The 22-24 inches of snow which fell in Pittsburgh on February 5-6 has obscured news of a colossal 113-car runaway derailment on CSX in Meyersdale, PA.

30-40 cars on the ground is a big derailment; 113 is just about a record.

The eastbound 130-car loaded coal train was descending Sandpatch Hill when dynamic and automatic braking became ineffective. The speed at the point of derailment was estimated to be 65 mph. The two locomotives and first eleven cars remained on the track. There were no injuries.

Build-up of snow between the wheel treads and brake shoes is one possible explanation; ice blockage in the brakepipe is another possibility.

Speed control is a matter of balancing forces: A 130-car train composed of 130 ton cars produces an accelerating force of 169 tons on a 1% descending grade. To prevent rising speed, an equal, opposing retarding force must be applied (stopping the train requires additional force). The maximum dynamic braking effort of just two six-axle locomotives, maybe 60-75 tons at best (10-12.5Klbs/axle), was clearly inadequate to control this train’s speed on a steep grade.

The kinematic model also helps explain the situation: Ignoring deductions for rolling resistance and windage effects, a train of any length or mass will accelerate at 0.219 miles-per-hour-per-second on a 1% descending grade.

The multi-billion dollar Positive Train Control program will do nothing to prevent overspeed derailments resulting from loss of braking capacity in mountainous territory. Despite introduction of two-way EOTM’s and tighter control over operating practices, there are still an average of a half-dozen or so runaways in mountainous territory each year.

 

PV

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