Out with the old: New Steilacoom-Dupont Road overpass set to open in DuPont early 2026

DUPONT – If the weather cooperates, a portion of the new Interstate 5 interchange in DuPont will open by mid-January. Workers will also fully open the new roundabout in DuPont.

New overpass opens to southbound I-5 travelers

Once southbound travelers on I-5 begin using the new exit 119to Steilacoom-DuPont Road, they will notice a few changes. Those going to DuPont will turn right toward the new roundabout, while people heading to Joint Base Lewis-McChord will turn left and take the overpass.

People on northbound I-5 going to DuPont or JBLM will continue to use the existing exit and the 1957 Steilacoom-DuPont overpass.

The Washington State Department of Transportation will announce the exact date for the opening of the new interchange once it is scheduled.

Temporary changes to travel between DuPont and JBLM

When the new overpass opens, the older will close to southbound traffic. DuPont travelers will use the new Steilacoom-DuPont overpass to reach JBLM or northbound I-5. The old overpass will provide access from JBLM to DuPont or southbound I-5. For more information, please visit the online open house.

Coming spring 2026

The rest of the new overpass will open to two-way traffic as a diverging diamond interchange sometime in the spring. The interchange’s design helps traffic move more efficiently. The new overpass will also provide improved access for people to walk, bike or roll between DuPont and JBLM.

Crews will later demolish the 1950’s era overpass, which is classified in poor condition. It does not meet current vertical clearance standards for I-5. Removing the old overpass will require overnight lane closures. WSDOT will announce the dates once they are available

The demolition will allow crews to make final preparations for the opening of the latest I-5 HOV lanes between Mounts Road and Gravelly Lake Drive, which is scheduled for late summer 2026.

Project information

The I-5 Mounts Road to Steilacoom-DuPont Road Corridor Improvements project is expected to be complete in late 2026.

The $240 million project is part of a suite of improvements within the I-5 Mounts Road to Thorne Lake Corridor Improvements project. Previous improvements added new HOV and auxiliary lanes in both directions of I-5 and rebuilt the Berkeley Street and Thorne Lane interchanges, including improved access for people who walk, bike and roll. 

Travelers are encouraged to sign up for email updates for the project. Real-time traveler information is also available from the WSDOT app and the WSDOT statewide travel map.