full limited-access freeway for the remainder, but updated preliminary plans would upgrade it to a four-lane divided highway, with right-in/right-out at Tiger Mountain and a diverging diamond interchange at I-90. While SR 18 has been a part of most I-605 proposals, it only bypasses the Greater Seattle area on the southern and eastern sides. See also List of future auxiliary Interstate Highways List of Interstate Highways in Washington References Further reading External links 05-6 (Washington) Transportation in Seattle Cancelled highway projects in the United States 05-6 (Washington)