The westbound Riverside (91) Freeway will be completely closed Friday night between Corona and Anaheim Hills as part an ongoing improvement project, and motorists are advised to map out alternate routes ahead of time.

Beginning at 11 p.m. Friday and continuing until 5 a.m. Saturday, all westbound lanes on the 91 between the Corona (71) Expressway and Highway 241 will be shut down, according to the Riverside County Transportation Commission.

The agency said the closure is required to remove signage connected to a 91 corridor expansion project that’s nearing completion.

A four-mile stretch of the freeway will be out of service. Motorists are advised to consider exiting the 91 at the 71 interchange and taking the expressway north to the Pomona (60) Freeway, then turning south on the Orange (57) Freeway, which intersects westbound 91 on the Orange County side.

RCTC officials warned of possible significant travel delays for anyone trying to head west on the 91 through Corona and into Orange County Friday night.

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