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<blockquote data-quote="Box Ox" data-source="post: 5522647" data-attributes="member: 48469"><p>Interesting additional info from the NTSB report.</p><p></p><p>Sounds like the crew wasn't being negligent in not stopping the train as the bearing temperature was rising. They just hadn't hit Norfolk Southern's temperature threshold of 170 degrees over ambient that would trigger an audible alarm from a hot bearing detector until they hit the detector at milepost 49.81 at 253 degrees above ambient. When that happened the crew took immediate action. But it was too late.</p><p></p><p></p><p>"Train 32N had 149 railcars, and 1 distributed power locomotive</p><ul> <li data-xf-list-type="ul">This included 20 placarded hazardous materials tank cars transporting combustible liquids, flammable liquids, and flammable gas, including vinyl chloride.</li> </ul><p>Train 32N was traveling about 47 mph at the time of the derailment, which was less than the maximum authorized timetable speed of 50 mph</p><p></p><p>Train 32 was operating with a dynamic brake application, The wayside defect detector, or hot bearing detector (HBD), as the train passed a wayside defect detector on the east side of Palestine, Ohio, at milepost (MP) 49.81 transmitted a critical audible alarm message instructing the crew to slow and stop the train to inspect a hot axle.</p><p></p><ul> <li data-xf-list-type="ul">Train 32N passed three HBD systems on its trip before the derailment.</li> <li data-xf-list-type="ul">At MP 79.9, the suspect bearing from the 23rd car had a recorded temperature of 38°friend above ambient temperature.</li> <li data-xf-list-type="ul">When train 32N passed the next HBD, at MP 69.01, the bearing’s recorded temperature was 103°friend above ambient.</li> <li data-xf-list-type="ul">The third HBD, at MP 49.81, recorded the suspect bearing’s temperature at 253°friend above ambient.</li> </ul><p>NS has established the following HBD alarm thresholds (above ambient temperature) and criteria for bearings:</p><ul> <li data-xf-list-type="ul">Between 170°friend and 200°friend, warm bearing (non-critical); stop and inspect</li> <li data-xf-list-type="ul">A difference between bearings on the same axle greater than or equal to 115°friend (non-critical); stop and inspect</li> <li data-xf-list-type="ul">Greater than 200°friend (critical); set out railcar"</li> </ul></blockquote><p></p>
[QUOTE="Box Ox, post: 5522647, member: 48469"] Interesting additional info from the NTSB report. Sounds like the crew wasn't being negligent in not stopping the train as the bearing temperature was rising. They just hadn't hit Norfolk Southern's temperature threshold of 170 degrees over ambient that would trigger an audible alarm from a hot bearing detector until they hit the detector at milepost 49.81 at 253 degrees above ambient. When that happened the crew took immediate action. But it was too late. "Train 32N had 149 railcars, and 1 distributed power locomotive [LIST] [*]This included 20 placarded hazardous materials tank cars transporting combustible liquids, flammable liquids, and flammable gas, including vinyl chloride. [/LIST] Train 32N was traveling about 47 mph at the time of the derailment, which was less than the maximum authorized timetable speed of 50 mph Train 32 was operating with a dynamic brake application, The wayside defect detector, or hot bearing detector (HBD), as the train passed a wayside defect detector on the east side of Palestine, Ohio, at milepost (MP) 49.81 transmitted a critical audible alarm message instructing the crew to slow and stop the train to inspect a hot axle. [LIST] [*]Train 32N passed three HBD systems on its trip before the derailment. [*]At MP 79.9, the suspect bearing from the 23rd car had a recorded temperature of 38°friend above ambient temperature. [*]When train 32N passed the next HBD, at MP 69.01, the bearing’s recorded temperature was 103°friend above ambient. [*]The third HBD, at MP 49.81, recorded the suspect bearing’s temperature at 253°friend above ambient. [/LIST] NS has established the following HBD alarm thresholds (above ambient temperature) and criteria for bearings: [LIST] [*]Between 170°friend and 200°friend, warm bearing (non-critical); stop and inspect [*]A difference between bearings on the same axle greater than or equal to 115°friend (non-critical); stop and inspect [*]Greater than 200°friend (critical); set out railcar" [/LIST] [/QUOTE]
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