Explosive charges go off Tuesday on the bridge that used to carry the Pennsylvania Turnpike across the Allegheny River near Oakmont. The bridge was demolished and is being replaced by twin spans.

PITTSBURGH — A nearly 60-year-old bridge that once took the Pennsylvania Turnpike across the Allegheny River near Pittsburgh was demolished Tuesday.

The bridge was taken down with 200 pounds of explosives. Traffic on the Turnpike was stopped for about a half-hour during the demolition.

Twin spans are replacing the bridge. One already is open and carrying both directions of Turnpike traffic.

Officials said the demolished bridge fell safely into the river. Two surviving sections over land will be destroyed later this month.