Whidbey Island -> WA I-90 clinch?

[yakra]

May be driving east from Whidbey Island WA soon. The most direct choice would seem to be I-405, but the possibility of a WA I-90 clinch is too good to pass up.

What's the deal with the I-90 express lanes? If I make my entrance that way, is that still close enough in anyone's opinion to call it a clinch?
The CHM Hwy Browser shows I-90 proper taking the southern fork, towards WA519.

Do I want to try an approach via WA519? And isn't there demolition on the Alaskan Way Viaduct, that could complicate things?

[NE2]

What's the deal with the I-90 express lanes? If I make my entrance that way, is that still close enough in anyone's opinion to call it a clinch?
The CHM Hwy Browser shows I-90 proper taking the southern fork, towards WA519.

If you're anal, you can hop on at 519 and shift left to the express lanes at the tunnel: http://maps.google.com/maps?ll=47.589997,-122.304523&spn=0.005564,0.014173&gl=us&t=m&z=17&layer=c&cbll=47.589997,-122.304523&panoid=Ewej3c_3M8PueWbhyqGAYg&cbp=12,76.67,,0,-0.65

[Kacie Jane]

Unless you also want to clinch WA 519, the viaduct construction shouldn't effect you at all.  Getting on I-90 heading east, the terminus is at 4th Avenue & Edgar Martinez Dr (Atlantic St).  But personally, I'm not anal enough to care; I'd think that as long as you get on at one of the two downtown termini, it should count.

(P.S. Be aware that unlike the I-5 express lanes, for the most part, the I-90 express lanes are HOV only.)

[yakra]

Would Mercer St -> 99 -> 519 be workable?

[Alps]

May be driving east from Whidbey Island WA soon. The most direct choice would seem to be I-405, but the possibility of a WA I-90 clinch is too good to pass up.

What's the deal with the I-90 express lanes? If I make my entrance that way, is that still close enough in anyone's opinion to call it a clinch?
The CHM Hwy Browser shows I-90 proper taking the southern fork, towards WA519.

Do I want to try an approach via WA519? And isn't there demolition on the Alaskan Way Viaduct, that could complicate things?

I'd call it a clinch. The Express Lanes are part of the same interchange as the WA 519 end. Having just been on it, the ramp up from WA 519 feels like a ramp until it curves east into I-90, and that's right where the Express Lanes come in. Do your thing.

[Kacie Jane]

Would Mercer St -> 99 -> 519 be workable?

If your goal is to avoid viaduct construction, this would be the opposite of what you want to do. If all you want to do is clinch that westernmost mile of I-90, then you can actually get off at the I-90 exit from I-5 south and either take the Dearborn St ramp to the express lanes, or the 4th Ave ramp to the general purpose lanes.

[TEG24601]

I would consider I-5 to Idaho a Clinch, The 1500 ft to 4th or Martinez drive you don't need to worry about.

[Kacie Jane]

I would consider I-5 to Idaho a Clinch, The 1500 ft to 4th or Martinez drive you don't need to worry about.

No.

[KEK Inc.]

I-90 allows single-occupants between Seattle and Mercer Island, but you can't really get back onto the mainline easily once you're in the express lanes.  You're forced to exit at Mercer Is. unless you have a passenger.

[yakra]

Ended up approaching from the south instead.
Here's what I ended up doing.