From SDOT, shared in the interest of the many West Seattleites who drive through SODO:

Royal Brougham Way is now closed east and westbound between 4th Ave S and Occidental (map). The closure will continue through to late Saturday, April 4. A signed detour will guide motorists. Pedestrian access will be provided on S Royal Brougham Way. The closure is necessary so crews can relocate utilities and prepare for bridge pier construction for the SR 519 project