Both parties -- the T and the disabled riders who sued the agency -- agreed to appoint Patrick King, a state judge and federal mediator with the First Circuit Court of Appeals, as an independent monitor.

By December, the MBTA is expected to meet the terms it agreed to 19 years ago. At that point, the settlement will end, Judge King will retire, and a group of disabled riders will take on his role.

Joanne Daniels-Finegold, 72, the lead plaintiff of the class action lawsuit that resulted in the 2006 settlement, said she was cautiously optimistic about the change.

"There's been too much work on the part of all of us plaintiffs for it all to go to waste," said Daniels-Finegold, who uses a wheelchair and is on the executive board of the citizen group that will take over monitoring the T.

At the turn of the 21st century, she estimates that just six Green Line stations had bridge plates available for people to wheel themselves over wide platform gaps. Bus drivers also regularly refused to stop and put down the lift for passengers with disabilities to board, she said. The settlement, which, among other improvements, pushed for sensitivity training for bus drivers, vastly improved matters for disabled riders.

As the 2006 settlement winds down, the surviving plaintiffs expressed mixed feelings. Without an independent monitor with legal authority, they worry that it might be harder for riders with disabilities to be taken seriously by T officials. On the other hand, the transit agency now has a dedicated department to monitor system-wide accessibility.

Taramattie Doucette, an attorney at Greater Boston Legal Services who was lead counsel on the lawsuit that led to the settlement, said that King acted as an important advocate to enforce the terms of the settlement.

For example, when King was first appointed in 2007, he would deploy pairs of "secret shoppers," typically one person with a disability and one without, to ride the system together and take notes on everything from the quality of stop announcements to how the bus driver treated them to track progress.

Despite King's impending retirement, Doucette said, the upcoming change is exciting and innovative.

"Power rests with the people, this is how it should be," Doucette said. "The community can lead and can get things done."

King, the independent monitor who's retiring, agreed that it was time to move on.

"Over time, my role has really diminished because there are so few problems that I need to address," King said, "I think there'll be a smooth transition."

King's oversight role will be taken on by a citizen group called the Riders' Transportation Access Group. Katarina "Kat" Torres Radisic, who works for the Boston Center for Independent Living, an organization that was one of the 12 plaintiffs in the original case, helps to organize the new group's meetings and recruit new members.

"I think some of us fear that when this legal component goes away, the MBTA might start to slip on the commitments that it's made," Radisic said. "There's always the possibility that we sue again."

For its part, the T is training transit police officers with a focus on accessibility, the agency's general manager Phil Eng said during a presentation at a meeting in June.

Myrnairis "Mic" Cepeda, one of the plaintiffs in the original lawsuit, is skeptical about a group of citizens taking over. Cepeda got involved in the lawsuit because she suffered several injuries in the 1990s and early 2000s when bus drivers would close doors when she was still disembarking.

She has spinal stenosis, severe arthritis, and muscle degeneration which makes it hard for her to walk. Cepeda said newer members of the Access Group don't recognize all the work the plaintiffs did over the past 20 years.

"I've been to two RTAG [Riders' Transportation Access Group] meetings and I've never returned," Cepeda said. "They need to know what the history is. If you don't know the history, you're bound to repeat it."

Andy Forman, 61, a plaintiff in the original case, sympathizes with Cepeda, but is keeping an open mind about the transition from judicial oversight.

"I want to make sure that we still have the opportunity to go back to court to sue them if we have to," said Forman, who is legally blind and works at the Boston Center for Independent Living. One of Forman's passions is improving stop announcements.

"If I'm riding the train with you ... I should concentrate on the conversation as opposed to having to memorize and count stops," Forman said.

Forman added that he feels heartened that many staff members in the transit agency's system-wide accessibility department have disabilities, such as the assistant general manager, Laura Brelsford.

"We have a seat at the table," Forman said of Brelsford. "We'll just have to hold her accountable."

Tom Gilbert, another plaintiff in the original case and is visually impaired, feels positive about the transition to citizen oversight because of Eng's focus on improving accessibility.

But Gilbert, who lives in Somerville, also thinks there needs to be greater cooperation between the T and municipalities. That coordination is one of the final terms of the settlement that the transit agency is working to comply with before December.

Getting off the 88 bus at the Clarendon Hill affordable housing apartments stop, Gilbert often hits his cane against uneven potholes. He just wants somebody, anybody, to fix the problem.

"These issues get thrown around like a political football between the city of Somerville, the MBTA, and MassDOT for years," Gilbert said.

Forman said he's staying in the fight though after the judge retires.