The new I-5 Steilacoom-DuPont Road interchange will fully open to two-way traffic Saturday, March 21. See below for additional information.
Project overview
This project is intended to help relieve chronic traffic congestion and improve mobility along Interstate 5 near Joint Base Lewis-McChord. Crews will rebuild the Steilacoom-DuPont Road (Exit 119) interchange and extend I-5 HOV lanes to Mounts Road.
What to expect
New Steilacoom-Dupont Road overpass fully opens March 21
On the heels of opening the new southbound I-5 exit 119 to Steilacoom-DuPont Road, crews are making final preparations to fully open the state’s third diverging diamond interchange. The new I-5 overpass will provide access between DuPont and Joint Base Lewis-McChord. Demolition of the old overpass is currently scheduled for April 3-4, and will require two overnight full closures of both north and southbound I-5.
Overnight work to open the new overpass
At 8 p.m. Friday, March 20, the southbound I-5 exit to Steilacoom-DuPont Road will close. At 6 a.m. Saturday, March 21, the new Steilacoom-DuPont Road on-ramp to southbound I-5 will open. At that time, crews will close the 1957 overpass to all traffic. Northbound I-5 travelers using exit 119 will begin using the new interchange.
Additional information is available via the online open house.
Some of the work needed to fully open the new diverging diamond interchange could be delayed due to rain, snow or cold weather. Travelers can find real-time updates on the statewide travel map.
Overnight bridge demolition planned April 3-4
Overnight Friday and Saturday, April 3-4, both directions of I-5 will detour through exit 119 at Steilacoom-DuPont Road.
- Travelers will see lane closures on I-5 each night from 10 p.m. to 6 a.m. the following day.
- To keep travelers moving, law enforcement will direct traffic through the interchange.
- Travelers should allow at least 30 minutes of extra time to reach their destination. WSDOT encourages people to carpool or reschedule trips before or after work hours.
Once the original overpass is removed, crews can finish widening I-5 to extend the high occupancy vehicle (HOV) lanes. Those HOV lanes will open later this summer
Changes to Wilmington Drive and Barksdale Avenue intersection
When the former Steilacoom-DuPont Road overpass closes, crews will create a three-way intersection north of the old railroad crossing.
The traffic lights will be removed. Travelers will see three new stop signs at the Wilmington Drive and Barksdale Avenue intersection.
Other changes include:
- A new sidewalk that connects Wilmington Drive to Steilacoom-DuPont Road for people walking or rolling to or from Barksdale Station.
- The addition of a left turn lane into Barksdale Station, and the removal of the existing concrete median curb.
- Dedicated left turn lanes to and from the Historic Village.
Travelers can expect to see flaggers occasionally alternate traffic during daytime hours at this intersection.
Crews will work overnight this spring to pave the new three-way intersection. They will also repave the road up to the new Steilacoom-DuPont Road roundabout.
Project overview
The I-5 Mounts Road to Steilacoom-DuPont Road Corridor Improvements project is expected to be complete late 2026.
The $240 million project is part of a suite of improvements as part of the I-5 Mounts Road to Thorne Lake Corridor Improvements project. The previous improvements:
- Rebuilt the Berkeley Street and Thorne Lane interchanges, which include improved access for people who walk, bike and roll.
- Added new HOV lanes and auxiliary lanes in both directions of I-5.
The project will add HOV lanes to both directions of I-5.
Crews will rebuild the Steilacoom-DuPont Road interchange. The new interchange will connect to Steilacoom-DuPont Road near Pendleton Avenue. Workers will replace the existing at-grade railroad crossing. Crews will build a new bridge. It will carry travelers over the tracks.
This project is the third in a series of projects that widen I-5. The work creates new HOV lanes. After this project is complete, both directions of I-5 will have HOV lanes between Mounts Road and Gravelly Lake Drive.
New overpasses are necessary to add lanes. This is the case for the existing overpass at the Steilacoom-DuPont Road interchange.
The existing overpass was built in 1957. It is classified as "poor condition". It does not meet current vertical clearance standards from I-5.
A new interchange will be built to current design standards and allow for new HOV lanes in both directions of I-5.
Traffic flow is slowed due to the current distance between each interchange. Other factors include JBLM’s DuPont Gate, the railroad, and the intersection of Wilmington Drive and Barksdale Avenue.
Environment
On June 30, 2021, the U.S. Department of Transportation Federal Highway Administration issued a Finding Of No Significant Impact (FONSI) for the Interstate 5 JBLM Congestion Relief Project Revised Environmental Assessment (PDF 31MB).
WSDOT has published the I-5 JBLM Vicinity Congestion Relief - South Study Area Supplemental Environmental Assessment (PDF 61.84MB).
This document was prepared as a supplement to the 2017 Environmental Assessment (EA) for the project's North Study Area. The Supplemental Environmental Assessment (SEA) describes the South Study Area and cover the potential environmental effects related to transportation, noise, natural resources, parks and recreation, community resources, and other resources.
The South Study area is located between the vicinity of the Mounts Road (116) and Main Gate (120) exits.
For links to the 2017 EA, please refer to the Environment tab on the I-5 - Mounts Road to Thorne Lane I/C - Corridor Improvements webpage.
