Amtrak derailment, Kansas

[NP Eddie]

I agree---let's forus on the derailment and not a speech about employees that work on the train. How would you like to eat at McDonalds with only two employees, one taking orders and one cooking?

As information, my wife and I made a St. Paul-Whitefish roundtrip this week. Service was great!

Ed Burns

[mbinsewi]

I had heard on news reports that the engineer saw a displaced rail, and went in emergency breaking.  As I undertsand it, going into emergency breaking will cause a derailment.  Is this true?

Maybe I'm not fully understanding the dynamics of emergency breaking a fast moving train.

Mike.

[BaltACD]

mbinsewi

I had heard on news reports that the engineer saw a displaced rail, and went in emergency breaking.  As I undertsand it, going into emergency breaking will cause a derailment.  Is this true?

Maybe I'm not fully understanding the dynamics of emergency breaking a fast moving train.

Mike.

Derailments caused by emergency braking, when they happen, will happen in long freight trains (with a lot of slack) and will have secondary causes associated with train make up and the curve nature of the trackage where the emergency braking took place.  Emergency braking can create excessive buff (compressive) forces within the train and 'pop' a relatively light empty car over the outside rail in a curve with a heavy slack run in.  Conversly, if for some reason (physical characteristics of the track) high draft (stretching) forces get created in the train with emergency braking, it is possible for a portion of the train to be 'stringlined' through curves and thus derail.

The only Amtrak train that has sufficient length for either of these scenarios to enter the picture is Auto-Train and it doesn't operate through territory that has the necessary degree of curvature for these scenarios to play out.

[cefinkjr]

mbinsewi

I had heard on news reports that the engineer saw a displaced rail, and went in emergency breaking.  As I undertsand it, going into emergency breaking will cause a derailment.  Is this true?

Maybe I'm not fully understanding the dynamics of emergency breaking a fast moving train.

Mike.

 

Balt's description of what happens after an emergency application is correct but I thought you might like to know the why.  Have you ever ridden a bicycle with hand-operated brakes on both wheels and applied the brakes only on the front wheel?  If so, you probably only did that once because the back wheel (and you) kept moving while the front wheel slowed.

 

Now remember that the order for "Emergency braking needed NOW!" is transmitted from the locomotive(s) to a freight train as a reduction in train line pressure.  I don't know the numbers but trust me, it takes several seconds for that order to reach the rear of the train.  So while the brakes have been applied at the front end of the train, the rear of the train is still trying to move along without the brakes applied.  The result is likely to be as Balt described.  I would disagree with him only in that, IMO, it doesn't take much of a curve, if any at all, for a freight train to derail when an emergency application is made.

 

[BaltACD]

cefinkjr

 

mbinsewi

I had heard on news reports that the engineer saw a displaced rail, and went in emergency breaking.  As I undertsand it, going into emergency breaking will cause a derailment.  Is this true?

Maybe I'm not fully understanding the dynamics of emergency breaking a fast moving train.

Mike. 

Balt's description of what happens after an emergency application is correct but I thought you might like to know the why.  Have you ever ridden a bicycle with hand-operated brakes on both wheels and applied the brakes only on the front wheel?  If so, you probably only did that once because the back wheel (and you) kept moving while the front wheel slowed.

 

Now remember that the order for "Emergency braking needed NOW!" is transmitted from the locomotive(s) to a freight train as a reduction in train line pressure.  I don't know the numbers but trust me, it takes several seconds for that order to reach the rear of the train.  So while the brakes have been applied at the front end of the train, the rear of the train is still trying to move along without the brakes applied.  The result is likely to be as Balt described.  I would disagree with him only in that, IMO, it doesn't take much of a curve, if any at all, for a freight train to derail when an emergency application is made.

Today's trains on Class 1 carriers are, for the most part, required to have what is known as a 'two way EOT'.  The EOT is a radio transmitter/receiver that transmits air pressure and movement data to the locomotive.  The EOT also displays a flashing red light to the rear of the train.  The EOT receives a radio signal from the locomotive when a emergency brake application is detected (initiated either by the engine brake valve or train line).  As such the length of time required for the brake application to be fully propagated is reduced. 

Derailments becuse of emergency brake application are a rare exception, not the rule, no matter the terrain.  Current rules require the crew to inspect the train after every emergency brake application - inspection requirements are modified, but not eliminated, if the air immediately restores after the train stops and the engineer resets the proper controls on the locomotive.

[bartman-tn]

The legal FRA limit for an alinement deviation for the Amtrak speed (60mph - Class 3) is 1-3/4". The NTSB has estimated the alinement deviation at 12"-14". Braking probably had nothing to do with the derailment. The locomotives with their weight probably forced their way through the alinement issue, the baggage car stayed on due to the locomotives, but then the rest of the cars had almost no chance with their higher center of gravity and lighter weights. I've seen this happen before with freight trains where the locomotives get through the sun kink, but the freight cars fail to.