Federal Railroad Administration, Office of Safety Headquarters Assigned Accident Investigation Report HQ-2007-53, Iowa Chicago and Eastern Railroad Company, Manona, Iowa, September 26, 2007

摘要

On September 25, 2007, at 7:15 p.m., CDT, an eastbound Iowa Chicago & Eastern (ICE) manifest freight train, Train Symbol MMCMQ-25, operating at a recorded speed of 20 mph, derailed 27 cars, the 27th through 53rd from the head-end. The derailment occurred on the ICE Rail System, Mason City Subdivision at milepost (MP) 10.7, which is 3.6 miles east of Monona, Iowa, in Clayton County. Train Symbol MMCMQ-25 consisted of 4 locomotives, all on the head-end, 108 cars (72 loads and 36 empties), was 6,532 feet in length, and 10,514 tons. The train was being operating by a two person crew (engineer and conductor). There were no injuries as a result of this derailment and no hazardous materials were involved. Cost estimates are: track $771,633, equipment $627,131. FRA mandatory required post accident drug/alcohol testing was not performed though the damage estimates far exceed the $1 million threshold. The weather at the time of the derailment was cloudy and 57F. The probable cause of the derailment was restricted snubbing on Car No. ICE 50015, which created insufficient damping, allowing load springs to be driven solid creating a condition favorable to harmonic rocking and/or poor curving. This harmonic rocking caused the B-end, L3 wheel to climb the high rail of a curve. A probable contributing factor was insufficient side bearing clearance which also created a condition favorable to harmonic rocking and/or poor curving.