When train 32N passedthe next HBD, at MP 69.01, the bearing’s recorded temperature was 103°F aboveambient. The third HBD, at MP 49.81, recorded the suspect bearing’s temperature at253°F above ambient.
Though trending up, the bearing temperature was within non-critical limits until shortly before the wreck occurred. It was about 46 miles between the last detector and the one that alerted just before the accident.
The train engineer increased the dynamic brake application to further slow andstop the train. During this deceleration, an automatic emergency brake applicationinitiated, and train 32N came to a stop.
After being alerted to the unsafe condition, the crew seemed to respond appropriately by slowing down to stop, but during that process derailment further back in the train must have separated the air hoses causing the emergency braking application.
This suggests that the crew didn't throw the train into emergency as some had suggested.
The positive train control system was enabled and operating at thetime of the derailment.
No other trains were involved, but this system is intended to prevent multi-train collisions or crews inattentively passing stopped signals. It indicates that the crew was alert enough to be following inputs within the confines of the system.
Train 32N was traveling about 47mph at the time of the derailment, which was less than the maximum authorizedtimetable speed of 50 mph.
So we know it wasn't speeding as some had alleged.