From The Seattle Times:
http://seattletimes.nwsource.com/html/politicsnorthwest/2013399990_leaders_still_have_the_hots_to.html
The state is still eyeing building High Occupancy/Toll Lanes on Interstate 405. The idea has merit: the money just doesn’t exist for a full expansion of the freeway. Remember too this is the ONLY route to the biggest employers in Washington, with nothing other than express buses (also on the same road) connecting to it.
At least this way there would be a better HOV network to use (the current lane is overwhelmed at rush hours), with the option to pay a small fee to drive by yourself. This would also be similar to toll lanes in other parts of the country.
More:
http://www.wsdot.wa.gov/tolling/eastsidecorridor
http://www.pugetsoundtransportation.com/its/
Ben