In just over a week, a new foam-supported Highway 99 bridge near South Spokane Street will be done, allowing traffic to be restored to two lanes each direction.
The Washington State Department of Transportation (WSDOT) is aiming for March 14 to finish the $18 million, 470-foot crossing, where southbound cars currently are limited to one lane during construction. Afternoon traffic congestion often results.
A decaying wood trestle, built in 1959, is being replaced by a concrete girder bridge, whose landings rest on concrete-encased blocks of white Geofoam, similar to a Highway 99 section one mile north. The dense foam is 1/20th the weight of rock or dirt fill, WSDOT says. The bridge spans a freight rail track.
Overnight closures in both directions are planned next week to tie the north- and southbound roadbeds together, and to paint lane stripes. The ramp from the West Seattle Bridge to northbound Highway 99 will also close. Shutdowns are scheduled from 9 p.m. to 5 a.m. on Monday, Tuesday, Wednesday and Thursday nights next week.