No more waiting for trains, DuPont’s new interchange opens this weekend

You’re running out of time to drive the old Steilacoom-DuPont Road overpass of I-5. It’s scheduled to close for good Sunday morning, as the new interchange opens to all traffic.

Nearly three years of construction on the new interchange should wrap up early Sunday morning when the new overpass and on- and off-ramps open to traffic. The old overpass just doesn’t meet the needs of the growing communities in DuPont and around Joint Base Lewis-McChord (JBLM).

“The existing bridge doesn’t meet our standards,” Washington State Department of Transportation (WSDOT) spokesperson Doug Adamson said. “It dates back to 1957, and with the new addition of the overpass, it will be built to modern earthquake standards. So an awful lot of benefits for the community and those serving our country.”

The key feature of this new interchange is that it goes over the railroad tracks just north of I-5. That means traffic will no longer have to wait for the train.

“When this new overpass opens, traffic will no longer be going through an intersection that’s at grade or at the same level as the Sound Transit trains that are going through there,” Adamson said.  “We’ll be going up and over, through a brand new diverging diamond interchange.”

In preparation for opening the new interchange, WSDOT will close the southbound I-5 off-ramp to Steilacoom-DuPont Road at 10 p.m. Saturday until 6 a.m. Sunday, though that could change with bad weather.

“We’re going to keep our fingers crossed right up until the last minute,” Adamson said. “We’ll keep you posted and let you know.  The weather is something that we just can’t control.”

The work can be done Saturday night or Sunday night, too. That would simply postpone the interchange opening.

April closures will shut down I-5 in both directions

The bigger impact on drivers will be the first weekend in April. That’s when the old overpass is scheduled to come down. This could really impact the front end of spring break. Both directions of I-5 will be closed from 10 p.m. to 6 a.m. both Friday and Saturday nights during the demolition. All traffic will be diverted off the freeway at the new interchange.

“We’ll work to get all the people through there as best we can, but pardon our dust, there’s going to be a lot of construction during those two nights,” Adamson said.

Once the old overpass is removed, contractors can tackle the final piece of this project, which is extending the HOV lanes in the area.

“When that’s done, late this summer, we’ll have a brand new northbound HOV lane right there at Mounts Road as you come up through Nisqually, and then southbound, the HOV lane will extend to Center Drive,” Adamson explained.

Adding the HOV lanes should help ease congestion at the south end of JBLM, especially on Friday afternoons.

This completes the series of projects on the books from south of Tacoma through DuPont.

Up next: widening I-5 between Mounts Road south through Nisqually. This would likely include new bridges over the Nisqually River. The northbound span was built in 1937.

This project is still in early discussions. There is a lot of environmental work to do, and the project has not been funded.

Chris Sullivan is a traffic reporter for KIRO Newsradio. Read more of his stories here. Follow KIRO Newsradio traffic on X.

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