CENTRAL CITY, Colo. (CBS4) – A rockslide that occurred Tuesday afternoon kept all lanes of the Central City Parkway closed overnight.

There is no estimate when the road will reopen, partly because engineers haven’t been able to reach the area to assess the damage.

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The parkway is one route casino patrons use to reach Central City from Interstate 70. Another route, Highway 6 through Black Hawk, is now the alternative.

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Crews need to assess the stability of the hillside before they can begin moving the rocks.

Debris, some of it bus-sized, slid across all four lanes. One lane reopened Tuesday night for emergency vehicles.

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The road is private, so state funds won’t be used to clear the road.