This is a sharp reversal for the state, which was once required to build the Red-Blue connector as an environmental offset for the Big Dig highway project, but then lobbied for years to ditch the job. In 2015, the federal government finally allowed the state to move on.

The T will embark on a three-month study of the proposed Red-Blue connector, a long-imagined idea to extend the Blue Line from its terminus at Bowdoin Station to the Charles/MGH Red Line stop. The lines are the only two on the subway system that do not directly connect to one another.

After spending years trying to ignore the idea, state transportation officials are taking a fresh look at linking the MBTA’s Red and Blue lines.


Then along came Amazon.

After the online retailer initiated its search for a second North American headquarters, Boston mentioned the idea of connecting the two subway lines as part of its pitch for Suffolk Downs in East Boston, which straddles two Blue Line stops.

The bid said the Red-Blue connector was a “clear goal” of the state government. That was, at best, a charitable read of the situation, but it looks slightly more accurate now.

Amazon or no Amazon, Suffolk Downs is slated for a major redevelopment, and its developer, Tom O’Brien, has made clear the project would benefit from an easier connection to the Red Line.

Jeff Gonneville, the T’s deputy general manager, said the new study would look at whether ridership potential on a Red-Blue connector has changed in the last several years, and also update construction options since the last time the state studied building a 1,500-foot tunnel along Cambridge Street, at a cost of about $750 million.

The $50,000 study announced Monday will be conducted by the engineering firm VHB, according to MBTA spokesman Joe Pesaturo.


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