The Port of Seattle was the lead agency in a coalition of the Freight Mobility Strategic Investment Board (FMSIB), the Union Pacific Railroad (UPRR), Prologis, and the City of Seattle with a task to build a dedicated one-way truck-only roadway to provide a safer and faster truck freight route from the Port's marine terminals to the UPRR Argo Yard rail gate. The overpass was a necessary improvement for cargo-hauling trucks. Before construction for the project was completed, these trucks were required to enter State Route 99, cross three lanes of south-bound traffic to reach the turn lane onto Diagonal Ave. South, and then wait for a signal to cross northbound SR 99.
The new southbound truck-only roadway now provides direct access from the east side of the SR 99/East Marginal Way trestle underpass to the existing Colorado Avenue South cul-de-sac. This project also made improvements to Colorado Avenue South and Diagonal Avenue South from the southern end of the new truck roadway to SR 99/East Marginal Way.
The East Marginal Way Phase II segment of the project included street improvements along East Marginal Way and to the under-crossing of the SR 99 structure south of Duwamish Avenue at the north end of the Argo Yard Truck Roadway. Washington State Department of Transportation (WSDOT) and the Port of Seattle were responsible for this portion of the project.
The Argo Yard Truck Roadway project included three elements:
- Element I: The Port of Seattle maintained a 1300-foot long, 16-foot wide southbound dedicated truck-only roadway between the SR 99/East Marginal Way trestle underpass and the existing Colorado Avenue South cul-de-sac.
- Element II: The Port also improved the public roadway and railroad crossing along Colorado Avenue South and Diagonal Avenue South.
- Element III: UPRR constructed a new automated gate system to improve efficiency for processing freight at its Argo Yard.
- Improved safety
- Improved air quality by reducing delay-related idling of trucks
- Increased efficiencies in intermodal and multimodal activity
- Further complemented major freight roadway improvements in the area
- Increased the overall roadway capacity
- Incorporated and supported public/private partnerships
- Eliminated the last grade crossing conflict in area for a northbound route to East Marginal Way overpass
Construction was completed in April 2015.