From an article on Viaduct politics (by Knute Berger in Crosscut), one of my comments on another comment:
You speak with certainty that "The work would stop all use of the Viaduct during the construction period..."
I'd like to remind you that that was NOT the case with the Spokane Street Viaduct. Obviously, without question, it is possible to do major construction while such a structure is being used — we have just done it. Is there a cost? Is there annoyance? Of course but it clearly made sense on the SSV.
I could challenge every one of your other vague and undocumented assertions. But I won't because, alas, i don't believe that facts are at issue.
You think it is worth some vast and unknown amount of money and environmental impact to take down the Viaduct.
I have a different set of values and priorities focussing on the sort of civic interventions illustrated (literally) by my book City Comforts.