OK, that's a fair point. The majority of the value was probably locked up in a small number of hands. I think some probably was spent on materials and services local to the project. Maybe some of the revenue went into expansion for some of the companies working on the contract? But besides being a one-off boondoggle, was there a net negative negative to the tunnel? Had the tunnel not been built then would that money would have stayed locked up in a single place? The money being spent on services and construction generated more economic activity than it sitting in a bank.

I dont think it's a two choice thing. The options aren't to keep the money in the bank vs build this specific tunnel. Its a bigger question, why not this vs. Other income producing infrastructure that has a longstanding, consistent return. Like a interstate highway improvement project.