union pacific cab codes

[Anonymous]

Can anyone advise me of what kind of cab code sysytem the UPRR uses? On the northeast corridor, we code 100Hz AC energy onto the rails (and 250Hz in some limited locations). We are presently using the 75, 120, and 180 pulses per minute rates. I had read some railroads have used 60Hz, but, would have to use 100Hz in areas where interference was caused by a power company's high voltage transmission lines. I had also heard that the Sante Fe had also used a cab code system, but, I'm not sure if they still do. Any info would be greatly appreciated! Please e-mail directly, if you wish (in case of a lengthly reply - which still would be greatly aprreciated!) [:)]

[Anonymous]

I am also interested in knowing the breakdown of CCS signals.
Will someone in the know please enlighten us.

[Anonymous]

I can answer about Amtrak's cab code system, and, this may apply to most other railroads. Coded AC voltage pulses are placed onto the rails. Located under the engine, or, the controlling cab, of the train are pick up coils that are placed ahead of the front wheels and about 8 inches or so above the rails. The electrical pulses on the rails are coupled to the train's pickup coils in the same manner a transformer works. The pulses are decoded by the on-board cab code system to display the proper cab code signal inside of the operating cab of the train. For a clear signal, we place 100Hz of AC energy onto a set of contacts in a relay. The coil of the relay will be controlled by pulses of 12 or so volts DC. The contacts inside of the relay are then moving at the same rate as the DC coded pulses that are placed on the relay's coil. The internal contacts of the relay are then making/breaking the 100Hz AC energy at the coil's applied code rate and then the "pulsed" 100Hz AC is coupled to the rails via a transformer. For a clear straight move, we would send out 180 code, or, 180 beats per minute, of coded AC onto the rails. For a crossover move (approach medium), 120 code would be transmitted onto the rails. For an approach signal, 75 code would be transmitted. A Restricting cab signal occurs when there isn't any code on the rails (or, an out of spec. code is detected). This is just a basic explanation, and, since I am new on here, I don't know how many words a reply post can have. Please feel free to e-mail me for any other questions. I am still searching for cab code signal info on the UPRR and Sante Fe.

[Anonymous]

Amtrak-tom,
Great info. So each signal aspect has a frequency that coresponds to it. That makes perfect sense. I would imagine that the freqs are the same with other roads. If not please let us know. Thanks for the explaination.

[Anonymous]

Dear Wisser,

I had read once that 60Hz was used as a code AC frequency for the rails, except, in areas where a power company's transmission lines would cause interfernce. Then, 100Hz would be used. I understand way up north, our 25Hz traction currents to power our electrifieds would cause interference, so, they used 91 and two thirds Hz (or, something strange like that). 100Hz was chosed for the PRR's signal system power so that the 25Hz wouldn't influence it and cause things like false clear signals, etc. But, in some places, the 25Hz did interfere with the 100Hz, so, they tried an odd AC freq. like 91 2/3Hz. This has to do with harmonics (i.e. 25Hz, 50Hz, 100Hz). I was once told that the UPRR used a coded DC cab signal system. I didn't think that was true, because of the high losses of DC over distances. Tom Edison was a supporter of DC energy, but, George Westinghouse won with his push for AC energy (though the AC generator was invented by Tesla, but, George had the $$$ while Tesla, though being a genius, was earning $2 per day digging sewers!). <---- Got that from the History Channel the other night! Anyways, back to the UPRR and Sante Fe, I'm still waiting to hear from someone who knows just exactly those 2 railroads were using!

[Anonymous]

Dera Wiser,

There are also 270 and 420 code rates used (beats per minute). Amtrak plans to use the 270 code in the near future when we move from the 4 aspect cab signal system to the 9 aspect cab signal. Then, we will be placing 100Hz and 250Hz coded AC pulses on the rails. We use a 50 code rate for keeping relays in motion inside of interlockings because it was found we couldn't take a relay from a dead stop to 180 code quick enough when a train entered the interlocking. This was causing "cab flips" where a cab signal was displaying a "clear" but then dropped down to "restricting" then back up to "clear" again. Keeping a relay in motion at 50 code would allow it to jump to 180 code without the on-board cab signaling system seeing this (no more "cab flips").

[Anonymous]

Thank God I was a machinist. That was about as clear as mud. I just kept the prime movers running.

[Anonymous]

Marty,

I just read your profile, you worked for the UPRR? Can you answer my question posts about the cab signals used on the UPRR??

[Anonymous]

I am returning to the "hobby" of railroading after an abscence of about 15 years, and over the last year the gear head in me has been pulling me more and more to studying technical aspects of real trains.

I did not know such a system exists. I'm guessing that basically with this system you can read a signal long before visual contact.

With today's technology, why not have a "repeater" of the dispatcher's board in the locomotive's cab showing the status of all track ahead of the train.

[Anonymous]

Amtrak-tom,
It sounds to me like my previous assumption was wrong. I was thinking each aspect had a coresponding signal frequency. Now it sounds to me like the frequency is a constant on any one section of track. I'm a little confused. which is it ?
I am an electronics tech, so feel free to get technical.

On a side note. I am a big fan of Nikola Tesla. I have many books on the man and his works. I have built many divices of his design including tesla coils and free energy machines. The world would be a much different place if it wasn't about the $$$ !!!

[Anonymous]

"With today's technology, why not have a "repeater" of the dispatcher's board in the locomotive's cab showing the status of all track ahead of the train."-jruppert

jruppert,
That would be way cool. Then us railfans could access this (mabee not legaly) and it would make railfanning a lot more predictable. I'm shure this is possible with todays technology, But I'm not shure if there is a real need for the crews to know "the whole picture"(now I'm gonna get it [:D] ). It would be expensive to buy and install the equiptment to do so. And this would only work in CTC territory anyway.

[Anonymous]

Dear Wisser (Chad),

Yes, the 100Hz AC freq. remains the same, it's just chopped (coded) by relay contacts that are moving (coding) at the same rate (well, as close as an electro-mechanical relay can be) as the code that is placed onto the coil of the code follower relay. WE have code transmitters that work 24hrs/day that generate the 75, 120, and 180 beats per minute. Then, by relay selection, the signal system will apply the code rate to the coil of the code follower relay depending on the route (i.e. straight move, crossover move, what's up ahead, etc). Now, when we move up to 150mph from our present 125mph, we will be going to a 9 aspect cab code system, and, we will either send out coded 100Hz onto the rails, or, coded 100Hz and 250Hz. It is intended that the 100Hz AC voltage will be connected to a pair of front contacts (hot to one front, neutral to the other), then, apply 250Hz to the back contacts. A Clear 125 (for 125mph) would be 100Hz only and coded at the 180 code rate (180 beats per minute, or, 3Hz) which is the speed the relay hinges will be moving at. For a Clear 150 (150mph - for the Acela trains only), we would run the relay at the same 180 code rate, but, 100Hz would be placed on the front contacts, and, 250Hz would be on the back contacts. During the positive duty cycle of the DC code that's placed onto the coil of the code follower relay, 100Hz would be transmitted out onto the rails (from the front contacts of the relay). During the off period of coded DC's duty cycle, the 250Hz would be transmitted out to the rails via the back contacts of the code follower relay. I found a new railroad supplier company at www.phase2concepts.com that manufactures an electronic code follower relay that features a true electronic "break before make" feature. Go there and you'll hear about a 5 second sound bite of what an electro-mechanical code follower relay sounds like. Hope this explanantion helps, I sent you e-mail inviting you to give me a call out here on the eastcoast if you ever want to talk about this in depth!

tom

[Anonymous]

For jruppert:

Yes, with cab signals on-board, it's sorta like flying with radar. You'll know what the next wayside signal will be before you can even see it.

tom

[Anonymous]

Amtrak-tom,
Thanks for the info. It makes sense now. Being a communications electronics tech, it amazes me that mechanical devices (relays) are used in these systems. In my line of work mechanical things are bad news, prone to failure. But then I guess most of that technology was probably designed a long time ago and that was the best thing they had back then. I'll check out that site when I get a chance. Again thanks for taking the time to answer my Questions.

[Anonymous]

I checked out that site and it appears that simiconductors are in fact replacing mechanical relays. The signals on there site are just what I visualised from your explaination.
Thanks again.

[tree68]

QUOTE: Originally posted by wisser

Amtrak-tom,
Thanks for the info. It makes sense now. Being a communications electronics tech, it amazes me that mechanical devices (relays) are used in these systems. In my line of work mechanical things are bad news, prone to failure. But then I guess most of that technology was probably designed a long time ago and that was the best thing they had back then. I'll check out that site when I get a chance. Again thanks for taking the time to answer my Questions.

Remember, too, that these systems predate solid state technologies, and tubes would have drawn too much power. I recall reading somewhere that the relays had /have phenomenal lifetimes.

[Anonymous]

For Tree68:

Yes, the typical electro-mechanical relay can have an exceptionally long life. But, for the Code Follower relays, they are in constant motion 24 hrs. per day. The only time they do stop is when the track circuit is occupied, or, during times of signal trouble. On the ABS territory, when you walk inside of a location house, case, etc., you hear the constant clack-clack-clack-clack of the relays coding. They wear out over time, contacts can arc, etc. It's just the nature of the mechanics. For all other relays, they'll either be sitting "at rest", or, energized in the "up" position - those will last the longest.

[Anonymous]

QUOTE: Originally posted by amtrak-tom

Marty,

I just read your profile, you worked for the UPRR? Can you answer my question posts about the cab signals used on the UPRR??

Sorry Tom,
I didn't get involved with that. Now if you ask me questions about the prime movers, brake system or trucks, those I can answer.[:D]

[Anonymous]

Thanks anyways, Drailed1999....ok, how about winning lottery numbers instead??

[Hugh Jampton]

The advantage of these type of systems is that you can do away with the lineside signals completely. The French high speed lines use a similar thing they call TVM430, and the driver has a display in the cab that gives the current speed, and the target speed at the next block boundary. There is a computer o the tain that calculates whether or not the tain will be going at the target speed when it reaches the boundary,, and if the computer thinks the train will be going too fast the the train performs a penalty stop. The boundaries are marked by a square blue sign with a yellow triangle on it. If you think about it, at high speed the tie the driver has to look at a lineside signal is very short. In the UK the minimum sighting time is 7 seconds, how far does a train travelling at 200mph go in 7 seconds?

[Anonymous]

A good discripion of coded trach circiuts including some diograms used for ATO on the London Underground can be found here. http://www.trainweb.org/tubeprune/Victoria%20Line%20ATO.htm. BTW Coded track circiuts are the system used for cab signalling as well as some ATO systems. The pricipal is the same as on Amtrak.

[Anonymous]

Thanks for your replies, people! I'm always looking for more info on this subject, i.e. who in the U.S. still have cab codes, and, who did, but, longer does, etc. The question about how far a U.K. train travels in 7 seconds at 200mph:

2,053.333 feet (0.388 mile)
1 mile = 5,280 ft.

(200 X 5,280) = feet per hour = 1,056,000 feet per hour

1 hour = 3,600 seconds

1,056,000 divided by 3,600 = 293.333 feet per second
(293.333 ft) X (7 seconds) = 2,053.333 feet traveled in 7 seconds at 200mph