The Massachusetts Bay Transit Authority will soon learn if its strategy for containing the ballooning costs of the Green Line extension is working when it receives bids from three companies for the multibillion dollar project’s largest contract.

And in an unusual twist, the agency is asking the bidders to revive parts of the project that were unceremoniously dumped in 2016 in the face of a billion-dollar overrun, such as canopies over train stops, and the final 3,000-foot stretch of a bike and walking path to be built alongside the rails.

As part of picking the contractor, the T said it will score bidders on their offers to restore up to six optional features that were previously eliminated — so long as they don’t push the value of the contract beyond the T’s maximum rate of $1.3 billion.

“These things are all desirable, but we didn’t want to add these things back right away,’’ said John Dalton, the T executive overseeing the Green Line extension. “So long as the market says we can afford it, we can add them back in.’’

The bids are due Thursday, setting off an elaborate review and scoring process that will culminate with the T’s awarding the contract in November. The project will extend the Green Line from Lechmere, up through Cambridge and Somerville and into Medford. It is expected to begin service in December 2021.

The three finalists for the contract — each a joint venture of either local, national, or global engineering and construction companies — either declined to comment or did not respond to requests for comment.

To avoid a repeat of earlier cost overruns, the design and construction contract will include a provision that sets a maximum price at $1.3 billionas well as tighter MBTA oversight of the construction, T spokesman Joe Pesaturo said.

The Baker administration was forced to recast the Green Line extension, reducing or eliminating some components, and firing contractors after the original cost estimate soared to nearly $3 billion in 2015.

The cutbacks reduced the total projected cost to $2.3 billion, which includes the construction work, the cost of real estate and new Green Line cars, and other work.

The MBTA has listed up to six optional features bidders can propose, but they must do them in the following order: weather canopies for the seven new stations, additional elevators for passengers with disabilities beyond the six already required, public art, an additional access point to the walking-biking path, and restoration of the 3,000-foot segment of the path from Washington Street in Somerville to Lechmere station that was dropped. The sixth and final option is to expand a maintenance facility for trolleys that was reduced in size during the budget cuts.

Randal Thurston, a Somerville artist whose contract for an installation at one of the stations was canceled in the 2015 cost cutting, said the MBTA recently notified him the job might be restored, depending on how the contracting process shakes out. But he said that none of the bidding companies have contacted him yet to discuss pricing and design.

“There is so much that has to do not just with the artwork being considered, but also how much it’s going to cost,’’ Thurston said. “There are a lot of layers to understanding how this would work. That part of the conversation is elaborate, and there hasn’t been any contact. So I’m doubtful.’’

Lynn Weissman, cochair of Friends of the Community Path, said the entire bike and pedestrian path should be built as part of the Green Line project, no matter what the contractors bid.

Her group also hasn’t been contacted by any of the contractors, but she’s at least glad the path and other seemingly doomed parts have a lifeline — for now.

“We hope that one way or another the state will be able to get all of these things done,’’ she said.

Adam Vaccaro can be reached at adam.vaccaro@globe.com. Follow him on Twitter at @adamtvaccaro.