Amtrak train was traveling at twice the speed

An Amtrak train in Philadelphia was traveling at more than 100 miles per hour, over twice the speed limit, when it entered a curve in the tracks and derailed, killing seven people and injuring more than 200, federal investigators said
While the precise cause of Tuesday night’s crash remains to be determined, experts from the National Transportation Safety Board (NTSB) believe the derailment would have been prevented by installation of an advanced safety system called “positive train control,” NTSB board member Robert Sumwalt said.
The engineer of the New York City-bound passenger train applied the locomotive’s emergency braking system just after entering the curved stretch of track, where the maximum allowed speed is 50 miles per hour (80 km per hour), Sumwalt said.
But the brakes managed to only slightly slow the train to 102 mph from 106 mph (171 kph) before the locomotive and all seven passenger cars derailed, he said.
Authorities have offered no explanation for why the locomotive was traveling at more than double the authorized speed.