From the Seattle Department of Transportation:

The off-ramps to Harbor Island from westbound West Seattle Freeway and from southbound SR99 will be closed this coming weekend beginning Friday evening, September 9, at 7 p.m. The off-ramps will be reopened Monday morning, September 12, by 5 a.m. The closures are needed in order for the replacement of three railroad crossings at the south end of Harbor Island.

  • Motorists who are not in large trucks/commercial vehicles can detour by taking the high level West Seattle Bridge, using the Delridge Way exit, then taking the right onto Chelan Ave SW, another right onto SW Spokane St, and eastbound across the Duwamish West Waterway and back onto Harbor Island. 
  • Large trucks and commercial vehicles can take “official signed” detour route because it is primarily intended for large trucks that unable to use the detour described above. The signed will direct motorists to go south on East Marginal Way S, across the First Ave S Bridge. They will be directed to take the first exit after the bridge, looping them back onto northbound 2nd Ave S, and onto W Marginal Way SW. After passing underneath the West Seattle Bridge, they will be directed to take a left turn onto SW Spokane St, which will take them eastbound back across the Duwamish West Waterway and onto Harbor Island.

The railroad crossing work is part of the SDOT project currently repaving SW Spokane St from SW Klickitat Way to East Marginal Way S. The project, which began in August and is expected to take up to three months to complete. SDOT would like to thank the public for its patience while this work is being completed. More information can be found on the project website, located at: www.seattle.gov/transportation/pave_Spokane.htm.