A proposed Red-Blue connector would link the Bowdoin and Charles Street MBTA stations. Image courtesy of MassDOT.

North Shore residents, activists and elected officials filled an MBTA board meeting Monday, planning to demand the agency support a rail connection between the Red Line and Blue Line rather than the pedestrian walkway that had been floated.

Transportation Secretary Stephanie Pollack beat them to it. At the start of the meeting, before public comment even began, Pollack announced that the agency’s long-term plan for projects to be completed by 2040 would include a subway extension connecting the lines, not a walking path.

If it’s ever built, the link in question would have significant effects on the region’s transportation infrastructure, allowing Blue Line commuters to access job centers in Cambridge and Somerville – and Red Line commuters to reach East Boston and Lynn – without needing to walk or use a third line to transfer. With development booming in East Boston and along Revere Beach, the Blue Line was the only MBTA line to see ridership rise last year. The proposed initial phase of HYM Investment Group’s planned Suffolk Downs development includes 1.39 million square feet of residential, office and commercial space alone, out of a proposed 10.5 million square feet at full build-out.

“This is music to our ears to hear this will be included in Focus40,” said Boston Transportation Commissioner Gina Fiandaca, referring to the MBTA’s long-term plan. The Red-Blue connector “is a critical link serving East Boston, Cambridge and beyond.”

Approached by reporters after the meeting, new MBTA General Manager Steve Poftak declined to offer more details on the Red-Blue connector and its future.

“I hesitate to put any kind of timeline on any of these projects at this point in time,” he said.

Transportation leaders have for decades discussed an extension that would link the two. A connection was agreed upon as environmental mitigation for the Big Dig construction project, but the project was never fully designed and was dropped in 2015.

The Fiscal and Management Control Board did not take any action on the connector Monday beyond Pollack’s announcement. But board member Brian Lang said he was “absolutely convinced” it warranted prompt investment.

“It’s urgent for the city and the region,” he said. “I think the state should never have abandoned it.”

Pollack warned that Monday’s update did not guarantee success for the Red-Blue connector. The Focus40 plan, which is approaching a final draft, takes a long-term view unconstrained by finances, so funding has not yet been identified for included items. “Next Priorities,” where the connector was placed, is the second of three tiers in the plan.

“Inclusion in ‘Next Priorities’ does not mean we have the financial wherewithal to build them all and certainly not all at the same time,” Pollack said. “This is a 20-plus year plan.”

Transit Matters, the advocacy group leading the charge to build the Red-Blue connector, said it is pushing to have the project included in the MBTA’s five-year Capital Improvement Plan, which will be next revised in April. The MBTA recently estimated the work could be done for $200 million.