The tunnel is such a waste of money. Is anyone going to seriously use it without any downtown exits? And isn't it also going to be tolled?
The vast majority of traffic on that stretch of 99 isn't going downtown. And now it's "gone."
That's not to say it's a perfect solution, or that there won't be related issues, but I lived in San Francisco after the quake knocked down the 101, which ran EXACTLY like the 99, straight through the most desirable stretch of Waterfront in the city, and was a fucking eyesore and a humiliating blot on the landscape.
The replacement there was worse in many ways - that is, they simply didn't replace it. So now all the traffic that used to thunder right past the waterfront, blocking the view, riddled with homeless and crime, was gone and replaced with a beautiful public space and moderated traffic that was 100% headed to destinations in that area. It was a fantastic improvement to the city, and the traffic simply adapted. More went up Van Ness, even more simply went across the Bay bridges. The Golden Gate area and Marin improved too.
This will fatten up the 5 corridor, North seattle to Seatac will be almost 100% 99 and 5 now, but coasting under and past, rather than straight through downtown. Sports games could be nightmarish? Hard to say.
But the waterfront improvement will be a jewel in our crown and be great for the city and the public. It will also shunt the homeless and drug addicts and their support structure, out of the area (as soon as we get rid of Murray who is encouraging them so he can build high rises in your leafy avenues) and hopefully become the beating heart of the city. Because the Seattle center is kinda weak.