Alaskan Way Viaduct Emergency Traffic Management and Closure Plan

The Alaskan Way Viaduct is a 2.1-mile, double-deck highway running along Seattle's central waterfront. It is a vital part of the region's transportation system, carrying over 100,000 vehicles per day. The Viaduct and supporting seawall were severely damaged in the 2001 earthquake and need to be replaced.

The Emergency Traffic Management and Closure Plan for the Viaduct is a collection of four scenario-based action plans developed should the Viaduct be forced to close down prior to replacement. The plan does not restore capacity of the Viaduct. A full or partial closure means moving high volumes of vehicles to alternate routes, many of which are not designed for significant additional capacity to absorb that traffic.

Detours have been chosen for a variety of factors, including their connectivity to SR 99, the number of travel lanes, and their ability to accommodate large trucks and transit. These are not the only routes available for use. However, for route continuity and to guide unfamiliar motorists, these specific detours will be signed and marked.

To learn more about the Emergency Traffic Management and Closure Plan, you can access portions of the Plan and other information here:

Scenario files are large and may be slow to download. Thank you for your patience.

Diagram of Vulnerabilities of the Viaduct and Seawall