The MBTA is looking into connecting the Red and Blue lines, again

A long-imagined idea would extend the Blue Line to the Charles/MGH Red Line stop. –Yoon S. Byun/Globe Staff

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

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.

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 them to move on.