New flyover ramps taking shape in Federal Way

Looking at two of the bridge columns that
 will support the steel tub girders over I-5.
By guest blogger Mike Murphy

It's not often that we build a new bridge over the freeway, but this weekend we're doing just that.

Crews are starting the final major milestone of a two-year project that aims to improve traffic and safety at the busy I-5/SR 18/SR 161 interchange in Federal Way. When all is said and done later this summer, drivers won't have to contend with the notorious weave as they jockey for position on the I-5/SR 18 ramps.

But it's no small task. For the next three weekends -- Friday and Saturday nights -- two huge cranes will lift the “steel tub girders” up and over I-5 and place them onto bridge columns that have been sprouting up alongside I-5. (They're called steel tub girders for obvious reasons; they resemble giant steel bathtubs.)

We'll need to completely close one direction of I-5 while the work is being done. Southbound I-5 will be closed near SR 18 the nights of  Feb. 10, 11 and 24. We'll close northbound I-5 the nights of Feb. 17, 18 and 25.

During the southbound I-5 closures traffic will be detoured onto Highway 99 and rejoin I-5 at 54th Avenue East in Fife. It's about a five-mile detour.

The northbound I-5 detour will send traffic onto eastbound SR 18 to Weyerhaeuser Way and back to I-5. You'll want to allow extra time for your late night trips during the closures. Roughly 7,000 vehicles use this stretch of I-5 on a typical weekend night. (Check the project website for detour maps.)

The girders will support the roadway for the two new flyover ramps -- one between eastbound SR 18 and northbound I-5, and the other from westbound SR 18 and to southbound I-5. Once they're in place we can begin to pour the pavement for the new ramps.

So what’s the benefit of a flyover ramp?

Anyone who travels between I-5 and SR 18 is probably familiar with the white-knuckle weave as they merge from one freeway to the other. It’s due to the cloverleaf interchange that was built in the 1960s. It was considered state-of-the art at the time but as the population grew, it quickly became obvious that it couldn’t handle the increasing traffic volumes.

The flyover ramps will completely eliminate the weave, and let drivers "fly" up and over I-5.

Funding for the $112 million project came from a combination of state gas taxes and federal grants.