SR 509 I-5 Expressway and ramps
The following section describes some of the key features of the project. The designs presented are conceptual. The design-builder will finalize the schedules and designs, which may vary from the conceptual designs.
Building the first mile of the SR 509 Expressway and the ramps that will connect I-5 to the SR 509 will require major construction in SeaTac. WSDOT’s contractor will:
- Build the first mile of the SR 509 Expressway between 24th Avenue South and I-5 and the electronic toll point (near South 210th Street).
- Build a new I-5 overpass near South 212th Street. The overpass will connect northbound I-5 to northbound SR 509.
- Build a new southbound I-5 off-ramp just south of Military Road South
- Build a new southbound SR 509 ramp that will connect southbound SR 509 to southbound I-5.
- Connect the new ramps to Veterans Drive and the SR 516 interchange
Our contractor will develop specific plans for constructing the northbound SR 509 overpass. However, their plans to build an overpass instead of an underpass reduces impacts to the traveling public. The overpass eliminates the need for I-5 closures and lane shifts that were part of the original designs, which included building I-5 bridges that the new SR 509 would travel under. More specific information about overpass construction will be provided at a construction open house in late 2021 or early 2022.
Please share any questions or comments on this part of the project on the comments and survey page.