I-90 to highway 99 (Seattle: trains, stadium, rated)

[Seattle4321]

Do you guys think it's possible or would be a good idea to make 1-90 with 1 or 2 lanes each direction in a tunnel to highway 99. It could take demand off 1-5 and put more use to 99. Sometime in the future do you think this would could happen? Also assuming that 509 gets expanded to connect with i-5 south of the aiport.

[Polymorphist]

Honestly I think what's going to happen eventually is that another level will be added over I-5 through downtown. Or they'll tunnel it. They can't really expand it (but then, never say never, I guess), so I think this is what they'll do at some point.

More rapid transit which is separated from roads would be better.

[CrazyDonkey]

I-90 already connects to I-5. Connecting a tunnel from I-90 to the Viaduct Tunnel, when it is finally completed, would not add sufficient benefits to justify the cost. You can just drive from the I-90 exit at 4th Avenue S to the entrance to SR 99. I do think that connecting SR 520 via tunnel (under I-5) with the north end of the Viaduct Tunnel might be worth considering.

The capability of expanding I-5 is limited, due to the constraints imposed by the Convention Center. There was talk some years ago about building a north-south freeway in east King County. Seattle, due to its geography and politics, is limited in how many more lanes/cars can be crammed into it.

I agree with Polymorphist that building out the light-rail system has the best chance of making it easier to get into and out of downtown. The Downtown Transit Tunnel is capable of handling four-car trains at 1.5-minute headways. Currently they are running two-car trains at 7.5- to 15-minute headways.

[sean98125]

It's already easy to get from 90 to 99. I think there are only two stoplights near the stadium to get through. Probably not worth the money to build a tunnel to bypass two stoplights.