Pennsylvania train crash highlights shortcomings of automated railroad braking system

The collision of three Norfolk Southern trains in Pennsylvania early this month highlights the shortcomings of the automated braking system that was created to prevent such crashes. That's because none of the circumstances the National Transportation Safety Board described Tuesday in its preliminary report on the March 2 derailment would have triggered the automated positive train control system to stop the trains. Railroad safety expert Chris Barkan said the system that was created after a deadly 2008 collision in California isn't designed to stop trains in these circumstances. The eastbound train that smashed into a stopped train had passed a restricted speed signal. But without a stop signal, the braking system wouldn’t have been triggered.