MP: 27.23 Location: SR 509 and S 128th St, Burien Reassurance shield after the S 128th St exit   MP: 28.25 Location: S 112th St and SR 509, Seattle Reassurance shield after the S 112th St exit   MP: 28.69 Location: SR 509 and SR 99, Seattle JCT SR 99 coming up. There is a … Continue reading State Route 509, SR 518 to SR 99