# ABS to CTC signaling



## Overkast (Jan 16, 2015)

I am starting to plan for a signaling future on my layout, and the ideal end-goal would be a healthy mix of ABS and CTC controlled signals. 

Obviously signaling is expensive, so I want start off small with maybe 2 signals controlled as ABS and would like to grow the system eventually into CTC as I can afford more. I will block my tracks now, to prepare for the CTC future, I just can't invest in all the signals right now at once.

I'm having a hard time finding comprehensive resources out there on signaling, so my question is, is it easy to start with ABS and then expand to integrate CTC into the system later / over time?


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## DonR (Oct 18, 2012)

Not familiar with ABS and CTC that you mention.

However, I see a Florida Club that models N scale
and sets up a big modular layout at train shows.

They have operating signals and in addition, their
system actually controls the DCC locos. 
When a train passes in to a 'block' the immediate
signal goes red, the next signal BACK goes yellow.
When the loco goes into a block with a yellow signal
it will slow. When it encounters a Red, it will stop.

I hope to see that layout Saturday April 9 at a train
show. I would like to find out what they use for
train detection as well as what computer program
they use to send the DCC signals to the locos.

I hope to be able to pass along this information to
the forum.

Overcast. I assume what I described is what you
want to do. Right? It is fascinating to watch.

Don


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## Overkast (Jan 16, 2015)

Hey Don, thanks for the reply, I really appreciate it.

Yes, what you speak of is eventually where I want to get to! It would be awesome to have a layout that kind of governs itself like that (just from a collision-proof standpoint).

The idea of ABS is that the signals automatically change when a train occupies a block, but integrating automated train speed controls into that signaling system is even better than just the lights turning colors.

CTC refers to manual controlling of signals (and even turnout switching) on the layout. It's like working in a control tower and changing routes from a computer program (like JMRI).

All of my turnouts are currently manual-thrown using DPDT slide switches, and I also control the frog polarity using those slide switches as well. So I imagine to have a setup like the Florida layout you speak of, to have full ABS and CTC integration working most efficiently, I would eventually need to control all turnouts using automated servos controlled by the JMRI interface as well.


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## JerryH (Nov 18, 2012)

You may find this interesting as there was a progression in the signaling control from manual to computer control.
http://www.modeltrainforum.com/showthread.php?t=14852


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## DonR (Oct 18, 2012)

JerryH has a good insight for model electronics and
could be a real help in what you want to do.

I hope to know more after the 4/9 train show. But
I understand that you'll need to establish isolated
'blocks'. I've read of sensors that detect the loco
power draw in them and cause the signal system to change.
The progressive nature of the signals I've seen 
would require fairly complex circuits or computer
control. And the
additional actual loco control is something else again.

I once designed and built a relay circuit intended to
start and stop HO trolley cars at street corners. Each
car had a magnet that tripped buried microswitches
which controlled the relays. I had isolated blocks 
they controlled to additionally prevent rear end
crashes. It worked too well. It
quickly cycled through all the stops and shut down. I didn't get beyond that after a bad roof leak destroyed the
layout.

Don


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## Overkast (Jan 16, 2015)

Jerry, thanks for the link to the thread. I am doing lots of reading in there in hopes your experience will teach me some insight as to my own plans...


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## gregc (Apr 25, 2015)

Overkast said:


> Obviously signaling is expensive, so I want start off small with maybe 2 signals controlled as ABS and would like to grow the system eventually into CTC as I can afford more. I will block my tracks now, to prepare for the CTC future, I just can't invest in all the signals right now at once.


I don't believe the way you would block the railroad or the type of signals would be any different.

Automatic Block Signaling controls the signal aspects depending on the blocks occupied by trains detected by occupancy detectors.


Central Traffic Control system controls signals partially manually by a dispatcher with some automation such as clearing signals (or dropping them to approach) once a train has moved through a block.

An ABS system would be fully automatic using occupancy detectors and turnout position sensors, some logic circuits and signals. Some signals may require manual operation at a particular junction. But then there would be verbal communication between operators at each junction to know when signals can be cleared.

CTC would normally be implemented using a PC able to sense the occupancy of train blocks, update some type of display board (LEDs or graphics) and allow an operator to control turnouts and signal aspects.

The Pacific Southern has such a CTC System


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## dave1905 (Jul 7, 2013)

Straight ABS and CTC are both the same and different signal systems. The aspects and indications may look the same but they are different and the "same" situation will have different indications between the two. ABS and CTC are the same between siding and junction switches and very different at siding and junction switches.

In ABS the signals convey movement information in the block ahead. In CTC the indications authorize movement, in ABS something else has to grant authority (schedule, train orders, track warrants, current of traffic, DTC authority, etc).

In ABS, at the end of a siding, there will be a signal for each direction on the single track beyond the switch. The switch will be hand operated. You will never get a diverging indication coming up to a siding switch in ABS. You don't get a leaving signal out of the siding in ABS, you get a leaving signal for the block on the main. If you have to clear the main track at a siding in ABS and the signal at the end of the siding you will use displays stop, you can pass the stop signal (after stopping) with out permission to open the switch and head into the siding. If you are at a siding in ABS and the leaving signal is green, you can't leave unless your track authority permits you to leave.

In CTC, at the end of a siding, there will be a switch at each entrance to the switch governing movement over the switch and into the next block. The switch will be dual controlled. You can get a diverging indication coming up to a siding switch in CTC. You do get a leaving signal out of the siding in CTC. If you have to clear the main track at a siding in CTC, the switch and the signal will be lined to authorize your movement into the siding. If you come up to a signal displaying stop in CTC, you can't pass the stop signal with out verbal permission of the control operator. If you are at a siding in CTC and the leaving signal is green, you can leave unless, it is your authority permits to proceed.

Having said all that, most model systems aren't on layouts long enough to do a full signal system and most modelers aren't savy enough to realize the differences between the two systems. I tell people (especially those using TWC or DTC without cabooses, i.e. modern) to just pretend they have ABS. Mostly what ABS does is help prevent two trains from running into each other, mostly one rear ending the other. If ABS prevents a head on then a whole lot of other stuff has failed.

If you want to do CTC, you are probably better off doing a CP at a time in CTC right from the beginning.


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## Overkast (Jan 16, 2015)

Do you think it's a realistic expectation that I can have just an ABS signaling system hooked up to manual DPDT slide switches for turnouts, and forget about CTC altogether? So in theory, the "CTC" factor is just me throwing turnouts manually, and the ABS is used just for block detection, detecting / reacting to turnout positioning, and preventing collisions through automated speed reduction?


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## DonR (Oct 18, 2012)

My brother has installed trackside signals at his
mainline turnouts. He uses the built in switches
on the Tortoise motors to control the Red/Green/Yellow
LEDs in the signals.

I control my panel LEDs using a DPDT switch,
one side determines point position the other side
controls the Panel LEDs, but the points don't
move until i push a button. That is awkward and
not a certain switching method.

The best solution for this is the Stapleton 751 D
switch that does both and includes a built in
Capacitor discharge Unit.

Don


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## gregc (Apr 25, 2015)

what I haven't been able to figure out is how a completely automated system handles signals when a train is moving in different directions on a single track.


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## Overkast (Jan 16, 2015)

I'm starting to think realistic signaling is a pipe dream for me, at least right now. Been reading a lot more about it - very expensive, complicated, and half my layout track was put down without "blocks" in mind. I really don't want to rip up a bunch of track only to put in plastic rail joiners to block it off. Plus, seems like overkill for a 8'x4' layout anyway...

If one day i decide to get into it, I may rely mostly on IR and photosensor technology for signal control...


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## cv_acr (Oct 28, 2011)

Overkast said:


> Do you think it's a realistic expectation that I can have just an ABS signaling system hooked up to manual DPDT slide switches for turnouts, and forget about CTC altogether? So in theory, the "CTC" factor is just me throwing turnouts manually, and the ABS is used just for block detection, detecting / reacting to turnout positioning, and preventing collisions through automated speed reduction?


Until you got to the "and preventing collisions through automated speed reduction?" part that describes the concept behind ABS to a T.

But the signalling does not control the trains, the engineer does but he uses the signal indications much the same way stop lights don't control your car, but you control your car based on the light indications.

CTC gets added on top with certain switches and signals remotely controlled by the dispatcher, and a bunch of normal automatic signals in between.


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## cv_acr (Oct 28, 2011)

gregc said:


> what I haven't been able to figure out is how a completely automated system handles signals when a train is moving in different directions on a single track.


It doesn't - nor does it really need to...

ABS only shows track occupancy and switch position information. As mentioned before, there is no "fully automatic" system that actually gives trains permission to move.

With CTC, there are certain signals at certain points which are dispatcher-controlled, which he/she can set to allow movement.

Without CTC, some other form of giving trains permission to move (usually by formal orders over the radio) is required, even with ABS signals. 

The ABS signals only give status information, they don't really "control" anything.


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## gregc (Apr 25, 2015)

cv_acr said:


> ABS only shows track occupancy and switch position information. As mentioned before, there is no "fully automatic" system that actually gives trains permission to move.


the image below shows how the signals in each direction depend on the direction of the train. The signal in front of the locomotive is clear and the signal following is approach.

Railroad Operation and Railway Signalling has diagrams showing signalling circuits that aren't trivia.


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## DonR (Oct 18, 2012)

The fully signalled N Scale modular club layout that I have seen
at train shows does control the trains. they slow on yellow
and stop on red. However,
they have a double track main and traffic is in
one direction on each.

Don


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## ED-RRR (Jun 4, 2015)

*CTI --> Automated Train Operations..*

*CTI Electronics..*
http://www.cti-electronics.com/

Using CTI hardware and software can "Fully Automate" a model train layout.. 
I am presently installing a CTI system to control all of my "Track Signals"..

*Caution:*
Yes it can become quite expensive ($'s) when looking at the required electronic components..
Being a very powerful automated system requires many different electronic components..

For My Track Signals:
"Train-Brain" Control Module --> sends software information to P.C..
"Sentry" Control Module --> receives signals from train detection units..
"SignalMan" Control Module --> controls train signal lights..

*Warning:*
Being a very powerful automated system requires "Advanced P.C." programming knowledge..

*Crossing Gate Program Sample:*

*......................*
Controls: CrossingGate
Sensors: OuterSensor#, InnerSensor*~
Signals: Flasher(2)

Actions:
When OuterSensor = True Do
CrossingGate = On
Wait Until InnerSensor = True Or OuterSensor = False Then
Wait Until InnerSensor = False Then
CrossingGate = Off 

While CrossingGate = On Do
Flasher = "*-", Wait 1,
Flasher = "-*", Wait 1
*..........................*








......


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## ED-RRR (Jun 4, 2015)

*CTI --> "Fully" Automated Train Operations..*



cv_acr said:


> As mentioned before, there is *no "fully automatic" system* that actually gives trains permission to move.


Sorry [cv_acr] because my intention is not to prove you wrong, but to only update an actual fully automated software model train program..
As stated, I actually have CTI modules and know how the system fully functions..
With the ulimited "Variable" software programming, there are "No" limitations what can be done.. 
The CTI system transforms your personal computer into a sophisticated "Centralized Traffic Control" (CTC) facility..

http://www.cti-electronics.com/whatscti.htm







......


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## DonR (Oct 18, 2012)

DonR said:


> The fully signalled N Scale modular club layout that I have seen
> at train shows does control the trains. they slow on yellow
> and stop on red. However,
> they have a double track main and traffic is in
> ...


I was wrong. Talked to a member of the Orlando N scale
club last week that operates this huge modular layout at train
shows. He said electronics engineers in their membership
designed a current draw block detection system and
progressive signalling, but it does not control the locos.
Members must do that. 

Don


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