Disaster appears to have started somewhere between alliance, ohio, and the derailment in east palestine. surveillance video of the train in alliance shows no signs of sparks coming from its wheels. there is a detector in seabring, ohio, that would indicate overheat, a so-called hot box detector. it's unclear if it detected any overheat. but in salem, ohio, just 13 miles further along, surveillance video clearly shows sparks in bright lights coming from under a rail car at about the half by the way point of the train. there's another hot box detector just down the track from where the surveilla...