The re-opening of Government Center station will officially reconnect the MBTA’s Green and Blue lines, meaning all five of the system’s major transit lines touch one another at some location. With one exception.

A connection between the Red and Blue lines has been an idea under consideration in some form since at least the early 1970s. Yet no current plan exists to build the fabled “Red-Blue Connector.’’

“If you had an alien coming from somewhere and studying our transportation system and looking at the MBTA, I think the first thing they’d notice is how come these two lines aren’t connected,’’ said Rafael Mares, a vice president at the Conservation Law Foundation.


Currently, those hoping to transfer between the Red and Blue lines must add additional stops — and time — to their commutes. They can take the Green line between Government Center and Park Street, the Orange Line between State and Downtown Crossing, or head out onto the street and walk the short distance.

The Red-Blue Connector was once part of a list of projects the state committed to as part of a legal agreement with the Conservation Law Foundation to mitigate against the traffic created by the Big Dig. But in 2006, the state got legal permission to downgrade its Red-Blue commitment to just the creation of a design. The design work was never completed, and in 2013, the state eventually received permission to drop the project all together, MBTA spokesman Joe Pesaturo said.

The MBTA has released drafts of potential plans, benefits, and costs of a Red-Blue Connector. One in 2010 proposed extending the Blue Line at Bowdoin station about 1,500 feet underneath Cambridge Street to connect with the Red Line at Charles/MGH. Preliminary estimates appraised the Connector at about $750 million and said it would take six years to construct.

It’s not the only option. Mares suggested the idea of a people mover between State Street Station to Downtown Crossing.


The disconnect isn’t just inconvenient; it creates heavier traffic along Green and Orange line stops already at capacity and worsens the efficiency of the transit system. In addition, it limits the ability of people to move smoothly between Cambridge and East Boston.

“There are two types of riders that do that,’’ Mares said. “One are people who are going to Logan Airport, and then the other are people who work in Cambridge, at Harvard for example, and live in East Boston.’’

Jim Aloisi, former state transportation secretary, wrote about the benefits of a connector in Commonwealth magazine last year.

“Most people do not have the luck or luxury to have purely linear origins and destinations,’’ he wrote. “Reflecting that reality, transit routes need to be aligned in ways that enable convenient and seamless movements through the transit system. Connectivity is the great virtue of world class transit systems.’’

But with the T in cost-cutting mode, and the lack of a legal requirement to complete it, the Red-Blue connector is a no-go right now.

“It’s a project that continues to exist and a really important idea. [But] I can’t tell you that there’s a movement around it right now,’’ Mares said. “The [Conservation Law Foundation] would definitely like to see that revived.’’

The aliens might, too.