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Origins of Elizabeth s-curve saught


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#21 Guest_SeeBuyFly_*

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Posted 12 April 2013 - 02:50 PM

The track alignment was pretty much destroyed, and they had to take the track out of service until they had a chance to get it all straightened out.

or not...



#22 railiner

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Posted 12 April 2013 - 03:10 PM

Anytime I see or hear mention of the curve at Elizabeth, I can't help thinking back to this day, when tragically some people were killed  by the eastbound Admiral at that location....


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#23 jis

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Posted 12 April 2013 - 04:00 PM

The track alignment was pretty much destroyed, and they had to take the track out of service until they had a chance to get it all straightened out.

or not...

Yeah placed back in alignment would be a more accurate statement. :)



#24 jis

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Posted 11 August 2017 - 11:18 AM

I just noticed that I had grossly underestimated the speeds possible through the Elizabeth curves.
 
In the 2014 ETT before activation of ACSES, the speed limits for the center two tracks (tracks 2 and 3) were respectively 65 (Type A & B First Curve west of MP14) and 55 (Types A and B Curve east of Elmora). In addition due to FRA order and limitations of the ATC system, my understanding is that the ATC system actually forced a code drop to 45mph before entering the curve.
 
In the 2016 ETT after activation of ACSES, the speed limits for the center two tracks (tracks 2 and 3) are respectively  85 (Type A ) and 80 (Type B ) (First Curve west of MP 14) and 75 (Type A ) and 70 (Type B ) (Curve east of Elmora)
 
I had mentioned something like 60/65.
 
The speed limits for the outer tracks (1 and 4) remained 55mph with no change, but with ACSES the code drop to 45 was probably removed. I am not sure. Thirdrail can probably give more upto date info on that.

Edited by jis, 11 August 2017 - 09:19 PM.


#25 Acela150

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Posted 11 August 2017 - 02:16 PM

Jis, the cab signal drop was indeed dropped. If one goes through the curve today it is indeed much quicker then before. This is one area where PTC has actually benefited things.
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#26 Thirdrail7

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Posted 12 August 2017 - 12:08 PM

The speed limits for the outer tracks (1 and 4) remained 55mph with no change, but with ACSES the code drop to 45 was probably removed. I am not sure. Thirdrail can probably give more upto date info on that.

 

 

Jis, the cab signal drop was indeed dropped. If one goes through the curve today it is indeed much quicker then before. This is one area where PTC has actually benefited things.

 

The cab signal codes were not dropped. Even if they were dropped, the actual distant signals approaching the area going west on 1, 2 and 3 track can't display a clear  since it doesn't have a clear aspect.  Neither can the automatic signal on 4 track at the same location. However, the distant signal is capable but you're already down to 45mph. Going east, the distant signals on A and 1 can't display a clear aspect while track 4 and B aren't signaled east. 2&3 track east are capable of displaying clears which is why it isn't likely see the cab drop go away until they change the signal system completely. This is because they want certain locations protected in case there is ACSES failure.

 

There was a plan to change the signals so you could receive a Cab Speed 80. However, since you'd have to physically change the signal bridge, it is unlikely to occur until the convert the territory to 562 (which is slowly occurring.)


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#27 jis

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Posted 12 August 2017 - 01:54 PM

Thirdrail. Thanks for the clarification.

 

So effectively at what speed can the Acelas go through those two curves today? I suppose they can accelerate as fast as possible after meeting the signal restriction on the segment protected by the signal? I guess I am still a bit confused.



#28 Thirdrail7

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Posted 13 August 2017 - 12:38 PM

Thirdrail. Thanks for the clarification.

 

So effectively at what speed can the Acelas go through those two curves today? I suppose they can accelerate as fast as possible after meeting the signal restriction on the segment protected by the signal? I guess I am still a bit confused.

 

You're not confused Jis. You hit the nail on the head. They cab signal drop approaching Elmora is on a timer. An acela will suffer the forced compliance of reducing speed to avoid the penalty. It will knock you down to roughly 60mph going east and 45 mph going west (since the track speed is lower). As soon as it releases you may accelerate and you will hit toe curves at track speed.


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#29 jis

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Posted 13 August 2017 - 04:14 PM

OK I get the gist of it. I am still a bit fuzzy about how the code drop on a timer works. The code drop lasts for a short period starting at what point in time?

#30 Thirdrail7

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Posted 13 August 2017 - 11:49 PM

The timer starts when you pass the signal's impedance bond. You needn't pass another signal or impedance bond for the upgrade. I believe they are set for twelve seconds. At any rate, after the 12 seconds, the cab signal indication will  allow for a greater speed...assuming there is nothing ahead. This is beneficial since it releases regardless of speed.


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#31 jis

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Posted 14 August 2017 - 06:29 AM

Thanks.




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