Railroaders' Nostalgia > Remembering SPRR LA Division First Automatic CTC Machine

As an SPRR Train Dispatcher from September 1971 to June 1974 I had the "privilege" of working all dispatching positions at SP's Los Angeles Division Train Dispatcher's Office, located at 6th and Main in downtown LA.  During this timeframe, the "newest" and most modern CTC machine in this office was the machine that controlled the territory between Indio, California and Yuma, Arizona.  This Centralized Traffic Control (CTC) machine was one of, if not the first, "automatic" CTC machines on the SPRR.  Although my photo of the machine is not the best, it does show us the details of the machine and the portion of the railroad between Indio and Niland, California.  In the photo we see the double track heading east out of Indio to Thermal and the dispatcher has a train lined through Thermal.  There's another train (probably the empty ore gons) going through Mortmar and lined into the Ferrum Yard where the SPRR interchanged with the Eagle Mountain RR that served the iron ore mine at Eagle Mountain.  The top row of toggles lined the switches (green for normal, orange for reverse), the second row of toggles lined the signals (red for not clear, green or yellow for clear).  On this machine there was a third row of toggles that put the machine into automatic (green for on and dark for off).  The automatic toggles were located at each end of a siding.  When the dispatcher didn't have to worry about priority of trains, she or he could put all or some of the sidings into "automatic" and the machine would do the rest. In the photo we see the dispatcher has the machine in automatic at all sidings except Ferrum, where the train is going into the yard and at Thermal where the next eastbound is lined through.  The automatic portion of the machine was a simple logic.  If two trains were operating in an opposing direction from each other, the first train to go across the last switch prior to the next switch of the next siding, would result in the machine reversing that next switch for the train and lining the train into the siding.  The opposing train would have a stop signal at that switch until the first train cleared the main track.  The machine would then normal the switch, line the signal to clear and the opposing train would continue its journey.  Once the opposing train cleared the other end of the siding the machine would reverse the switch and line the signal to clear to permit the train that went into the siding to continue its journey.  Pretty simple, but, again, no perspective of priority when in automatic mode.  If there were no opposing trains, it was even better as the machine would just clear signals in the direction of the train movement, which made it easy for the dispatcher if there was a fleet of trains in either direction and no meets involved.  This "East End" machine was paired with the "West End" (Los Angeles to Colton) machine in this timeframe and known as the "Monster".  As a dispatcher, you could get very busy on the west end and kind of forget about the east end while having the east end in automatic.  I learned the hard way once about the automatic capability when the hottest train on the SPRR, the "Blue Streak", called me on the radio and wanted to know why they were lined into the siding at Acolita.  Oops!  Automatic feature had failed and lined the train into the siding for no reason!  I told the BSM crew I had a track indication on the main at Acolita and all was good!

Pete
Clio, California

---

Fascinating photo and description - Thanks for posting this.   When I was a boy of about 10-12, my neighbor (in Lima, Ohio) maintained the CTC machine for the NKP. I remember him taking me and my Dad down to the dispatcher's office one evening to see it.   To say I was impressed is an understatement.   This would have been sometime in the late 50's or early 60's, and the specifics are lost in my memory.

One question I'd like to ask - were the panel controls individually wired to a single switch or signal with it's own wiring, or was there some form of addressing that was used to allow a common "bus" (if I can use that term) to reduce the amount of wires that were needed.  I assume that the automatic processes you described was handled by a set of relays. 

Thanks again

JWL

tbdbitl Wrote:
-------------------------------------------------------
> Fascinating photo and description - Thanks for
> posting this.   When I was a boy of about 10-12,
> my neighbor (in Lima, Ohio) maintained the CTC
> machine for the NKP. I remember him taking me and
> my Dad down to the dispatcher's office one evening
> to see it.   To say I was impressed is an
> understatement.   This would have been sometime
> in the late 50's or early 60's, and the specifics
> are lost in my memory.
>
> One question I'd like to ask - were the panel
> controls individually wired to a single switch or
> signal with it's own wiring, or was there some
> form of addressing that was used to allow a common
> "bus" (if I can use that term) to reduce the
> amount of wires that were needed.  I assume that
> the automatic processes you described was handled
> by a set of relays. 
>
> Thanks again
>
> JWL

The word you're looking for was "multiplexed". Multiplexing allowed one pair of wires to carry multiple commands at a time.

Great post Pete. I picture the late Mike Chavez sitting in the chair smoking a cigarette and snapping the buttons. Wonder what happened to the CTC machines ?

Posted from Android

SP replaced them with computers in the 90s

Zephyr Wrote:
-------------------------------------------------------
> As an SPRR Train Dispatcher from September 1971 to
> June 1974 I had the "privilege" of working all
> dispatching positions at SP's Los Angeles Division
> Train Dispatcher's Office, located at 6th and Main
> in downtown LA.

I worked Bakersfield 1972-1973. I might have listened to you on the monitor speaker when working the Saugus job.


> During this timeframe, the
> "newest" and most modern CTC machine in this
> office was the machine that controlled the
> territory between Indio, California and Yuma,
> Arizona.  This Centralized Traffic Control (CTC)
> machine was one of, if not the first, "automatic"
> CTC machines on the SPRR.

Tucson and Bakersfield had the next generation:
Tucson fixed link: http://rrsignal.com/photos/displayimage.php?album=43&pid=1369#top_display_media and http://rrsignal.com/photos/displayimage.php?album=43&pid=1376#top_display_media and http://rrsignal.com/photos/displayimage.php?album=43&pid=1390#top_display_media
Bakersfield, Fresno-Lathrop fixed link http://rrsignal.com/photos/albums/union_switch/c_books/sp/9153.jpg
 by the time I worked this, it had a second level, like the Tucson machine, handling Stockton (Akers?)- Polk
Bakersfield, Fresno-Bakersfield fixed lkink http://rrsignal.com/photos/displayimage.php?album=43&pid=1397#top_display_media
 and this one had a second level added for Sandcut - Tehachapi

> The automatic toggles were
> located at each end of a siding.  When the
> dispatcher didn't have to worry about priority of
> trains, she or he could put all or some of the
> sidings into "automatic" and the machine would do
> the rest.

The Bakersfield machine had a hot train feature that would look two sidings in advance of a train that had it turned on. It was the best CTC I worked. Once you got used to it, you could think like it was train orders. If you didn't want a train to get past a location, turn off the automatic there. If you wanted a train to go at least so far, line a signal and put that station back on automatic.If part of the railroad was DOFTs (Dirty Ol' Freight Train), and everybody fit (not a problem between lathrop and Bakersfield at the time), but you had a sticky situation brewing somewhere else, put the part that could take care of itself on automatic and run the sticky place, whether a siding or two or several in a row, on manual. That's pretty much the way a busy train order railroad was worked.  I liked them a lot more than the computerized stuff BN was using before I left.

There wa a steel gang between Roseville and Stockton while I was there. At 6pm when they called it a day after 12 hours, Then came the flood - 12 hours of trains plus the normal traffic - 20 or more trains between 6p and quitting time at 11p. I was so thankful for knowing how to use the automatic to my advantage.

TAW



Edited 1 time(s). Last edit at 02/27/21 09:21 by TAW.

TAW, your links don't work - access denied is the message I get.

WAF Wrote:
-------------------------------------------------------
> SP replaced them with computers in the 90s


I remember was on duty that particular day. Trying to recall the location and circumstances. I remember hearing the SP Dispatcher Marla Conti, give us block authority in DTC territory for the last time. I knew Marla as a child growing up. It was bitter sweet the last of the SP dispatching.
Wes was wondering where did the CTC machines end up in whose possession? In a museum? Or a rail fans garage?

Posted from Android



Edited 1 time(s). Last edit at 02/27/21 12:28 by SanJoaquinEngr.

I kniow a couple ended up in fans hands. Others? Good question. Trash, storage rooms? Who knows. Tucson station museum has the board for Tucson to El Paso, I believe

About the time of thew SP-DRGW merger, Digicon was in pace on the DRGW and SP adapted it. Old DS heads had lots of trouble understanding those new computers and cussed openly on the radio when doing track and time

Railbaron Wrote:
-------------------------------------------------------
> TAW, your links don't work - access denied is the
> message I get.

I tried bypassing too much of their menu system for everyone's convenience. After some experimenting, I found the place I need to stop going deeper before getting the link. Fixed now.

TAW

I am not confident in my understanding of the "back room" associated with these CTC machines.  I do know relays were used in the automatic process and multiplexing allowed many commands to be issued at once, but, when it was busy, and there were many commands being issued through normalling or reversing switches and clearing signals, the relays couldn't keep up with it.  Lots of "clicking" of relays could be heard on the machine, which were carried by wire to a relay room in the back of the dispatchers office.  I believe the commands were then forwarded by a microwave system to the field, but I could be wrong.

Zephyr Wrote:
-------------------------------------------------------
> I am not confident in my understanding of the
> "back room" associated with these CTC machines.
>  I do know relays were used in the automatic
> process and multiplexing allowed many commands to
> be issued at once, but, when it was busy, and
> there were many commands being issued through
> normalling or reversing switches and clearing
> signals, the relays couldn't keep up with it.

The system polled every control point in order, one end of the district to the other and start over. If anything was different from the last contact, an indication code would come back to the machine.

Control codes, instructions from the machine to the field, interrupted the polling process. It didn't even take changing anything, just pushing the start button for a location. The control code would go out, stopping the receipt of indication codes. If you lined up a bunch of locations, after they all went to the field, the indication codes would catch up. A guy in the roseville office told me about a boring night game some of them played with the machine handling Santa Marguarita. As soon as a train hit CTC, they would keep pussing a start button until the train left CTC, then stop. The indication codes would catch up, giv ing the train a WARP 9 trip across the territory, which was reflected as such on the graph.



>  Lots of "clicking" of relays could be heard on
> the machine,

That was the coder generating the series of long and short pulses that represented location id and the positions of switches and signals.

Some machines I worked had a pair of monitor lights for code line activity, one for indications, constantly flashing as the machine polled locations, and one for controls, lit only when the machine was sending a code to the field. They would be helpful if there was signal trouble.


> which were carried by wire to a relay
> room in the back of the dispatchers office.  I
> believe the commands were then forwarded by a
> microwave system to the field, but I could be
> wrong.

Depending upon where wire or microwave or microwave part of the way and wire on the ends.

TAW

WAF Wrote:
-------------------------------------------------------
> I kniow a couple ended up in fans hands. Others?
> Good question. Trash, storage rooms? Who knows.
> Tucson station museum has the board for Tucson to
> El Paso, I believe

The US&S CTC machine that controlled West Yard in Yuma to Stockham in Tucson is on display at the Tucson Amtrak station.

SP Yuma to Tucson CTC Machine

tbdbitl Wrote:
-------------------------------------------------------
> Fascinating photo and description - Thanks for
> posting this.   When I was a boy of about 10-12,
> my neighbor (in Lima, Ohio) maintained the CTC
> machine for the NKP. I remember him taking me and
> my Dad down to the dispatcher's office one evening
> to see it.   To say I was impressed is an
> understatement.   This would have been sometime
> in the late 50's or early 60's, and the specifics
> are lost in my memory.
>
> One question I'd like to ask - were the panel
> controls individually wired to a single switch or
> signal with it's own wiring, or was there some
> form of addressing that was used to allow a common
> "bus" (if I can use that term) to reduce the
> amount of wires that were needed.  I assume that
> the automatic processes you described was handled
> by a set of relays. 
>
> Thanks again
>
> JWL

When I went to Lima in December 1976 this machine was still there, now Norfolk and Western, Muncie Division.  It controlled from the former NKP mainline just west of Fostoria, Ohio, to Frankfort, Indiana, on what had been the Lake Erie and Western.  Some time after the 1978 BRAC strike the dispatchers office was consolidated into the Muncie Division office in Muncie, Indiana, in a new, small building with new "state of the art" equipment.  The Muncie office had controlled the non-CTC part of the division and the Chief Dispatcher was located there.  Later when the Muncie Division was split up dispatching was done from Fort Wayne.  I don't remember an automatic feature, but there were "Call" buttons on the lower part of the panel that activated a light in the field to request a train or maintenance person contact the dispatcher.

As I recall there were bundles of wires behind the panel with individual wires going to each control on the panel.  

Thanks for all the information in this thread, including the information on "Automatic" CTC which I had not heard of.

Jim

The machine in my photograph also had "maintainer call buttons" on the very bottom below the automatic/send toggles.  When the dispatcher flipped these toggles up and pressed the "start" toggle (also known as the automatic toggle) a white light on the side of the CTC box at the designated siding would light up and the maintainer would know the dispatcher needed to converse.  These were very handy when you couldn't reach the maintainer by radio.

Zephyr Wrote:
-------------------------------------------------------
> The machine in my photograph also had "maintainer
> call buttons" on the very bottom below the
> automatic/send toggles.

Those were common until something like the late 70s, when so many were shot out or otherwise vandalized that the function was worthless.

TAW

TAW Wrote:
-------------------------------------------------------
> Zephyr Wrote:
> --------------------------------------------------
> -----
> > The machine in my photograph also had
> "maintainer
> > call buttons" on the very bottom below the
> > automatic/send toggles.
>
> Those were common until something like the late
> 70s, when so many were shot out or otherwise
> vandalized that the function was worthless.
>
> TAW

Years ago I was in a siding waiting for a signal.....and getting nothing we tried to tone the DS.....no answer tone was heard so we reckoned radio trouble....by and by a light came on at the signal shack....I thought...hmmmm maybe the power has been out and now it's coming back......sure enough the DS hollered at US....to see where we were....the power was indeed up, but the codes were not arriving at the interlocking....we had to take permisson to line ourselves out....and proceed. That old signal system was fine it's day...but held together with bailing wire and bubble gun towards the end. 

In the ealry 2000s the old "Model Boards" (track diagram plates) for the SP Aurant to Colton CTC machine, which had passed down from Asst. Signal Supervisor Gene Cox to his son Bruce (both now deceased), were donated to the R&LHS at Pomona, CA, and were to be a part of their exhibits.
What made CTC practical was the Code Line for multiplexing.  Developed before WW2, it used relays, and there was always a rhythmatic background of them in those CTC offices.
Without multiplexing, there would have to be a copper wire for each function at each location, over distances of tens to hundreds of miles; the world would run out of copper before CTC could have been completed.
One important thing to remember about CTC: it is a supervisory machine which means it can request the alignment of switches or clearing of trains but not command them.
Each local interlocking (Control Point) has its own safety functions.  It cannot clear a signal or line a switch unless and until there are no indications or track occupancys that would cause a conflict or unsafe condition.
For example, if Zepher requested that the west switch at Ferrum be restored to normal for that eastbound coming out of Thermal to go further east, it will not actually line the switch until
1. The Ferrum empties are off of the OS circuit and fully in the siding
2. There are no other track occupancy indications on the OS circuit or on the main track between switches at Ferrum
3. The switch points have moved fully over to the normal position and the locking rods are fully inserted inside the switch machine.
If 1,2, and 3 are in effect, then the eastbound signal can display a proceed indication and Zephyr's request will be acted upon.