or how much advanced notice either of the engineers had before they knew that this could possibly end with this collision, but how long would they need to prevent it? how much distance would they need to prevent it? >> a lot. it takes -- for a regular, you know, a normal configured train, this one is probably about ten cars, this particular train usually is, it takes at least a mile. if the train was going 55 miles an hour, it would take at least -- at least a mile to slow and probably more to stop that train and that translates, obviously, at 60 miles an hour, at least a minute or so to do it. and, again, it's dark. as many have said, it's a rural area and close to a large city, columbia, but it would have been tough to see. so they couldn't have stopped quickly and the passengers didn't say there was any braking before the collision.