It's not quite that cut and dried.

The 9 cents goes to a large number of road projects all around the
state.
Some of it is earmarked as "seed money" for the Viaduct and the 520
bridge, but not a dime of that state money will be spent on either of
those projects unless King County residents come up with a way to tax
ourselves for the balance of the money (a few billion)
before 2007.

There has not been a final decision about tunnel vs. elevated structure
for the viaduct.

You may not drive on the viaduct or the 520 bridge or the viaduct, but
look around wherever you live at whatever you've got. "If you've got
it, a truck brought it."
Those two structures are keystones in our statewide transportation
system.
Assuming you shop at WalMart, a whole heap of the stuff you buy is
unloaded from Chinese and Korean ships on the Seattle waterfront and
trucked to your local community. Even if you never drive across the 520
bridge or the viaduct, a whole lot of the commerce and economic
vitality for the entire state flows along those highways.

Here's an interesting exercise you might consider. Add up all the
local, county and state taxes collected in your county. You should be
able to find the numbers pretty easily.
Then compare the total local, county, and state expenditures in your
county. Unless you live in King, Snohomish, or Pierce County you will
see that the total expenditures in your county exceed the total taxes
collected. Only the three most populous counties actually "export"
taxes, so don't be taken in by the radio rabble rousers trying to
increase tension between the red and the blue counties. (This is one of
the reasons that the bill to split off Eastern Washington and make it a
separate state got *nowhere* in the legislature this year) :-)

Don't leave the state, I've been lots of other places and its worth a
few tax dollars to stay here, IMO. :-)