50 years ago if you were running and you were crossed against traffic, the cab signals would go through all of there indications and then go off line, the engineer would signal with the horn a long and a short and then two longs a short and a long and that indicated to the train crew and anyone else who could hear the signals that the train was now running against traffic and signaling was by the automatic block signals only, the real effect of this was that the locomotive could exceed the posted speed with out the cab signals sounding off a warning in the cab or slowing the unit down. I can tell you that a GG1 could get up and move a lot faster then many people were aware of.
My first (He's since retired) MOP (Manager Operating Practices, AKA road foreman of engines or travelling engineer elsewhere) thought when the UP installed the waysides and CTC that they would petition to remove the ATC. The UP definitely doesn't like (or understand) ATC. Trouble is, it's safer than their own CCS system. What would've been great would be a combination of the 4 aspect cab signal with the speed settings for the individual indications like other systems have.
The cab signal displays the UP uses now have both systems on one box. ATC display on the left, CCS on the right. Even before the merger, UP engines were getting the dual display boxes.
On my preferred assignment (west pool) I get about 40 miles of CCS and 140 miles of ATC.
Jeff
Thank Goodness for electronics in connection with these cab-signal installations! I well remember that when new units would arrive on the railroad, they had to remove the cab-signal equipment from older power to equip the new ones (I was really shocked to see some SD40-2s that no longer had cab signals because of the SD50s and SD60s). Once UP came on the scene, a whole lot more units had the potential to come over our main line, so you needed units that can read both types.I always thought it would be smart for CNW to convert the line to UP's cab signals and retire its archaic system. I guess that's all moot now, with ATCS coming down the road--they can get rid of everything else.
Carl
Railroader Emeritus (practiced railroading for 46 years--and in 2010 I finally got it right!)
CAACSCOCOM--I don't want to behave improperly, so I just won't behave at all. (SM)
Are you saying that the Southern used cab signals in conjunction with ATS? I know that the Southern had ATS on many of its lines: Bristol-Memphis, Chattanooga-New Orleans, Cincinnati-Chattanooga, Salisbury-Morristown, Biltmore-Hayne, (Alexandria?)Monroe-Birmingham, Haleyville-Jasper, Ala., some others--and all of these had ABS. I was unaware that the ATS also used cab signals; indeed, the two times that I rode a Southern passenger engine (in 1969) I did not notice cab signals. Would not the presence of cab signals also have been mentioned in the ETT, as the presence of ABS and ATS was?
Johnny
ATC pretty much works the same as when Carl went out on the road. Only real difference is in the equipment and how it works. Just like everything else, more electronics and computerization of components.
DEGGESTRY: The SOU RR had displays for their ATS I seem to recall. It was in use out of Bristol starting at the Stone lumber co.
Jeff, of course, we know that Carl was relegated to the yard for who knows how long; have there been such changes since he was allowed out on the road?
As to the number of aspects for cab signals, the Southern rule book of about 1940 showed, as I recall, three: clear, approach, and stop. Does anyone know if the Southern ever used cab signals, and , if so, where? Sad to say, I did not find my copy of that rule book when I moved this past March; I hope it did not absolutely disappear during the thirty-eight and a half years that I lived in one place. I did find some treasures that had put themselves into places that were difficult to find.
I considered myself fortunate to have obtained that rule book. Not long after I started to college, the agent who had been in my home town for several years and was patient with me was moved to Forest City, N.C., which was on my hitch-hiking way to and from college. Once when I stopped to see him, he had just received the new rule book, and I asked him if I could have the old one; he was not certain if he had to turn it in, and told me to wait a while. The next time I stopped to see him, he gave the book to me.
For the record, Jeff, it's 100 seconds between buzzers when you're in Restricting, starting any time you release the brake (I had nothing better to do once, and timed it...it was consistent). Of course, that was 40 years ago.
I know that once you have passed a control point and entered a track segment with the traffic set opposite your direction of travel (signal problems, talked by the red,etc.) your not going to get a more favorable (than restricting) aspect until reaching the next control point (interlocking, generally) . Tis indeed dark magic!
blue streak 1 oltmannd [There are a couple of wrinkles. What about the problem of Bi-directional track that is the norm for the PRR NEC ?
oltmannd [There are a couple of wrinkles.
[There are a couple of wrinkles.
What about the problem of Bi-directional track that is the norm for the PRR NEC ?
The details are beyond me on this one. Might involve magic. I might need another night in a Holiday Inn Express.
But, there is some sort of circuitry that knows what the direction of travel is set for when the route is set and the signal is put up at the upstream interlocking. It tumbles down through the blocks, setting all the opposing signals to stop and toggles the block signals to work in that direction.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
rfpjohn Actually the locomotive cab signal displays the condition of the block you are in. There is never a display of the next signal ahead.
Actually the locomotive cab signal displays the condition of the block you are in. There is never a display of the next signal ahead.
Thanks for the correction! (it seems obvious now ....) I am not a C&S engineer, though I did sleep in a Holiday Inn Express once!
The overspeed setting (freight service) for ATC is 73 mph. When you get a restricting cab signal over 40 mph, the high speed setting, you have 6 seconds to get below 40 (not an option unless you're right on the bubble) or go to suppression to avoid the penalty brake application. Get a restricting cab below 40, you have 70 seconds to get below 23 mph, the slow speed setting. Between 22 and 17 mph there is a continuous audible warning, so on a restricting cab top speed (conditions permitting, remember it is Restricted speed and that rule applies) is 17 mph. About every 90 seconds when on a restricting cab, the ATC needs to be acknowledged, like an alerter.
The UP also has 4 aspect coded cab signals on the original UP side, but there is no overspeed setting for the indications. You only need to acknowledge the aspect change, there's nothing that forces you (other than following the rules) to actually slow down to the corresponding indication.
Wow! Two aspect, clear and restricting? Must be a nightmare for train handling! We have four aspects, clear with freight overspeed set at 60.4mph on the newer power, approach-medium/limited set at 45mph, approach set at 25mph and restricting, which also will allow 25 though the rule limits you to a maximum of 15 (and you had better be prepared to stop within one-half your range of vision). Is there an overspeed setting on the former C&NW territory, or do you simply acknowledge the downgrade and use your best judgment?
rfpjohn Actually the locomotive cab signal displays the condition of the block you are in.
Actually the locomotive cab signal displays the condition of the block you are in.
That is the best way to put it. Cab signals display the condition of the block you are in, wayside signals display the condition of the block you are about to enter.
Before the UP added wayside signals to the former CNW's ATC, there was no formal marking of block boundaries at most of those locations. There were insulated joints and a relay house. As you became familiar with the territory, you started to know where they were and an idea of where a preceding train was when you got train control. The ATC is a two aspect, clear or restricting form of cab signal.
Now that UP has added wayside signals to the ATC territory, you can get a restricting cab signal at a wayside displaying an advance approach.
Thanks for the replies, all!
Don, your explanation was perfect. Thanks for taking the time to write that all out -- that was exactly what I needed for my understanding to click into place.
Two more questions:
blue streak 1 What about the problem of Bi-directional track that is the norm for the PRR NEC ?
To add to that, how does it work when a train is switching within a block?
On lines without fixed wayside signals (NORAC 562 or equivalent), how are the block divisions marked?
Actually the locomotive cab signal displays the condition of the block you are in. There is never a display of the next signal ahead. As you mentioned, Conrail practice (and maybe PRR?) was to install a "cut section" which would drop the cab signal to restricting part way through the block, approaching a stop indication. CSX has adopted this practice on the RF&P sub at some, but not all home signals. All signal modifications seem to be randomly applied, which is very frustrating when operating over the territory!
TrainManTy Howdy all, Railroad signaling is one of my favorite aspects of railroading, but I'm having trouble understanding how cab signals operate. For those who don't know (but want to follow along), these are indications in the locomotive cab that augment or replace fixed wayside signals. My question relates to typical US pulse-code signals, developed by the PRR and now the de facto standard in the country. Several of my local railroad lines use NORAC Rule 562, with wayside signals at interlockings only -- all intermediate automatics are cab-only. I understand that this style of cab signal is continuous and signals can upgrade or downgrade at any time...but how do signal blocks work between interlockings? Are there specific blocks that are controlled by cab signals, exactly like a standard signal installation, but without the physical waysides? How are they marked? I consider myself very signal-savvy, I'm just having trouble wrapping my head around this one. Any insight would be appreciated! Thanks!
Howdy all,
Railroad signaling is one of my favorite aspects of railroading, but I'm having trouble understanding how cab signals operate. For those who don't know (but want to follow along), these are indications in the locomotive cab that augment or replace fixed wayside signals.
My question relates to typical US pulse-code signals, developed by the PRR and now the de facto standard in the country. Several of my local railroad lines use NORAC Rule 562, with wayside signals at interlockings only -- all intermediate automatics are cab-only.
I understand that this style of cab signal is continuous and signals can upgrade or downgrade at any time...but how do signal blocks work between interlockings? Are there specific blocks that are controlled by cab signals, exactly like a standard signal installation, but without the physical waysides? How are they marked?
I consider myself very signal-savvy, I'm just having trouble wrapping my head around this one. Any insight would be appreciated! Thanks!
The blocks are the same, insulated joints and all.
The heart of it is the coded track circuit - that essentially replaces the wayside pole line and DC track circuit. Here's how:
I am at a signal that's at stop (lets say, there is a train in the block ahead).
Because the signal's at stop, It feeds "approach" code into the track (75 beats per minute). That code reaches the next signal up the line.
It sees 75 beats a minute, so it sends "approach medium" (120 beats per minute) into the track to toward the next signal up the line.
That next signal sees the 120 code and send "clear" (180 beats) up the line...
The codes are sent on carrier frequency. PRR used 100Hz for this.
The locomotives have antenna (receiver bars) ahead of the front axle that are tuned to listen for this 100Hz carrier. When they pick it up, the "beats" are translated by some tuned relays in the cab signal box that pick up when they are tickled just right.
So, the locomotives will always display what the next signal ahead displays.
The train shunts the coded track circuit the same way it does a DC track circuit. Under and behind the train there is no code or carrier at all.
If the train ahead clears the block it's in, then each subsequent block "improves" one aspect and the cab display "improves" as well.
There are a couple of wrinkles. Often, the coded track circuit's can't reach the whole block length, so they cut the block in two and put in a "repeater". This is known as a "cut section".
Modern cab signal systems on locomotives (and wayside) are all solid state/microprocessor based. The tuned relays are long gone...
There is often a small "cut section" just before an interlocking that gives the aspect of the signal just ahead. For example, at Chase MD, the Conrail locomotives would have gotten a restricting in the cab something like 1000 feet ahead of the home signal prior to sliding through the home signal at stop.
Amtrak's ACSES system is still basically the PRR cab signal system except they have layered on a second carrier frequency to convey even more signal aspects.
Does the Lion ever go to the zoo to see if there is a new gnu at the zoo? If he did might not have to worry about a wildebeest for a while.
There are many different ways of doing this, and I do not know all of the details.
LIRR used the PRR system, Metro North uses a different system, I do not know what AMTK or NJT uses, but when running on MNCR tracks, AMTK needs to use the Metro North system, when running in New Jersey it likely uses the old PRR system, unless that has been replaced. LION does not know. LIONS worry about wildebeests, let others worry about interlocking.
But like ewe, LION likes signals and interlockings. This is what him built for his own railroad...
The Route of the Broadway Lion The Largest Subway Layout in North Dakota.
Here there be cats. LIONS with CAMERAS
In the pre-CSX days on the RF&P, we had non-wayside blocks between interlockings if we ran the lefthand main. (3 track north or 2 south). The exception being the intermediate immediately preceding each interlocking. Block limits were designated by number plates on the backside of the intermediates faced for normal, righthand operation. So, yes, there were specific blocks, as in wayside. I'm pretty sure other carriers systems were set up the same way.
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