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Re: Recent derailments - NTSB says Metro North too fast for curve 82 MPH
Author: SP5103
Date: 12-02-2013 - 21:44
> <> Approximately 6 seconds before the rear engine
> came to a stop, the throttle went to idle.
>
> <> Approx 5 seconds before the engine came to a
> stop, pressure in the brake pipe dropped from 120
> psi to 0 - which resulted in max braking.
>
> <> We do not yet know the initiating event for the
> throttle going to idle or the brake pressure
> dropping to 0 psi.
Something still isn't quite right here. The throttle went to "idle" from what - power? The air shot from 120# only 5 seconds before it stopped? The 120# brake pipe pressure is unusual, and shouldn't have resulted in any additional braking effort. It would take some time to develop "maximum braking", so the engine went from about 84 mph to a stop in only 3-5 seconds, that is one hell of a jolt and it would have been the derailed cars providing most of the stopping power! Assuming an average speed of 40 mph (between 80 and stopped), the train would be traveling about 60 feet per second on average. I am guessing that the derailment is what blew the air and tripped the PCS to drop the throttle. Was the engineer so incompetent, distracted or suffering from a medical condition, because I don't think he took any action to stop or slow the train. The whole overspeed issue is a surprise, and just adds to the confusion. There still is a possibility of a mechanical failure, or the controls not responding as expected and the engineer letting the situation get well past the point of no return.
> came to a stop, the throttle went to idle.
>
> <> Approx 5 seconds before the engine came to a
> stop, pressure in the brake pipe dropped from 120
> psi to 0 - which resulted in max braking.
>
> <> We do not yet know the initiating event for the
> throttle going to idle or the brake pressure
> dropping to 0 psi.
Something still isn't quite right here. The throttle went to "idle" from what - power? The air shot from 120# only 5 seconds before it stopped? The 120# brake pipe pressure is unusual, and shouldn't have resulted in any additional braking effort. It would take some time to develop "maximum braking", so the engine went from about 84 mph to a stop in only 3-5 seconds, that is one hell of a jolt and it would have been the derailed cars providing most of the stopping power! Assuming an average speed of 40 mph (between 80 and stopped), the train would be traveling about 60 feet per second on average. I am guessing that the derailment is what blew the air and tripped the PCS to drop the throttle. Was the engineer so incompetent, distracted or suffering from a medical condition, because I don't think he took any action to stop or slow the train. The whole overspeed issue is a surprise, and just adds to the confusion. There still is a possibility of a mechanical failure, or the controls not responding as expected and the engineer letting the situation get well past the point of no return.
