I-5 - SR 161/SR 18 Triangle Improvements - Phase 1 Completed 2012

A map showing work that was completed at the I-5/SR 18 interchange in 2012.

Overview

In 2012 we completed phase 1 of improvements to the area where Interstate 5, State Route 161 and SR 18 connect in Federal Way. During this phase, we:

  • Built a two-lane flyover ramp connecting westbound SR 18 to southbound I-5 and rebuilt the westbound SR 18 to northbound I-5 ramp to accommodate the new flyover ramp.
  • Built a new eastbound SR 18 to northbound I-5 flyover ramp and rebuilt the eastbound SR 18 to southbound I-5 ramp to accommodate the new flyover ramp.
  • Constructed a new exit ramp connecting the westbound SR 18 to southbound I-5 flyover ramp with SR 161 at S. 359th Street.

How you benefit

  • Improves safety: Improvements to the I-5, SR 161 and SR 18 interchange eliminates weaving (merging) by removing two cloverleaf loop ramps, reducing the number of side-swipe collisions.
  • Improves environment: To manage stormwater runoff crews built and rebuilt four detention ponds, redesigned a 500-foot stream and turned a 30-foot stream into a 400-foot long, fish-friendly, meandering creek. The project includes 22 wetland sites.

Funding

  • 2005 Gas Tax (Partnership Funding) - $100 million
  • 2003 Gas Tax (Nickel Funding) - $3 million
  • Existing Funds -  $687,000
  • Other Agency Funds - $8.8 million (federal funds)
  • Total Funding From All Sources - $112.5 million