from a MassDOT press release I just received:
The Green Line Extension Project (GLX) wanted to inform you of emergency overnight work scheduled for tonight and continuing possibly through the weekend.
GLX Construction activities at the School Street Bridge in Somerville interrupted power yesterday, June 24. Though power was restored yesterday, it is Eversource's intent to work around the clock from 5PM this evening until the power lines are repaired. This work will be done in conjunction with the School Street Bridge work & lane closure which began in April 2015 and should not require a full road closure.
Thank you in advance for your cooperation and understanding. This work is an important step in bringing the Green Line from Cambridge to Medford and Somerville. Should you have any questions please feel free to contact the Green Line Extension at 855-GLX-INFO (459-4636) or info@glxinfo.com.