Last Part of I-5 Improvement Project Aims for Fall Finish

April 2, 2026 - West Edition #7
Lori Tobias – CEG Correspondent

Washington State Department of Transportation photo

During November 2025, construction crews finished pouring the concrete driving surface of the new I-5 Steilacoom-DuPont bridge over the railroad tracks.

The project —- the third in a series of projects to widen I-5 — includes the construction of a new overpass at exit 119.
(Washington State Department of Transportation photo)

The last 17 girders for the new Steilacoom-DuPont overpass were set the week of Sept. 15, 2025.
(Washington State Department of Transportation photo)

Each girder was 156 ft. long and weighed up to 171,000 lbs. Each one was delivered through the city of DuPont at night while flaggers and law enforcement stopped traffic as needed along the route. (Washington State Department of Transportation photo)

A worker assists the bridge deck concrete pour on I-5 over Pendleton Avenue near Joint Base Lewis-McChord in June 2025. (Washington State Department of Transportation photo)

The new bridge is being built
in sections on I-5 to provide
additional clearance for
vehicles traveling on
Pendleton Avenue.
(Washington State Department of Transportation photo)

Crews worked over two weekends to set and place 13 bridge beams over Interstate 5 in early April 2025. (Washington State Department of Transportation photo)

Crews installed 13 girders over Interstate 5 during April 2025. The girders make up the backbone of the new I-5 overpass that will connect the city of DuPont and Joint Base Lewis McChord. (Washington State Department of Transportation photo)

The final portion of a multiphase effort to combat congestion on a busy stretch of Washington's Interstate 5 is under way and on target for completion in late fall 2026.

The $240 million I-5 Mounts Road to Steilacoom-Dupont Road Corridor Improvements project is next to Joint Base Lewis-McChord, one of the largest military installations on the West Coast.

"We are diligent in working with Joint Base Lewis-McChord to make sure they understand what's happening and what their needs are, so we can take care of the take care of the people who are taking care of our country," Doug Adamson, a spokesperson for the Washington State Department of Transportation (WSDOT) told Construction Equipment Guide. "A lot of this work has involved parts of the Interstate 5 access going onto Joint Base Lewis-McChord itself. In months, we're going to be rebuilding the gate, which serves so many soldiers, military contractors and other people who are going on to the base at that time. So, it's an awful lot of work."

The project — the third in a series of projects to widen I-5 — includes the construction of a new overpass at exit 119, which will be the third diverging diamond overpass in the state. The new overpass will allow for the creation of new HOV lanes. Once the project is complete, both north and south travel lanes of I-5 will have HOV lanes between Mounts Road and Gravelly Lake Drive.

Washington State Department of Transportation photo

The existing overpass was built in 1957. It is classified as "poor condition" and does not meet current vertical clearance standards from I-5. The design-build project was awarded to partners Guy F. Atkinson Construction and Jacobs Engineering Group.

Among the numerous challenges is keeping the interstate open, Adamson said.

"A lot of the work has really focused on keeping three lanes in both directions open the entire time as we rebuild this overpass," he said. "And really, when you're doing that type of construction in an area that has so many people, it's almost like building an airplane while you're flying it. This area has, on average, 134,000 vehicles a day, and that's a lot of people."

Another challenge is the notoriously wet Pacific Northwest weather.

"It is very difficult to keep this type of work going when you are working in soup, when you are working in that much mud," Adamson said. "Our design-builder, Atkinson, has done a very good job staging and has worked very diligently to keep the project moving. We are fully expecting to finish on time in late fall."

The new overpass opened in late March with the demolition of the old bridge scheduled for early April with overnight lane closures and detours in place. Once the original overpass is removed, crews will finish widening I-5 to extend the HOV lanes that will open later this summer, according to WSDOT.

Washington State Department of Transportation photo

Other work includes a newly completed three-way intersection north of the railroad crossing at Wilmington Drive and Barksdale Avenue. Future 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.

The I-5 Mounts Road to Steilacoom-DuPont Road Corridor Improvements project is part of a suite of the I-5 Mounts Road to Thorne Lake Corridor Improvements project. The previous improvements include:

• Rebuilding the Berkeley Street and Thorne Lane interchanges, which include improved access for people who walk, bike and roll.

• Adding new HOV lanes and auxiliary lanes in both directions of I-5.

"We are in the last final push to make significant upgrades to a large section of Interstate 5 in Pierce County," Adamson said. "Among all of these projects, we've done a lot to rebuild interchanges, to put in pedestrian improvements and for people who are bicycling and people who are in mobility assistance devices to get from one side of I-5 to the other. We've had chronic congestion through the area for years. In this this final Interstate 5, we're heading towards the goal line to get the project completed."

The I-5 corridor work is part of the $16 billion Connect Washington transportation revenue package approved by the Washington State Legislature in 2015. CEG

Lori Tobias

Lori Tobias is a career journalist, formerly on staff as the Oregon Coast reporter at The Oregonian and as a columnist and features writer at the Rocky Mountain News. She is the author of the memoir, Storm Beat - A Journalist Reports from the Oregon Coast, and the novel Wander, winner of the Nancy Pearl Literary Award in 2017. She has freelanced for numerous publications, including The New York Times, The Denver Post, Alaska Airlines in-flight, Natural Home, Spotlight Germany, Vegetarian Times and the Miami Herald. She is an avid reader, enjoys kayaking, traveling and exploring the Oregon Coast where she lives with her husband Chan and rescue pups, Gus and Lily.