"Boston city proper had a 2008 estimated population of 620,535" 22,000,000,000$ / 620,535 = 35,450$ per person, for something they helps in some areas but made

"Boston city proper had a 2008 estimated population of 620,535" 22,000,000,000$ / 620,535 = 35,450$ per person, for something they helps in some areas but made congestion worse in others. The presumption is that the artery is only being used by Boston residents. It's used by Boston residents to get out the city, by other MA residents to get into the city, and by non-MA residents to get in & thru the city, as well as delivering goods received in Boston ports to points north, south and west. Freight rail can (and does, vis the huge CSX yard in Allston) move a huge portion of that load, but you're still going to have trucks for the last-mile delivery to the industrialized areas in EMass. (and where has it made congestion worse?) But even if you want to put everyone on buses, those buses still have to drive on something - the old artery couldn't be that something because it was falling apart, and alternatives have the same problem as an alternative highway system does. IOW. you're still talking about a tunnel system.