Boston, MA - After introducing a money-saving, bare-necessities revision Monday, the Green Line Extension project got a tentative green light, but must secure federal approval and meet additional conditions before moving full-speed ahead.

That, and it could still hit the brakes, if necessary. The MBTA and Massachusetts Department of Transportation boards took a first look at the revised, roughly $2.3 billion plan for the long-awaited Somerville-to-Medford extension Monday.

Although it scales back certain aspects, the revised GLX still involves the construction of six new stations and relocation of the current Lechmere stop. Given the time it takes to fully staff the extended line and complete construction, the finished Extension is at least five years out, according to estimates presented at Monday's hearing. READ MORE: MBTA Releases Revised, $2.3 Billion Green Line Extension Proposal

Cambridge, Somerville Promise Green Line Extension $75 Million

Subscribe here for free Boston news alerts Despite slim hopes of an up or down vote Monday, the MBTA and MassDOT boards first forwarded the project to the Federal Transit Administration, awaiting its stamp of approval before formally moving ahead. The boards also voted to begin work on a new finance plan and project management system in interim.

Additionally, board members made clear the project could yet be axed, should it come in above budget. There remains real concern that, despite community pleas to extend the line, the MBTA already has enough trouble maintaining its current infrastructure.

"I don't think it's the most important thing for the MBTA to be doing in the next three years," Transportation Secretary Stephanie Pollack said of the Green Line, according to The Boston Globe.

The project is also still above-budget.

At a projected cost of $2.3 billion, the revised plan saves some $700 million, but still goes $300 million over the original Green Line Extension budget. To save money, the new proposal scales back plans for the new stations and an accompanying bike and pedestrian path. To close the multimillion-dollar funding gap, the Boston Region Metropolitan Planning Organization hopes to reallocate $152 million in federal highway funds, and MassDOT has received a $75 million pledge from Somerville and Cambridge combined. That leaves roughly $73 million unfunded.