I agree with much of what you wrote (and gave you an upvote) but when you got to this part - The best thing for the Central Artery would have been just like the

I agree with much of what you wrote (and gave you an upvote) but when you got to this part - The best thing for the Central Artery would have been just like the Embarcadero Freeway; tear it down and replace it with nothing. - I have to disagree emphatically. Removing the Central Artery and replacing it with nothing only makes sense if the purpose of the new Artery was to move local traffic. It isn't, the primary purpose of I-93 is moving traffic from NY to CT to RI, through Boston up into NH and ME. Part of the traffic tie-ups on the old Artery were caused by locals using the highway as s shortcut to get from the North End to the South End, so in a sense the Big Dig did do as you suggest in that they removed a bunch of on/off ramps that make it difficult for local users to use, and replaced them with lower capacity surface roads (as well as green space + walkways). The Big Dig also included a bunch of transit improvements (some of which are why the MBTA is in a big hole right now, but that's another post). As for making traffic worse, 10 years after the opening, traveling from Woburn to Braintree is now a 20 minute trip during peak hour where it used to be 90 minutes in off-hours. Of course transit should be factored into roadway expansion, and in the case of the Big Dig, it was.