the nation’s busiest subways a national laughingstock.

And then — almost nothing.

“My sense is, it’s dead,” Chris Barnes, a founder and former leader of the Riders Union, said this week. “And I’m not happy about it in the least. This is something that, now more than ever, we need.”

Barnes, who serves on Metro’s Riders’ Advisory Council, built a substantial Twitter following of Metro activists that helped lay the foundation for WMATA Riders Union. But Barnes, AKA @FixWMATA, said he’s not sure what’s going on at the group. Barnes — whose defenestration from the group’s leadership team came about last fall because he was seen as too much of a firebrand — has raised questions about the riders union’s direction and finances, especially because he had invested $2,000 in the organization. Last he heard, however, the group didn’t have the money to pay for sign-language interpreters at its inaugural meeting.

Roger Bowles, another early leader of the riders union, said late Wednesday he has no clue what’s going on with the group now. Bowles, a former retail operations manager at Verizon Wireless who was to serve as WMATA Riders Union’s operations consultant, said late Wednesday that he hasn’t talked with its leadership since he left the organization last October. Since then, he has helped form Rail Transit OPS Group, a joint venture that bills itself as offering independent analysis and monitoring of mass transit systems.

The WMATA Riders Union has acknowledged its dormancy in a rueful message posted March 9 on its Web site. But the leadership has revealed little more about the group’s status.

It also issued an advisory on March 9 asking people to apply to join the leadership team. But how that search is going, who’s applied (has anyone applied?) or whether anyone’s even answering the phone or picking up the mail over there — it’s all a mystery. Into the void the Twitterverse has called out now and then seeking answers, only to be met by silence or speculation.

On its Web site, the organization’s leadership team lists one person: Ashley Robbins, who tweets under the handle @CCTgirl. Efforts to reach her by telephone and email this week were not successful.

“Ashley just stopped responding to all communications,” Graham W. Jenkins, who was at one time the WMATA Riders Union’s vice chair and communications director, said Thursday morning. “None of us has any insight as to what’s going on.”

Jenkins said that he left the group in February because Robbins became incommunicado while still  retaining control of the group’s finances and Web site. His email now carries a note saying that his account is inactive and directs further inquiries to Robbins.

“I’m hoping it’s hiatus, just waiting for her to respond to calls and emails,” Jenkins said.

Train operators with garbled speakers have been more communicative about what’s going on than the WMATA Riders Union right now.

And that’s a pity, because Metro needs a riders union — and not just Metro, really, but everyone affected directly and indirectly by its mass transit system. Washington commuters put up with a lot, but they shouldn’t have the added indignity of having to ask the group that’s supposed to ask Metro to get its act together, to get its act together.

 –This posting has been updated to correct the date of the meeting with sign language interpreters.