Alaskan Way was a busy 4 lane road prior to the seawall replacement project and SR-99 construction, the two addes lanes are dedicated for busses.

Really wish we had kept rail along this alignment (rather than letting Seattle Art Museum destroy the waterfront trolley), but short of that we are stuck with making busses fast and reliable.

Wrt cutting this down to 1 lane in either direction for regular cars, in the context of the ferry queues clogging Alaskan Way currently, narrowing the road would create a waterfront parking lot between ferries.

Running the park down the middle of the road would be enjoyable, Portland has a few nice parks of that style

Portland also entirely replaced our waterfront highway with an enormous park, probably not the precedent you're looking for.

https://en.wikipedia.org/wiki/Harbor_Drive

Out of curiosity, why is this not a good precedent? Were the results bad, or because it's Portland?

This freeway removal project was generally considered a success, I know I rather enjoyed the benefits of the new waterfront park in Portland when I was younger. Lots of good memories!

Not a good precedent as far as "We can't remove this road entirely". Road entirely removed, everyone was happy.

What I've seen on my commute (ferry terminal to South Lake Union) is that with the viaduct closed, there were much fewer trips (the ferries were very empty), but a lot more congestion on surface streets.

It's always hard to say what's needed, but I suspect the tunnel will be well used.

Seattle's waterfront is a bit different from Boston's but the Big Dig which was a much more complicated predecessor of this project was well worth it. I have been very critical of the Rose Kennedy Greenway for a variety of reasons but it is so much better than the hulking monster that was the Central Artery.