On Tuesday night, Amtrak train number 188 derailed outside of Philadelphia, leaving seven people dead and hundreds injured. The train entered a curve at more than 100 miles per hour — twice the posted speed limit — and investigators are now working to find out why. Some experts stress that human error should only be part of the conversation; aging infrastructure has long been a concern for financially-troubled Amtrak, and many are wondering if this tragedy could re-energize efforts to improve U.S. rail safety and put more resources behind U.S. infrastructure projects elsewhere. We explore the deadly Amtrak derailment and its aftermath.