There was a rib failure in the #54 ramp. It broke past the anchorage of the split set bolts about 6"" to 12"" in an area about 18"" in length. No one was working in the area. The failure didn't go into the back, didn't impede ventilation, didn't impede foot traffic. Safety foreman notified Boise Field Office when he found out about the failure 1st thing Monday morning 7/17/06.