The local WALTHAM interlocking consisted of "Conrail Crossover" (two tracks going to single then back to two), with a couple of industrial spurs branching off. Both "ends" of the crossover were fully protected by searchlight signals. Despite the CTC machine most of the line was still run under rule 251 with the CTC being of the remote control only kind.
The brick B&M towers are solidly built and the MTBA has been kind enough to honor it with a historic plaque and several human interest pieces in local media so it is unlikely that WALTHAM faces demolition, but there will now no longer be any place in the Boston area where a lucky kid can get invited up to see a piece of history. I am unsure if this is the MTBA's last active interlocking station as the movable bridges on the Newburyport/Rockport Line used to control local switches and signals although that may have changed.
If you are interested in a full Railfan Guide to the WALTHAM area you can find one written by a Position Light Blog collaborator here.