[PRCo] Re: NACHOD SIGNALS--TECHNICAL QUESTION

[Jim Holland]

Good Morning!



> Fred Schneider wrote:

> Nachod signals count cars in a block.  But for the
> real answer, send a letter to PTM addressed to the
> signal guru.  I can see him standing in front of me
> but I'm terrible with names.


	Scott Davis??


	If 2-opposing cars enter the same section, what happens then?   
Doesn't the system go blank?    While the car using the
single-track for a reverse move could  *count--out*  the opposing
car in the single-track, what happens to the  *blank--out*  from
the opposing move?

	.......AND  how far along was the opposing car  --  did both
cars enter the single-track at the same identical time, or was
car  *A*  already beyond the signal when  *B*  made the reverse
move?


>> rogertrolley.1 at juno.com wrote:

>> I just reviewed an old accident (no location) where
>> a single track line had 2 miles between sidings.

>> Car entered single track at location A and a car
>> entered single track at location B at the same time.

>> Car at location B changed ends and returned to
>> dbl track thru signal trippers of NACHOD system.

>> Question is, did he trip signal to green on outbound
>> side, even tho there still was a car in the single
>> track block heading toward location B setting up a
>> potential head-on collision?????  
>> any takers??    cheers rogertrolley


	This is  *theoretically*  possible unless a  *blank--out*  from
opposing movements over-rides cancelling the signal.



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Waiting for a bus is as thrilling as fishing,
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            George Courtauld

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James B. Holland

• Holland  Electric  Railway  Operation....... 
  "O"--Scale St.-Petersburg Trams Company (SPTC)
	Trolleycars and "O"--Scale  Parts
		including Q-Car
	mailto:pghpcc at pacbell.net

• Pennsylvania Trolley Museum
	http://www.pa-trolley.org/
• Pittsburgh  Railways  Company  (PRCo),
	1930  --  1950
• N.M.R.A.  Life member #2190;
	http://www.nmra.org

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