SEATTLE (AP) — Officials say the State Route 99 Alaskan Way Viaduct through downtown Seattle will close starting April 29, significantly affecting traffic for about two weeks.

The Washington State Department of Transportation said Friday the viaduct between South Spokane Street and the south end of the Battery Street Tunnel will be closed while the tunneling machine known as Bertha digs underneath the roadway.

Officials say about 90,000 vehicles a day use the viaduct so they’re anticipating major congestion on other roads.

Regional agencies have created a closure website called 99closure.org with resources and ideas to adjust commutes during the closure.

Closing the viaduct during tunneling will enable better monitoring of the structure and allow for quick repairs if any ground movement from tunneling occurs, officials said in a news release.

Bertha is building a double-decker traffic tunnel to replace the earthquake-damaged Alaskan Way Viaduct.

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