RAA49I am a volunteer at the Arizona Railway Museum in Chandler, AZ. In our collection we have a Centralized Traffic Control Panel which from the late-1950s to the mid-1980s controlled Southern Pacific traffic, first between Tucson, AZ and Lordsburg, NM and later between Tucson and Anapra, NM, just outside of El Paso, TX. This CTC system was manufactured by Union Switch & Signal. The system doesn’t use the rotary switches common on CTC system from the 1920s and 1930s, but uses a centralized set of push buttons, which can be used to control all switches and signals. Manufacturer’s pictures of the system in its Tucson to Lordsburg days are available on the http://rrsignal.com web site. An overview of the panel is shown in: http://rrsignal.com/photos/displayimage.php?album=43&pid=1349#top_display_media A closeup of the control panel can be seen at: http://rrsignal.com/photos/displayimage.php?album=43&pid=1352#top_display_media A single section of panel can be seen in the following picture: http://rrsignal.com/photos/displayimage.php?album=43&pid=1353#top_display_media We are currently working on making the panel look as it did during operation. We can now control all 1150 light bulbs on the panel under microcontroller command. The issue is, we are not sure how the system looked during operation. There are two issues. Blue lights at the switch positions shown the switch position, but does a blue light show where the train will go or where the train is blocked from going? Second, how many of the lights on the panel are on at any one time? For each signal there is a red and a green bulb. Is one or the other always on, or do they only show when a train is near that position, or do they only show when the dispatcher is setting the state of that signal and switch? Similarly, for the blue bulbs which show switch positions, is one of the two always on, or do they only light when that switch is being controlled by the dispatcher? The panel looks very festive with lots of lights on; but is that a realistic portrayal of how the panel looked during operation? Any help with this would be appreciated. Access to a user’s manual for the CTC would be wonderful.
Never worked with that form of CTC machine. Close up of the Control Panel is not 'close enough' to be able to read the labels on the 'keyboard' to understand what function(s) they are commanding.
If you notice, each Control Point 'EE Fender' etc at the top of the panel has a number associated with it '20' in the case of EE Fender. The Dispatcher will initiate what ever actions he wants to take at EE Fender by, in some manner, accessing 20 on his keyboard, he will then have the machine 'send a code' to that Control Point to manipulate the switch, the switch when it comply's with that command it will send a acknowledgement back to the machine. The Dispatcher will initiate actions to send a code to line the signal over the route, when the signal lines it will send a acknowledgement that the signal has been lined - what color lights are used on the model board for any of these actions are unknown to me. Dispatchers must know that the codes that have sent have been acknowledged to KNOW that the requested action has taken place.
As trains move across the model board they will turn on 'track occupancy lights' as they move from one track segment to the next. A 'track light' staying on AFTER the train is known to have exited the track segment is a primary indication of a track or signal malfunction. The malfunction could be either a broken rail or a broken track bond wire - trackmen fix broken rails, signalmen fix bond wires - On most properties both crafts are notified of the track circuit remaining on.
The most elemental form of CTC signal failure that the Dispatcher will notice is that he sends a code for an action to the Control Point and he never gets a acknowledgement in return. That is basically known as 'Code Line Failure'.
Never too old to have a happy childhood!
we have a small version of one of these in our Museum. It is actually using the old equipment to generate the code. There is microprocessor that is the "switch" or signal to send and aknowledge code back to the CTC.
So when you punch up the location on our console you are setting relays then when you punch to change the switch position the realys take off sending out the code, once acknowledge code comes back lights on console show change in signals and siwtch position for route ect.
Thank you for your reply. It confirms a lot of what our understanding on the working of the panel . What we are still not certain of is what lights are lit when a train is not close to a particular Control Point, such as the EE Fender that you use as an example. Will the lights that show switch position always be on, even if there is not train anywhere near that Control Point. Similarly for the signal lights. If there is no train near the particular Control Point do the signals still illustrate red or green? One person that I am working with feels that if lots of lights were on much of the time it would be too confusing. My feeling is that the dispatcher would want to know what the conditions of switches and signals were all the time. Any insight on that?
Thank you for your reply. The system that you have in your museum sounds interesting. I believe that you have a larger percent of the original system than we have. I don't believe that we have any of the original control relays in our system. They were all in relay cabinets a floor below where our control panel was located, and those parts of the CTC were scrapped. The museum only got the console, nothing else.
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