Why split AAR Channels?

[Nasby]

I am curious as to why railroads sometimes split the receive and transmit AAR radio channels.

For example, contact the yardmaster on: Receive AAR 46 Transmit AAR 08

Is it for a repeater input?

 

[ecps92]

Some systems - Yes it might be a Repeater

Other systems - No it's a duplex system.
why ? The Conductor should only be listening/paying-attention to Dispatch

I am curious as to why railroads sometimes split the receive and transmit AAR radio channels.

For example, contact the yardmaster on: Receive AAR 46 Transmit AAR 08

Is it for a repeater input?

 

[radioman2001]

NYCTA did that back in the 80's (don't know if still true) to ensure the engineer was listening to a dispatcher and not blocked by a local train radio transmitting. I do know the engineers were not happy when we first started putting in the new radios. They tried to break them by slamming the radio against L pillars while carrying them to the train each day.

 

[timkilbride]

I have never used a split channel configuration, but it wouldn't help my situational awareness only being able to hear one side.

Tim.

 

[RadioDitch]

Here in the Northeast, CSX is notorious for using repeaters in the yard to prevent any issues of the headend receiving the conductor/brake/utility's portables. Generally, they work it where the ground-man is transmitting into the repeater, and listening on the output...and the head-end just transmits simplex on the output. This is the case in places like Selkirk, North Croton, Baltimore (maybe not any more), and Cumberland.

You also have railroads with very challenging terrain that can inhibit efficient communications via simplex/remote base operation as is standard, and aren't equipped with microwave or fiberoptic links to tie bases together. Ones that come to mind using repeaters at the moment are the NYS&W Northern Division, New England Central, and Vermont Railway System.

In a duplex system it generally works like this. You have your transmit channel, and your receive channel. *Generally* your transmit channel would be the road channel, and your receive channel would be the dispatcher's line to you. This allows the dispatcher to hear everything, but the dispatcher to speak to you interrupted or at a higher power that would completely step on other operations. When you're not speaking to the dispatcher, you would have the road channel as your TX & RX and operate normally, until the dispatcher requested you to call or you called him.

 

[kb2vxa]

These are the old PBX radio telephone channels, full duplex because they're the radio end of a Private Branch eXchange telephone system. That's why on railroads still using them the cab radio has a telephone type handset, however they have mostly been supplanted by cell phones particularly in yard operations.

 

[K4DHR]

NS does it for dispatcher communications, when you hear the dispatcher say , "go to channel 2", they use a separate transmit and receive frequency. I assume this is done to keep communications (such as when copying track warrants) from being stepped on by other transmissions.

Road channel is still simplex.

 

[kb2vxa]

Sort of, putting the dispatcher on a channel separate from the road/yard his/her transmissions don't get stepped on by road/yard traffic and unrelated road/yard traffic doesn't get stepped on by the more powerful base. Also, being a full duplex extension of the telephone system the dispatcher can hear the train even while he/she's talking although the train can't, being semi-duplex. In other words the train can interrupt the dispatcher (making a long transmission) but the dispatcher can't interrupt the train making short acknowledgements. CSX has a PBX in Lakewood, NJ but I never hear any traffic on it or the road because with so little industry down here these days one short train a week doesn't warrant it.

 

[RadioDitch]

...however they have mostly been supplanted by cell phones particularly in yard operations.

That would be incorrect. Per FRA Emergency Order 26, it is illegal for a member of T&E to use any wireless communications device, other than railroad radio, while operating their train. NS went even further and adopted the policy that cell phones cannot even be powered on while T&E is in service on the property. This order and all also applies to MOW personnel in the field on-board equipment, as well as anyone from any department operating high-rail or rail-bound technical equipment.

Reason nothing is heard on the CSX PBX in Lakewood is because the hardware is no longer at that location. Southern Secondary trains also make little chatter on the road channel because there is no opposing traffic when the SA job works down there, and they get their Form D over landline at Browns Yard before they even go outside usually.

 

[radioman2001]

I don't think that's quite right, the way I read it is that if the cellphone is being used for rail operations or MOW,MOV,and MOE that's OK, but for any other purpose that's a no no, that's at least the way it is at MNRR. MOW on the Conn side uses nothing but cellphones, so much so that their channel has been loaned to the MTA PD at times due to it's non use.

 

[RadioDitch]

I don't think that's quite right, the way I read it is that if the cellphone is being used for rail operations or MOW,MOV,and MOE that's OK, but for any other purpose that's a no no, that's at least the way it is at MNRR. MOW on the Conn side uses nothing but cellphones, so much so that their channel has been loaned to the MTA PD at times due to it's non use.

You guys on MN are in your own world. lol. That is how the order was intended, and that's how NS, CSX, and CRCX (Conrail Shared Assets) interpret it.

 

[kb2vxa]

"Per FRA Emergency Order 26, it is illegal for a member of T&E to use any wireless communications device, other than railroad radio, while operating their train."

I didn't say anything about operating a train, yard operations are another story. I'm familiar with the order and why it's an emergency, pick one:
Train crash probe focuses on cell phones - US news - Life | NBC News
Commuter train engineer didn't hit brakes - US news - Life | NBC News
Engineer in Deadly LA Train Crash Was Texting - Washington Post Investigations
California train wreck caused when engineer failed to stop, say officials - New York Daily News

That's not to say how any individual railroad writes its operating rules, only what the FRA Order says. You guys are talking about eastern railroads, unless I'm mistaken it wasn't long ago BNSF started using Nextel for yard ops and there could be others, worth looking into if it really matters to you.

"Reason nothing is heard on the CSX PBX in Lakewood is because the hardware is no longer at that location."
That's as good a reason as any, frankly I had no idea the track was used by anything but that once a week out of Browns. Yeah, that Form D sounds about right, there are no signals down here south of NJT where they branch off at Red Bank. BTW back in the good old days the CNJ operated passenger traffic over that route, today it's technically Conrail (CSX/NS Shared Assets). Those are the legendary Budd RDC-1s in Lakewood

 

[Jimru]

Hey guys,

If it means anything, I regularly monitor the MTA subways and I hear traffic both to and from dispatch as well as the trains on one of three frequencies.

There seems to be a lot of traffic getting stepped on, quite often. I don't know enough about the system go know if what I am hearing is the same as what the dispatch and train operators are hearing, but it sounds like some confusion is going on because of this.

 

[kb2vxa]

NYCTA has several high power repeaters I can hear like gang busters down here. You're hearing what everybody hears, with all that mish mash the dispatcher isn't the only one confused and annoyed. It all comes down to lack of proper training (pardon the pun) when they think it's a telephone and talk all over each other.

 

[Jimru]

NYCTA has several high power repeaters I can hear like gang busters down here. You're hearing what everybody hears, with all that mish mash the dispatcher isn't the only one confused and annoyed. It all comes down to lack of proper training (pardon the pun) when they think it's a telephone and talk all over each other.

Thanks, Warren.

It's hard for me to believe that there aren't more accidents with all of the crosstalk, sometimes!

I monitor the train/dispatch channels, using earphones, every time I use the subway. Actually, even with all of the craziness, I feel like I have a very good idea of what is going on when I travel and on a number of occasions over the years, the monitoring has allowed me to really be a step ahead of the average commuters.

I don't bother monitoring the Transit cops, unless I hear something on the dispatch/train channels that mentions police activity.

Same thing with Amtrak, although on long rides, if there is a crying baby, or a loudmouth on a cellphone, the earphones get plugged into the iPhone and I blast some rock 'n roll!

Regards,
Jim

 

[kb2vxa]

At least the track side signals and train protection systems don't get confused. Oh what is that? There's a little pop up arm at every signal that raises or a magnetic system that when the signal goes red trips the emergency brake so had the dispatcher turned the signals red The Taking Of Pelham 1-2-3 would never have happened. Ah, who in Hollywood ever heard of a reality check? (;->)

Oh, loud sounds can permanently damage hearing and loud music in earphones is the worst. Keep it down and don't think I'm just being a crusty old fart, I speak from experience. AAY? What say sonny?

Hello,
Is there anybody in there?
Just nod if you can hear me
Is there anyone home?

...You are only coming through in waves
Your lips move
But I can't hear what you're saying

Yeah, not deaf yet but getting there.

 

[Jimru]

At least the track side signals and train protection systems don't get confused. Oh what is that? There's a little pop up arm at every signal that raises or a magnetic system that when the signal goes red trips the emergency brake so had the dispatcher turned the signals red The Taking Of Pelham 1-2-3 would never have happened. Ah, who in Hollywood ever heard of a reality check? (;->)

Oh, loud sounds can permanently damage hearing and loud music in earphones is the worst. Keep it down and don't think I'm just being a crusty old fart, I speak from experience. AAY? What say sonny?

Hello,
Is there anybody in there?
Just nod if you can hear me
Is there anyone home?

...You are only coming through in waves
Your lips move
But I can't hear what you're saying

Yeah, not deaf yet but getting there.

I can't hear you, I have two scanners in my ears!

 

[burner50]

At least the track side signals and train protection systems don't get confused. Oh what is that? There's a little pop up arm at every signal that raises or a magnetic system that when the signal goes red trips the emergency brake so had the dispatcher turned the signals red The Taking Of Pelham 1-2-3 would never have happened.

Sounds like total nonsense to me... You must get your technical info from the same place as the people who made the movie 'unstoppable'.

 

[KD6RRR]

Actually Burner, you are both correct. Such a mechanical auto stop system would be a disaster, not to mention an operating nightmare, on a modern day freight railroad.

However, the "pop up bar" stop system he is referring to has been used for a long time on the New York City subway system, and maybe even others. Here is a link describing its operation-

http://www.nycsubway.org/wiki/Subway_Signals:_Train_Stops

 

[Jimru]

Actually Burner, you are both correct. Such a mechanical auto stop system would be a disaster, not to mention an operating nightmare, on a modern day freight railroad.

However, the "pop up bar" stop system he is referring to has been used for a long time on the New York City subway system, and maybe even others. Here is a link describing its operation-

http://www.nycsubway.org/wiki/Subway_Signals:_Train_Stops

There have been some crashes in the NYC subway system over the years that make me wonder how well that system works. It may be that it was operator error, and the lights were green, so that the auto stop would not have been activated.