> Seattle removed its waterfront viaduct from service for a couple of weeks before changing over to the new $3.3B tunnel and traffic was mostly fine, despite apocalyptic predictions of gridlock.

I think this is not really capturing the full impact. This could have been caused by people choosing not to travel as much, and we would have to measure the economic impact of the reduced travel. Are people not visiting local businesses because they decide to stay home?

Not saying you aren't correct, just that traffic levels are only one thing we need to look at.