Seattle’s Alaskan Way Viaduct will be closed this weekend for a twice-yearly inspection.

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Both directions of State Route 99 will close between South Spokane Street and the north end of the Battery Street Tunnel from 6 a.m. to 6 p.m. Saturday and Sunday.

The closures are conducted every March and October so engineers can closely inspect the viaduct.

Drivers will need to take an alternate route during the closure and should expect possible delays in the area.

WSDOT said it’s possible the inspection will be finished early.