Pretty good. Although I think your subway lines go too far away from the city. Foxboro, Brockton, Framingham, basically anything outside 128/95 would be better served by high frequency commuter rail with local/express service. I agree with converting the Green Line D branch to an extension of the blue line via a new tunnel past Charles/MGH through the back bay, although I wouldn’t extend it past riverside. I’m also surprised you didn’t restore the A branch to Watertown.