South Pierce County I-5 Improvements

Washington State Dept. of Transportation provided an update regarding construction: Travelers who use Interstate 5 in south Pierce County can look forward to additional lanes and new overpasses. Beginning in October, design-build contractor Atkinson Construction will begin work to replace the Berkeley Street and Thorne Lane overpasses, and widen I-5 from milepost 120 near Joint Base Lewis-McChord (JBLM) to Thorne Lane in Lakewood.

Once complete, the number of northbound and southbound lanes on I-5 will increase from three to four in each direction. Additional auxiliary lanes will be constructed on northbound I-5 between Berkeley Street and Gravelly Lake Drive, and on southbound I-5 in two places — from Gravelly Lake Drive to Thorne Lane and from Berkeley Street to the JBLM main gate.

The new Thorne Lane and Berkeley Street interchanges will be grade-separated, or built a different height, from the existing rail line, reducing the potential of conflicts with trains. Both new interchanges will be built adjacent to their respective existing overpasses. New roundabouts and signalized intersections will help traffic flow through the area. The new Berkeley overpass will be one structure and the new Thorne Lane overpass will feature two bridge structures.

What to expect during the two-and-a-half year construction project:

  • Narrowed and shifted lanes on I-5 and ramps.
  • Overnight lane and ramp closures, some weekend ramp closures and one extended closure of the Berkeley Street on-ramp to northbound I-5.
  • Extended closure of Union Avenue at Thorne Lane.

The $243 million dollar I-5 Steilacoom-DuPont Road to Thorne Lane – Corridor Improvements project is expected to be complete in summer of 2021. WSDOT is hosting an open house 4:30 to 7:00 p.m., Thursday, Oct. 25 at the Tillicum Elementary School. This will be an opportunity for community members to learn about the construction schedule and the effect on traffic.

Contact: Cara Mitchell, WSDOT communications

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