I had the pleasure of returning to the city in 2015 for a brief bit of work with my current company and was utterly blown away at the transformation of the boulevard, the green spaces, the visual beauty...and just the sense of openness and lightness. I felt like I could breath easier just walking down the street.
It's a shame to have had to overpaid so dearly for that, but what an amazing result. It was a great city before, but this just felt next-level.
I see it as flushing away a huge amount of technical debt that we had incurred over the last 100 years, hopefully setting us up for modernization on many fronts - which is quite a big deal when you consider it's competing to be a top tech hub.
For point of comparison, the population of Boston is around 700k, and the per capita income is 33k. That's... $23 billion.
I support infrastructure projects, and at this point think we should consider the Big Dig a learning experience and not a political punching bag. But can we really say it's a success, considering the countless other uses of the money that we had to pass on?
Edit: I don't think it's disingenuous, though. People genuinely do get confused about the difference between what a thing really is and what a thing is officially called.
It was expensive, but so are lots of other projects and practices. How many unnecessary & duplicative military bases do we operate in the South?
The new underground freeway is a waste. Twenty billion dollars were buried for a road that does little for outer suburb traffic and nothing at all for Boston. The best thing would have been to knock down the Central Artery and replace it with nothing at all.
Or we could have had a North Station-South Station connector. You could have that as a cheap cut-and-cover subway for 1% the price of the Dig. You could find a way to demolish the new City Hall along the way; that hideous thing has to go. It would be a bit slow and have a turn or two at that price but would be fantastic for transit service.
When it's paid for by taxes, you have the corporations who can now hire people from outside the city more easily, the tourism industries, and other entities that are actually reaping the most from the project paying for a proportionally larger amount than your average driver. Not only is that more fair, that the only way such a project could ever get funded.
"Here's this nice shiny new road, it's yours for free! All you have to do is pay $500/month in car expenses to use it. For Free!"
And improving one road requires further improvements to other roads as traffic increases due to induced demand. City streets (and parking) is extremely expensive to improve, so after you spend billions of dollars to feed cars into downtown more efficiently, how do you address downtown congestion and parking?
Those in the suburbs (of which I was one) drive to train/subway stations on the outskirts and take those in. You'd be an absolute fool to try to drive into the mess of one-way streets that is downtown Boston unless you have a really good reason.
Buses make good feeders to trains, but aren't so good for main routes. If you want people to use transit, it needs to be usable.
BRT is a good compromise.
I've done a cross-town bus commute and that was a good commute, the bus was crowded, but tolerable for 15 - 20 minutes. But then I moved and tried a longer distance bus commute from the suburbs to work, but didn't stick with it as it took 45 minutes longer than driving (30 minutes by car, 75 minutes by bus), and dropped me off a 15 minute walk from work. I could bike in about the same amount of time as taking the bus. A road accident meant that the bus could take even longer since it had to sit in the same traffic.
My current commute is much farther by miles, but shorter by time because I now live where I can take a train. Limited stop express trains are great. Full grade separation would be even better (to reduce delays due to accidents), but taking the train is faster than driving so I wouldn't even consider taking the car.