With a board member frustrated about the lack of significant progress examining the potential for overnight bus service from 1 a.m. to 5 a.m. in Metro Boston, MBTA leadership suggested a possible collaboration with City Hall on the proposal.

"Until we have a schedule and routes and stops, we can't understand what we think the ridership and the cost would be," Transportation Secretary Stephanie Pollack told reporters Monday after a meeting of the T's Fiscal and Management Control Board.

Pollack, who suggested a working group with Boston, said there is always an extensive process before moving bus routes and some communities might object to adding buses that would run well after midnight.

The board in early May first tasked the T administration with investigating the idea for night-long bus service centered in Boston's Copley Square, which was proposed by transit advocates.

"I think I'm just troubled by the fact that there doesn't seem to have been any movement since the last time we heard this presentation," said board member Monica Tibbits-Nutt.

The T estimates that with buses running every hour and 15 minutes along eight routes roughly following existing transit corridors, the service would cost $3.5 million per year, a subsidy of $17.48 per trip. The "late night" weekend service, which was eliminated earlier this year because of cost concerns and restricted ability to conduct repairs on subway tracks, had a per ride subsidy of about $14.

Marc Ebuna, the co-founder of Transit Matters, which is pushing the proposal, said he hoped efforts to collect data would not slow down the proposal and said the best way to obtain accurate ridership data would be to launch a pilot.

Others at Monday's meeting, including Andrew Bagley from the Massachusetts Taxpayers Foundation, noted the T's far-from-finished efforts to close a multimillion-dollar structural deficit.