Three lanes will soon become five at the southbound Interstate 5 off-ramp to South 320th Street in Federal Way.

Crews working for the Washington State Department of Transportation (WSDOT) and the City of Federal Way will begin construction this week on a project to widen the ramp and make other safety improvements. More than 15,000 vehicles use this ramp each weekday.

“This ramp leads to the city’s downtown core, but it’s a frequent chokepoint, especially on weekday afternoons,” said Cary Roe, Federal Way’s public works and parks director. “This project will improve safety and ease congestion for commuters and shoppers alike.”

South 320th Street is a major east/west route that serves 47,000 vehicles each day. Without these improvements, engineers estimate that traffic could regularly back up onto I-5 in just a few years.

Drivers can expect occasional weeknight ramp closures during construction.

The existing three-lane ramp will be expanded to five lanes, including two left turn lanes and three right turn lanes. Crews will widen the ramp to the west and build a retaining wall to support the hillside. The crosswalk across the southbound I-5 on-ramp will be relocated to the north side of South 320th Street and crews will build a pedestrian island in the middle of the new crosswalk.

Crews also will upgrade lighting and modify signal timing to keep traffic moving.

This $5.1 million project is funded by the City of Federal Way and a federal grant. WSDOT engineers designed the project and are overseeing the construction, which is expected to wrap up by the end of September. For more information please visit www.wsdot.wa.gov.

This is one of two projects that will improve access to and from I-5 in Federal Way. Just south of South 320th Street, crews are building two new flyover ramps at the I-5/SR 18/SR 161 interchange. More information on that project can be found at www.wsdot.wa.gov/projects.