jake9wi
Member
Hi all. I'm fresh to rail monitoring and have noticed in the database that some channels say road and some dispatch. What is the difference between these?
Road vs Dispatch
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Some railroads use two different channels for communication between the dispatcher and crews, most use just one.
Think of the Road channel as what everything on a given stretch of track monitors as a hailing freq, kinda like Marine Ch-13 on a river. You might have maintenance crews using other freqs for their own ops trackside, or porters using other freqs for activities in sleeper or diner cars, but anyone who wants to speak with the engineer or conductor will be doing it on the Road channel. Even if Dispatch has its own frequency, it'll most likely still use the road channel to actually hail the train. Once contact is established they may talk on either the road or dispatch channel, depending on their policies or whims.
Dispatch involves control of the rail lines and giving individual trains the authority to use those lines--often involving some kind of network where the radio signal is relayed to a remote location. (like CSX in Jacksonville, FL or NS in Atlanta, GA) If Dispatch has its own frequency (or pair), the train engineer will likely use that frequency to hail the dispatcher and conduct the necessary business. But if Dispatch needs to hail the train, I believe it'll do so on the Road channel.
Also note that there may be a Yard channel, which would function as the road channel within yard limits, or at least on yard tracks. Road channel might still be used in a yard, particularly if a train is just passing through.
73/Allen (N4JRI)
Dispatch involves control of the rail lines and giving individual trains the authority to use those lines--often involving some kind of network where the radio signal is relayed to a remote location. (like CSX in Jacksonville, FL or NS in Atlanta, GA) If Dispatch has its own frequency (or pair), the train engineer will likely use that frequency to hail the dispatcher and conduct the necessary business. But if Dispatch needs to hail the train, I believe it'll do so on the Road channel.
Also note that there may be a Yard channel, which would function as the road channel within yard limits, or at least on yard tracks. Road channel might still be used in a yard, particularly if a train is just passing through.
73/Allen (N4JRI)
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The road/dispatch thing is primarly an east coast thing, specifically CSX and former CSX railroads.
"Back in the day", the dispatchers had essentially open radios - so they heard everything that was going on. However "back in the day" many things were still handled by hand signals, trainorders and other non-radio dependent methods of operation. As tower and control operators were eliminated and more responsibility fell onto the dispatchers - along with advances in CAD and radio technology, the workload and radio use increased. With the older radio setups, some railroads took the dispatchers off the "road" channel and put them on their own "dispatcher channel".
Depending on the railroad's operating practices, the dispatcher could turn on the "road channel" and ask for a crew to come to the dispatcher channel for further authority, updates or whatnot. Conversely, the road crew could change to the dispatcher channel and do the same.
In other cases, some railroads would go with the duplex setup whereas the crews and dispatcher used a "split" channel setup to talk to the dispatcher - Dispatcher transmits on channel A, train receives on channel A. Train transmits on channel B and dispatcher receives on channel B. This reduced some of the chatter than other trains would receive, similar to how some taxi company's were setup so that rival cabs couldn't steal fares, but reduced what the drivers heard on the radio.
Most railroads now use a single channel (west of Chicago we shall say). The dispatcher radios at the office are normally muted, and if a crew needs to talk to the dispatcher, they use a DTMF code which will alert the dispatcher that someone wants to talk to them. The larger railroads typically use a Avtech console with receiver voting. It will show on the console which tower heard the best signal from the train so the dispatcher can select the best tower to talk on.
Some smaller railroads may use PBX systems, and other small ones or regionals have been known to use LTR or DMR systems for their needs.
So after all that text, if you want to monitor railroads with such "split" channels, you need to scan both.
"Back in the day", the dispatchers had essentially open radios - so they heard everything that was going on. However "back in the day" many things were still handled by hand signals, trainorders and other non-radio dependent methods of operation. As tower and control operators were eliminated and more responsibility fell onto the dispatchers - along with advances in CAD and radio technology, the workload and radio use increased. With the older radio setups, some railroads took the dispatchers off the "road" channel and put them on their own "dispatcher channel".
Depending on the railroad's operating practices, the dispatcher could turn on the "road channel" and ask for a crew to come to the dispatcher channel for further authority, updates or whatnot. Conversely, the road crew could change to the dispatcher channel and do the same.
In other cases, some railroads would go with the duplex setup whereas the crews and dispatcher used a "split" channel setup to talk to the dispatcher - Dispatcher transmits on channel A, train receives on channel A. Train transmits on channel B and dispatcher receives on channel B. This reduced some of the chatter than other trains would receive, similar to how some taxi company's were setup so that rival cabs couldn't steal fares, but reduced what the drivers heard on the radio.
Most railroads now use a single channel (west of Chicago we shall say). The dispatcher radios at the office are normally muted, and if a crew needs to talk to the dispatcher, they use a DTMF code which will alert the dispatcher that someone wants to talk to them. The larger railroads typically use a Avtech console with receiver voting. It will show on the console which tower heard the best signal from the train so the dispatcher can select the best tower to talk on.
Some smaller railroads may use PBX systems, and other small ones or regionals have been known to use LTR or DMR systems for their needs.
So after all that text, if you want to monitor railroads with such "split" channels, you need to scan both.
Don't forget that in many former Southern territories, a half-duplex mode was used where the trains talked on one frequency and the dispatchers talked on a different frequency. I think NS has moved away from that, though.
They're slowly in the process; half-duplex is being removed as they convert the base stations. I heard from someone on the CNO&TP that increased radio traffic was causing issues in that trains and track workers couldn't hear what other trains and track workers were saying on the DS channel.
Two-channel operation for NS is part of the consolidation of dispatcher desks after moving everybody to Atlanta. Supposedly each DS desk will have a dedicated road channel and a dedicated dispatcher channel.
The Columbus District through here has the Kenova desk up to Rickenbacker and the Sandusky desk from Rickenbacker to Columbus; both are sharing 161.190 along with the PTC desk and road traffic and TSAs, and it's stupidly busy on the radio.
The Kenova District from Portsmouth east has been on 161.250 for years and isn't really having any major radio issues. I'm a but surprised they haven't already changed the Columbus District for the Kenova desk, as there are only three base stations to deal with: Ringgold, Summit Hill and Portsmouth. They could change the Columbus District to 161.250 with relative ease.
N9DCW
Member
I've just began listening to my local road/ dispatychannel 160.455 for UNION PACIFIC here in Provo UTAH so I'm a rookie! Can anyone tell me what the 3 digit DTMF tone I hear locomotive engineers punch in on the Mic/radio key pad? It's then followed by a loud single tone burst that comes back sometimes with a strong signal and some with weaker signals. What are the 3 digit DTMF numbers being dialed and are they uniform for like remote commands
That's how units in the field call the dispatcher. The dispatcher doesn't monitor the radio continuously as there's just too much chatter, so the radios are normally muted at the dispatcher's location. When a unit in the field punches in the DTMF code for where they are, it pops up a notification on the dispatcher's panel. The dispatcher then selects that base station and responds to whoever called.
N9DCW
Member
THANK YOU!!
Don't know what specific 3 numbers are used.
The reason the response tone is sometimes strong and sometimes weak is because you are likely picking up different towers. I can get at least 3 different towers with full quieting at my location and towers father out as well but they come in weaker.
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Most larger railroads use the AVTEC system which also has a voter comparator option (UP and I think CSX does).
when the dispatcher needs to be called, this allows for that dispatcher DTMF sequence to used, instead of using tower specific tones (prior to using voters).
99 % of the time the tower with the best reception of the radio calling will be selected and the confirmation tone will be transmitted by that tower.
Sometimes the system goofs and multiple towers will be chosen, but not usually (and sometimes two people are “toning” up the dispatcher and it hears both and answers both.
BNSF in many areas still uses manually selected towers but is also setup where you can call the dispatcher, police, help desk etc - but requires employees to know what site is in range.
On the AVTEC consoles, when a call is processed it will show which tower a call was received on and when the dispatcher is ready to answer, they simply select and unmute that tower.
Depending on what is going on, they have the option to listen to one or multiple towers or keep them muted
when the dispatcher needs to be called, this allows for that dispatcher DTMF sequence to used, instead of using tower specific tones (prior to using voters).
99 % of the time the tower with the best reception of the radio calling will be selected and the confirmation tone will be transmitted by that tower.
Sometimes the system goofs and multiple towers will be chosen, but not usually (and sometimes two people are “toning” up the dispatcher and it hears both and answers both.
BNSF in many areas still uses manually selected towers but is also setup where you can call the dispatcher, police, help desk etc - but requires employees to know what site is in range.
On the AVTEC consoles, when a call is processed it will show which tower a call was received on and when the dispatcher is ready to answer, they simply select and unmute that tower.
Depending on what is going on, they have the option to listen to one or multiple towers or keep them muted
CSX does, and NS uses AVTEC or something like it as well; they've had a single-call (each dispatcher desk has a unique DTMF code) capability for about 20 years. Conrail was the last one around here still using a unique code for each radio base station, even at the end in 1999.
I hear this from CSX but never from NS, at least around here. Two CSX towers will answer back with their peculiar "brrrrrp" tone, usually when the calling unit is equidistant and within line of sight between two towers.
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They are using an older version of what’s out there, but of course it’s highly configurable.
AVTEC was bought out by Motorola a few months back so I’m sure some changes will eventually be pushed.
AVTEC,which has public safety customers has/had a deep industrial base so this will become interesting.
AVTEC was bought out by Motorola a few months back so I’m sure some changes will eventually be pushed.
AVTEC,which has public safety customers has/had a deep industrial base so this will become interesting.
Groeteschele
Member
More information to help learn of more railroad radio operation.
www.trainaficionado.com/why-should-every-railfan-have-a-scanner/
milf
Careful, I CAN hear you!
Sometimes on CSXT here in Indy, you will hear the Dispatcher down in Jacksonville, tell the train "Hold on a second, I am going to switch towers, this one is really not cutting it."... So sometimes the "voter" is not quite getting the right "choice" which could be due to multiple factors, but when it happens, the dispatcher then has to play "musical buttons" so to speak to find the real tower that has the best signal for both ends. And as to the Motorola buy out and so forth... How's that gonna work when in a not too very far off future, NXDN DOES become the main format in use? I see lots more expense now since Motorola does not have NXDN gear do they?
Nope. Motorola does not sell or support NXDN gear; directly competes with their TRBO offerings. They'll have to keep at least a minimal amount of support for NXDN in AVTEC equipment, but knowing Motorola, it will be as minimal as they can get away with.
Somebody mentioned to me the other day it's pretty ironic that Motorola abandoned the railroad market when they discontinued their locomotive radios, yet here they are jumping back in again.
Update: According to the AVTEC web page, 70% of US Class I railroads use the Scout dispatch console (including NS). There's only nine, so two of them are odd man out. There's also 25 shortline and transit systems using it; might be interesting to know who (I'm guessing G&W and WATCO, and that RJC is a possibility).
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