Why the T needs to get cracking on the Green Line extension: $760 million in federal funds could be at stake

Paul McMorrow explains the rock and the hard place: On the one hand, the T is legally required to extend the Green Line to Somerville and Medford, at a cost now approaching $1 billion. On the other hand, shaky finances and any construction delays could jeopardize $760 million in federal funding for the project, leaving the state to figure out how to make up the difference.