WASHINGTON – The speeding Amtrak train that crashed in Philadelphia last year, killing eight people, most likely ran off the rails because the engineer was distracted by word of a nearby commuter train getting hit by a rock, federal investigators concluded Tuesday. The National Transportation Safety Board also put some of the blame on the railroad industry’s decades-long delay in installing Positive Train Control, equipment that can automatically slow trains that are going over the speed limit. Engineer Brandon Bostian was apparently so focused on the rock-throwing incident he heard about over the radio that he lost track of where he was and accelerated full-throttle to 106 mph as his train went into a sharp curve with a 50 mph limit, investigators said at an NTSB hearing convened to pinpoint the cause of the May 12, 2005, tragedy. “He went, in a matter of seconds, from distraction to disaster,” NTSB board member Robert Sumwalt said. Bostian, who has been suspended without pay since the crash for speeding, did not attend the hearing.