All eastbound lanes of State Route 518 near Sea-Tac International Airport will close Aug. 18-21 to remove a damaged girder on the 24th Avenue South bridge, the Washington State Department of Transportation says. The left lane of westbound SR 518 also will close during the first of two consecutive weekends of work.

Beginning at 9 p.m. Friday, Aug. 18, through 5 a.m. Monday, Aug. 21, all eastbound lanes will close between SR 509 and SR 99/International Boulevard. The left lane of westbound SR 518 will close near the 24th Avenue South bridge. A signed detour will be available for eastbound SR 518 traffic, but people should expect delays and consider alternate routes.

This work will affect people attempting to reach Sea-Tac airport from SR 509 or the Burien area, while those attempting to reach the airport from the Interstate 5 corridor should see minimal delays related to construction.

Eastbound SR 518 detour
Eastbound SR 518 traffic will detour around the closure using Des Moines Memorial Drive South, South 156th Way, South 154th Street and SR 99/International Boulevard to the eastbound SR 518 on-ramp. People leaving on flights or meeting someone at the airport this weekend should plan for extra travel time.

Bridge girder replacement
The 24th Avenue South bridge was struck in 2020 by an eastbound vehicle with an over-height load, severely damaging the girder.

Contractor crews working for the Washington State Department of Transportation will replace the damaged girder and rebuild the driving surface. The damaged girder will be removed Aug. 18-21 before a new girder will be lifted into place during a similar weekend closure of eastbound SR 518 Aug. 25-28. The 24th Avenue South bridge will remain closed to vehicle traffic, though a shoulder remains open to pedestrians and bicyclists throughout the project.