Work began in early 2023 to build the bridge one half at a time
SEATAC – A new, wider and longer South 216th Street bridge across Interstate 5 in SeaTac will open to both directions of traffic on Wednesday, June 5.
Construction crews working on the Washington State Department of Transportation’s State Route 509 Completion Project are nearly done building the northern portion of the bridge. The southern side of the bridge opened to westbound traffic on South 216th Street in December 2023, while eastbound traffic used a detour to cross I-5.
The longer South 216th Street bridge is needed to span additional lanes on I-5. These added lanes, currently under construction, will connect new on- and off-ramps between the future SR 509 expressway and I-5. The old bridge was 290 feet long, while the new bridge is 335 feet long.
In addition to being too short, the original South 216th Street bridge was outdated and unwelcoming for non-motorized travelers.
“The previous bridge’s sidewalks were too narrow for people who use wheelchairs and forced bicyclists merge with vehicle traffic to cross,” said Project Engineer Ward Anderson. “Replacing the bridge to accommodate the extra lanes on I-5 gave us an opportunity to create a bridge that serves the community better. It has dedicated bike lanes, ADA-accessible sidewalks and a new eastbound left turn lane onto Military Road South.”
Construction crews still have some work to complete after it opens to motorists. That includes installing curbs, gutters, finishing a sidewalk, final paving and permanent striping on the bridge and the surface streets on either side of it. This work will require ongoing single lane closures and at least two additional full road closures for the paving and striping.
SR 509 Completion Project information
The SR 509 Completion Project builds 3 miles of new tolled highway between I-5 and South 188th Street near the south end of Seattle-Tacoma International Airport. The new highway will be completed in stages. The portion currently under construction between I-5 and 24th Avenue is scheduled to open in 2025. The final stage will build the remaining 2 miles of the expressway between 24th Avenue South and South 188th Street. The entire project is planned for completion by 2028.
Puget Sound Gateway Program overview
The SR 509 Completion Project is part of WSDOT’s Puget Sound Gateway Program, which also includes the SR 167 Completion Project in Pierce County. Combined, the two completion projects finish critical missing links in Washington’s highway and freight network.