>> brandon was always much more quiet, soft spoken, very caring when he spoke to people. very considerate of other people's feelings and interactions he would have. >> bostian graduated from the university of missouri in 2006. he became an amtrak engineer four years after landing a job as a conductor. >> and the accident now raising more questions about the safety of america's railways because get this, there's actually technology out there available that could have stopped this crash. that's what investigators tell us. why wasn't it on the track. >> matt gutman show us this hi-tech system. >> the troubling images of another train derailing. ten cars spilling off the track in pittsburgh. in south carolina, this train on truck collision and in wisconsin a locomotive catching fire. no one was hurt but they're reminders of tuesday's deadly accident in philadelphia which the government says could have been prevented with existing technology called positive train control or ptc.