Commuters who take Interstate 5 through Federal Way can expect delays as a summer-long project gets underway Tuesday.
The ramp from Weyerhaeuser Way to westbound state Route 18 will close Tuesday for about three months as crews prepare for one of two new flyover ramps as part of the $112 million Triangle project.
Drivers will follow a four-mile detour from eastbound Route 18 to the West Valley Highway and back to westbound Route 18.
About 4,300 people drive through that area daily, according to the state Department of Transportation.
While the ramp is closed, WSDOT crews will rebuild and elevate the ramp 20 feet to make room for a flyover ramp that will connect westbound SR 18 to southbound I-5.
The Triangle is named for the intersection of I-5, Route 18 and Route 161, also called Enchanted Parkway South, which is one of the most dangerous chokepoints in South King County.
A second flyover ramp will also be added from eastbound Route 18 to northbound I-5 in an attempt to ease congestion and stop the weaving drivers must do to navigate the interchange.
The project is slated to wrap up in late 2012.
But first, drivers must endure three ramp closures this summer.
The next one is scheduled for August, when the ramp from westbound Route 18 to northbound I-5 will shut down so crews can connect it to the rebuilt Weyerhaeuser Way ramp.
The last closure will take place from July 15-18 when crews will connect sections of the new flyover ramp to Route 18 and I-5. The ramp from eastbound Route 18 to southbound I-5 will be closed during that time.
Crews will begin installing large steel bridge girders over I-5 and Route 18 in the fall, which will mean nighttime closures.