Interstate 405 Washington

Interstate 405 Washington
History
North End
South End
I-405 north - Bellevue, WA

Interstate 405 north at Downtown Bellevue, Washington. 06/27/15

Overview

Interstate 405 provides a bypass to the east of Seattle, connecting with several major suburbs on the east shore of Lake Washington. The urban loop is the most direct route to Redmond, home of Microsoft, via the freeway along State Route 520. As a result of growth in the greater Seattle area, Interstate 405 carries significant traffic volume, almost on a level like I-405 in California, albeit with fewer lanes.

High Priority Corridor

Interstate 405 is part of High Priority Corridor 35: FAST Corridor.

History

The original proposal for Interstate 405 around greater Seattle was submitted to the American Association of State Highway Officials (AASHO) in a letter dated July 14, 1958.1 Initial stretches were designated as Washington State Route 405 between Renton and Tukwilla. The first section opened to traffic in September 1965. SR 405 was redesignated as I-405 with its completion by 1971.2

Route Information

  • North End – Lynnwood, WA

  • South End – Tukwila, WA

  • Mileage – 30.30

  • Cities – Tukwila, Renton, Newcastle, Bellevue, Kirkland, Bothell, Lynnwood

  • Junctions – I-5 I-90

Source: December 31, 2021 Interstate Route Log and Finders List

I-405 Annual Average Daily Traffic (AADT)

Source: 2017 AADT – WSDOT Traffic Data Geoportal

I-90/405 trailblazers on SR 518

State named trailblazers for I-5 and I-405 along the eastbound entrance ramp to SR 518 from Seattle-Tacoma International Airport (SEA). Photo by Jeff Royston (02/24/06).

SR 509 south at SR 518 - Burien, WA

SR 509 south at the eastbound on-ramp for SR 518 to Seattle-Tacoma International Airport (SEA) and I-5/405. Photo by Chris Elbert (03/03/06).

Highway Guides

North End I-5 Washington 525 – Lynnwood, Washington

I-405 North at I-5 SR 525

I-405 north at I-5/SR 525 - Alderwood Manor, WA

Interstate 405 weaves northward between the Alderwood Manor and Martha Lake communities 2.9 miles from SR 527 to SR 525 and I-5. 08/29/06

I-405 north at I-5/SR 525 - Martha Lake, WA

The unnumbered ramp for I-5 north departs next for Vancouver, British Columbia. 08/29/06

I-405 north at I-5/SR 525 - Martha Lake, WA

Interstate 5 heads north from I-405 at Martha Lake to Everett, Marysville and Bellingham. SR 525 extends the freeway northwest to SR 99 en route to Mukilteo. 08/29/06

I-405 north at I-5/SR 525 - Martha Lake, WA

The right lane drops at the loop ramp for southbound Interstate 5 to Lynwood and Seattle. Two lanes transition onto northbound SR 525. 08/29/06

I-405 north at I-5/SR 525 - Lynwood, WA

An end shield is posted for Interstate 405 along with a begin SR 525 shield. 08/29/06

I-405 north at I-5/SR 525 - Lynwood, WA

Interstate 5 angles southwest through Lynwood to Mountlake Terrace and Shoreline before reaching the Seattle city limits. 08/29/06

SR 525 South at I-5 I-405

SR 525 south at I-5/405 - Lynwood, WA

1.5 miles north of I-5 south and I-405 south on SR 525 at North Lynnwood. 08/29/06

SR 525 south at I-5/405 - Lynwood, WA

The next exit along SR 525 south is the connection for Interstate 5 southbound to Seattle. 08/29/06

SR 525 south at I-5/405 - Lynwood, WA

The entrance ramp from Alderwood Mall Parkway forms an auxiliary lane along SR 525 to I-5 south. 08/29/06

SR 525 south at I-5/405 - Lynwood, WA

Beyond the exit ramp to I-5 south, SR 525 transitions into Interstate 405. There is no access to I-5 north in this direction. 08/29/06

SR 525 south at I-5/405 - Lynwood, WA

Interstate 405 begins at the south end of Washington State Route 525 above I-5. 08/29/06

I-5 South at I-405

I-5 south at I-405/SR 525 - Martha Lake, WA

Interstate 5 advances south through a six-ramp parclo interchange (Exit 183) with 164th Street SW at Martha Lake ahead of I-405. 08/30/06

I-5 south at I-405/SR 525 - Martha Lake, WA

An HOV ramp passes overhead from the Ash Way Park and Ride Lot one mile north of Interstate 405. 08/30/06

I-5 south at I-405/SR 525 - Martha Lake, WA

Two lanes link I-5 south with Interstate 405 at Exit 182. Interstate 405 ostensibly provides a bypass of Seattle but instead comprises a crowded commuter route through Seattle’s eastern suburbs. 08/30/06

I-5 south at I-405/SR 525 - Martha Lake, WA

Interstate 405 runs along the east side of Lake Washington from Bothel south to Renton. There is no access to SR 525 north from I-5 at Exit 182. 08/30/06

I-5 North at I-405 SR 525

I-5 north at I-405/SR 525 - Lynwood, WA

Exit 181A connects I-5 with 44th Avenue W to SR 524 in Lynwood just ahead of Alderwood Mall and the systems interchange with SR 525 north and I-405 south. 08/30/06

I-5 north at I-405/SR 525 - Lynwood, WA

Exit 182 separates from Interstate 5 north in a half mile for SR 525 north to Mukilteo and I-405 south to Bothell and Kirkland. 08/29/06

I-5 north at I-405/SR 525 - Lynwood, WA

Exit 182 separates from Interstate 5 north for I-405 and SR 525. 08/29/06

South End I-5 Washington 518 – Tukwila, Washington

I-405 South at I-5 SR 518

I-405 south at I-5/SR 518 - Renton, WA

Interstate 405 south concludes at a directional cloverleaf interchange with I-5 and SR 518. 06/26/15

I-405 south at I-5/SR 518 - Tukwila, WA
I-405 south at I-5/SR 518 - Tukwila, WA

The ramp for I-5 north to Downtown Seattle includes access to adjacent Southcenter Boulevard and Westfield Southcenter mall. 06/26/15

I-405 south at I-5/SR 518 - Tukwila, WA

A left exit ramp links the south end of I-405 with the HOV lane along Interstate 5 north through Tukwila. 06/26/15

I-405 south at I-5/SR 518 - Tukwila, WA

A loop ramp connects I-405 with Interstate 5 south to Federal Way and Tacoma. SR 518 extends west along a freeway to SeaTac and Burien. 06/26/15

I-405 south at I-5/SR 518 - 2006

An end sign for Interstate 405 was formerly posted at the transition into SR 518 west. Photo by Chris Elbert (03/03/06).

I-405 south at I-5/SR 518 - Tukwila, WA

A loop ramp connects I-405 with Interstate 5 south to Federal Way and Tacoma. SR 518 extends west along a freeway to SeaTac and Burien. 06/26/15

SR 518 East at I-5 I-405

SR 518 east at I-5/405 - SeaTac, WA
SR 518 east at I-5/405 - Tukwila, WA

Leading east from Seattle-Tacoma International Airport (SEA) toward I-405, traffic on SR 518 increases to succeeding ramps for Southcenter Mall and Interstate 5. 06/24/15

SR 518 east at I-5/405 - Tukwila, WA

Construction in 2008 added a third eastbound lane along SR 518 ahead of the ramps for Interstate 5. 06/24/15

SR 518 east at I-5/405 - Tukwila, WA
SR 518 east at I-5/405 - Tukwila, WA

A left exit connects SR 518 east with I-5 north into Seattle. A lane drop occurs at the ramp for I-5 south to Tacoma while a single lane transitions onto Interstate 405 north to Renton. 06/24/15

I-5 North at I-405 SR 518

I-5 north at I-405/SR 518 - SeaTac, WA

Passing under South 178th Street, Interstate 5 advances one mile north to Exits 154A/B for SR 518 west and I-405 north. 06/24/15

I-5 north at I-405/SR 518 - Tukwila, WA

The ensuing exit along I-5 northbound links with parallel Southcenter Parkway at Westfield Southcenter mall. Exit 154 immediately follows for SR 518 and I-405. 06/24/15

I-5 north at I-405/SR 518 - Tukwila, WA

Passing under the Southcenter Parkway overpass in Tukwila, a lane drop occurs at Exit 154B for I-405 north to Renton. A high occupancy vehicle lane separates from the left while the I-5 northbound mainline continues with three lanes through the exchange. 06/24/15

I-5 north at I-405/SR 518 - Tukwila, WA

Traffic partitions along Exit 154 for I-405 north to Bellevue and SR 518 west to the SR 509 freeway at Burien. 06/24/15

I-5 South at I-405 SR 518

I-5 south at I-405/SR 518 - Tukwila, WA

The southbound HOV lane along I-5 separates from the freeway mainline just ahead of the wye interchange with SR 599. The exchange (Exit 154A) with Interstate 405 follows. 08/29/06

I-5 south at I-405/SR 518 - Tukwila, WA

Traffic from SR 599 south combines with I-5 just ahead of succeeding exits for Southcenter Boulevard, SR 518 west and Interstate 405 north. 08/29/06

I-5 south at I-405/SR 518 - Tukwila, WA

Exit 154B departs for both Southcenter Boulevard and SR 518 west to Sea-Tac International Airport (SEA) and Burien just ahead of the left exits for Interstate 405 north to Renton. 08/29/06

I-5 south at I-405/SR 518 - Tukwila, WA

Left Exit 154A merges with the inside lanes of SR 518 east to Interstate 405 ahead of Renton. 08/29/06

Sources:

  1. Washington State Highway Commission letter to AASHO, dated July 14, 1958, retrieved from AASHTO Route Numbering Archive.
  2. Interstate 405 (Washington). Wikipedia.org.

Page updated November 7, 2020.