Mount Baker Tunnel

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The Mount Baker Tunnel carries Interstate 90 under the Mount Baker neighborhood of Seattle, Washington. It is actually twin tunnel bores, one completed in 1940 (rehabilitated in 1993) and the other completed in 1991. The official length is 1440 feet[1], though driving through you will notice the length is closer to a kilometer because of a cut-and-cover "lid" between the western portal and the beginning of the actual tunnel under the Mount Baker ridge. The eastern end of the tunnel links to the I-90 floating bridge on Lake Washington.

At 63 feet (19 meters) in diameter, it is the world's largest diameter soft earth tunnel, having been bored through clay.[1][2][3]

[edit] References

  1. ^ a b Preliminary List of Nationally and Exceptionally Significant Features of the Interstate Highway System (US DOT)
  2. ^ WSDOT historic bridges
  3. ^ Alaskan Way Viaduct and Seawall Replacement - Frequently Asked Questions (see What experience does WSDOT have with building tunnels?)

Coordinates: 47.590283° N 122.295427° W


Bridges and Tunnels in and around Seattle
Road bridges: Alaskan Way Viaduct | Ballard Bridge | Evergreen Point Floating Bridge | First Avenue South Bridge | Fremont Bridge | George Washington Memorial Bridge (Aurora Bridge) | Homer M. Hadley Memorial Bridge (Third Lake Washington Floating Bridge) | Lacey V. Murrow Memorial Bridge (I-90 Floating Bridge) | Magnolia Bridge | Montlake Bridge | Ship Canal Bridge | South Park (14th/16th Ave) Bridge | Spokane Street Bridge | University Bridge | West Seattle Bridge
Rail bridges/trestles: Salmon Bay Bridge | Wilburton Trestle
Tunnels: Battery Street Tunnel | Great Northern Tunnel | Mercer Island Lid | Metro Bus Tunnel | Mount Baker Tunnel
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