Contradiction remains

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Posted by 243129 on Wednesday, October 23, 2019 10:59 AM

charlie hebdo

Your comments on the current discussion about the horns would be helpful. 

 

Were I the engineer on Train 175 I would have used a succession of short sounds on the horn to indicate impending disaster and I would have applied the emergency brake far sooner than Ms. Reese did.

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Posted by Overmod on Wednesday, October 23, 2019 12:41 PM

Something that has been 'added' since the beatings stopped is the datum that the conductors were said to be walking in the gauge, and moved to the tie ends when hearing and seeing 66.  Properly-conducted testimony would have revealed this as part of the interviews for "the NTSB record" more directly, and perhaps it could have been asked of Sahara either directly or as a 'callback'.

It does change the picture of what to do ... slightly ... if she saw them move over and thought they were about to go further.  Still doesn't change putting it in emergency some time ... even a few milliseconds ... before the actual impact.

As noted, we need an emergency code, to be learned by heart along with the other horn signals, for "emergency look around you" rather than just "emergency".  That would consist of enough 'dead time' between signals to allow any echoes to die to the point other horns sounding emergency could be heard and distinguished.

Such is my non-operator's opinion, as learned in part from wiser people with running experience.

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Posted by Euclid on Wednesday, October 23, 2019 3:11 PM

Overmod

As noted, we need an emergency code, to be learned by heart along with the other horn signals, for "emergency look around you" rather than just "emergency".  That would consist of enough 'dead time' between signals to allow any echoes to die to the point other horns sounding emergency could be heard and distinguished.

Such is my non-operator's opinion, as learned in part from wiser people with running experience.

 

We already have that emergency whistle signal.  It is exactly as what Joe said he would have done.  This is part of every reference to train whistle/horn signals, going way back in history.  I assume it was chosen precisely for the reasons you suggest.  Leave some gaps of no tone for a better chance of hearing a tone from another whistle.  The gaps also tend to give a punch feeling of urgency which is a fundamental part of emergencies.  Note that it is exactly opposite of the "laying on the horn" described by the engineer of 175, and was possibly also done by the engineer of 66.  That signal readily makes two horns sound like one.

Along with making a punchy horn signal, an engineer should watch for clues that a person in harms way may not realize that fact.  This should have been apparent to the engineer of 175.  From her viewpoint, the action of the two victims either meant they were not aware of 175 because they were distracted by 66, or they were playing chicken.  Then one would need to ask themselves how often do men in green safety vests play chicken?

Particularly the fact that the two men moved away from the path of 66, but remained in the path of 175, should have made it clear that they were unware of 175 despite the laying on of the horn.  They were unaware of 175 because they thought they were hearing only the horn of 66. 

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Posted by Overmod on Wednesday, October 23, 2019 4:37 PM

Euclid
We already have that emergency whistle signal.  It is exactly as what Joe said he would have done.  This is part of every reference to train whistle/horn signals, going way back in history.

But the 'new thing' that we have to consider adding is the effect of directional echo on the emergency signal.  For that, we need longer, or differently-spaced, gaps of silence between the 'blasts' -- and to me, this means that the shorter blast clusters need to be decided as something unambiguously meaning not just "proximity danger" but "look around you danger".

This might be as simple as the MTA's long-short repeated three times ... then delayed for a second, the whole thing being sent with as distinctive a 'hand' on the button as possible.  Just as wireless telegraphers could recognize two signals as different, this optimizes the different ways a human ear in a multipath reflection field might discriminate two signals essentially trying to send the same priority message in the same few seconds.  

I would note that a considerable amount of work on high-criticality alerts was done in ITU R10 and other working groups.  One example was the stall alert in heavy aircraft, which instead of blaring in your ear calls your attention (calmly, to non-pilots, considering the importance!) speech-synthesizing something directed toward relieving the dangerous condition, or alerting to do something (pull up) or what's becoming a potential problem (terrain).  It would be delightful if we could provide a PA function via some terrifying auxetophone that would allow voice alerts at substantial distance ... but I'd certainly settle in the short run for unambiguous alerting.

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Posted by Euclid on Saturday, November 16, 2019 8:45 AM

Overmod
 
Euclid
We already have that emergency whistle signal.  It is exactly as what Joe said he would have done.  This is part of every reference to train whistle/horn signals, going way back in history.

 

But the 'new thing' that we have to consider adding is the effect of directional echo on the emergency signal.  For that, we need longer, or differently-spaced, gaps of silence between the 'blasts' -- and to me, this means that the shorter blast clusters need to be decided as something unambiguously meaning not just "proximity danger" but "look around you danger".

This might be as simple as the MTA's long-short repeated three times ... then delayed for a second, the whole thing being sent with as distinctive a 'hand' on the button as possible.  Just as wireless telegraphers could recognize two signals as different, this optimizes the different ways a human ear in a multipath reflection field might discriminate two signals essentially trying to send the same priority message in the same few seconds.  

I would note that a considerable amount of work on high-criticality alerts was done in ITU R10 and other working groups.  One example was the stall alert in heavy aircraft, which instead of blaring in your ear calls your attention (calmly, to non-pilots, considering the importance!) speech-synthesizing something directed toward relieving the dangerous condition, or alerting to do something (pull up) or what's becoming a potential problem (terrain).  It would be delightful if we could provide a PA function via some terrifying auxetophone that would allow voice alerts at substantial distance ... but I'd certainly settle in the short run for unambiguous alerting.

 

Just blowing the proper signal in this case would have had a good chance of preventing the two deaths.

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