To reduce congestion, construction crews will widen the southbound Interstate 5 off-ramp at South 320th Street in Federal Way.

Drivers can expect occasional weeknight ramp closures during construction, according to the Washington State Department of Transportation (WSDOT). Construction is expected to be finished by the end of September.

Both city and WSDOT crews began work on the project this week. The off-ramp will be expanded from three lanes to five lanes. The finished project will feature two left-turn lanes and three right-turn lanes for vehicles entering South 320th Street from southbound I-5.

More than 15,000 vehicles use the off-ramp each weekday, according to WSDOT. South 320th Street is Federal Way’s main east-west route and serves 47,000 vehicles each day. The I-5 off-ramp at South 320th Street is often congested on weekday afternoons.

At a cost of $5.1 million, the project is funded by a federal grant along with $1.9 million from city funds, according to WSDOT.

Triangle Project

WSDOT crews are also building flyover ramps at I-5 and State Route 18 as part of the Triangle Project. All major work is expected to be finished by late fall 2012. Expect detours and closures for SR 18 exit ramps throughout the summer. Click here to learn more about these closures.