Signaling Beyond Simple Passing Sidings

This forum is dedicated to Riding Scale Railroading with propulsion using other than steam (Hydraulics, diesel engines, gas engines, electric motors, hybrid etc.)

Moderators: Harold_V, WJH

User avatar
ChuckHackett-844
Posts: 69
Joined: Wed May 03, 2017 3:54 pm
Location: Tampa, Florida

Signaling Beyond Simple Passing Sidings

Post by ChuckHackett-844 » Sun Oct 29, 2017 11:33 pm

BigDumbDinosaur wrote:Above are the two block occupancy detectors produced by BCS Technology Limited for riding scale railroads—these items have been available since 2006.
It is my understanding that Absolute Permissive Block Signals protect bi-directional track where timetables, warrants, nor dispatch are used.

Can you link to a diagram that shows how you would use the BODs, Signal modules, etc. to implement the wiring of APB signals on a wye where there is a (right-hand running) passing siding at each apex of the wye (i.e.: 'outside' the wye) and it is desired to allow non-conflicting trains to travel all legs of the wye at the same time?

To clarify: Given wye apexes A, B, and C where each apex consists of a passing siding with a double-head signal S1 at the departure of the siding to enter the wye (facing point move on the route selection - the switch has a motor controlled by an engineer-operated toggle switch) and two single-head signals (S2 & S3) guarding the trailing-point moves from each leg (i.e.: exiting the leg to pass through the apex onto the passing siding). .. I hope that's clear.

Allowed at the same time: a train can proceed from S1a toward siding at B, from S1b toward siding at C, from S1c toward siding at A (i.e.: trains permitted to enter and travel separate legs at the same time)

Allowed at the same time: a train from S1a toward the siding at B and a train from S1c toward siding at B - when the trains get to apex B they should be be sequenced by S2b and S3b into the siding.

Not allowed: a train to be permitted to pass S1a towards siding at b at the same time as a train is permitted to pass through S1b towards siding at A (i.e.: conflicting trains).

There are no intermediate signals.

This while guaranteeing that no two trains are ever permitted into a conflicting section at the same time and it is not permitted to require a crew to backup to clear a blockage (i.e.: at large 7.5" meets people do not want to have to back up due to a red after they have been cleared into a block).
Regards,

Chuck Hackett, UP Northern 844, Mich-Cal Shay #2
"By the work, One knows the workman"

User avatar
Atkinson_Railroad
Posts: 158
Joined: Mon Jun 08, 2015 6:27 pm
Location: Michigan
Contact:

Re: Signaling Beyond Simple Passing Sidings

Post by Atkinson_Railroad » Mon Oct 30, 2017 1:53 pm

Does your term "wye" actually mean a triangle?
Your description reads somewhat similar to the famous interlocking at Fostoria, Ohio.

http://trn.trains.com/photos-videos/hot ... toria-ohio

I could be WAY off though.

Chuck, you're going to have to learn how to draw pictures so we can know for sure what you're describing. (Ha Ha : )

John

User avatar
ChuckHackett-844
Posts: 69
Joined: Wed May 03, 2017 3:54 pm
Location: Tampa, Florida

Re: Signaling Beyond Simple Passing Sidings

Post by ChuckHackett-844 » Mon Oct 30, 2017 3:51 pm

Atkinson_Railroad wrote:Does your term "wye" actually mean a triangle? .... you're going to have to learn how to draw pictures so we can know for sure what you're describing. (Ha Ha : )
:-) ... When I wrote that I was at the airport to pickup my wife and didn't have Adobe Illustrator on my laptop :-)

How's this?

Image

Note on philosophy: My interest in signals is what works best when a large number of people are attending a meet, not necessarily duplicating full-size practice. 'Scale' engineers will many times "do the unexpected" and, unlike full-size, you can't fire them :-)

This also means that I believe the system should help keep the railroad flowing as much as possible. The signal system should do some level of flow control of traffic to avoid (and hopefully eliminate) bottlenecks. This leads to such things as giving (at the railroad's option) a higher priority to clearing sidings that are "fully occupied" (multiple trains) over sidings that may have only one train on them. This is hard to do in simple occupied/unoccupied approaches.

In the example of the wye above, the system should never clear a train from Apex A onto T1 at the same time it cleared a train from Apex C onto T1 because, even if there were intermediate signals in T1 and you had "tumble down" as used by ABS signals, someone is going to have to back up and this is not acceptable at a large live steam meet. Treating the entire wye as one block would solve the issue but would reduce traffic flow because only one train could occupy the wye at a given time.
Regards,

Chuck Hackett, UP Northern 844, Mich-Cal Shay #2
"By the work, One knows the workman"

rkcarguy
Posts: 475
Joined: Tue Aug 22, 2017 10:33 am

Re: Signaling Beyond Simple Passing Sidings

Post by rkcarguy » Mon Oct 30, 2017 5:00 pm

With enough relays and diodes, one can accomplish anything!

Just kidding :) Have fun with that, I wouldn't know where to start.

User avatar
ChuckHackett-844
Posts: 69
Joined: Wed May 03, 2017 3:54 pm
Location: Tampa, Florida

Re: Signaling Beyond Simple Passing Sidings

Post by ChuckHackett-844 » Mon Oct 30, 2017 5:34 pm

rkcarguy wrote:I wouldn't know where to start.
:-) we have three of these situations at the club where I do my testing. I had to add support for this situation because, when it was one block, people were complaining that they were having to sit at red signals when they could see that it was clear for them to go (i.e.: non-conflicting trains on two legs of the wye). People are much happier now ... :-)
Regards,

Chuck Hackett, UP Northern 844, Mich-Cal Shay #2
"By the work, One knows the workman"

User avatar
Atkinson_Railroad
Posts: 158
Joined: Mon Jun 08, 2015 6:27 pm
Location: Michigan
Contact:

Re: Signaling Beyond Simple Passing Sidings

Post by Atkinson_Railroad » Mon Oct 30, 2017 5:39 pm

Okay. Very good illustration. It helps immensely.
I guess I would still label the track arrangement as a triangle (or delta : ) 3 wye's hooked together?

I'm also on the same page with you regarding your philosophy.
We'll say adopting full-size practice is a goal we can strive for some day.
(Minus firing the engineers for not studying the rule book : )

I'm wondering if borrowing a bit of "diode matrix" thinking would help in any way with this track configuration?

I'll be pondering it at the kitchen table.

John

Post Script: Pictures or visual aids accompanying [words] are always a plus!

chiloquinruss
Posts: 72
Joined: Sun Dec 16, 2007 1:39 am
Location: Chiloquin, Oregon

Re: Signaling Beyond Simple Passing Sidings

Post by chiloquinruss » Mon Oct 30, 2017 6:37 pm

We have also added in a signal or two on blind corners and/or where there is a possibility of a train ahead that is slowing down for possible switch selection. Russ

User avatar
ChuckHackett-844
Posts: 69
Joined: Wed May 03, 2017 3:54 pm
Location: Tampa, Florida

Re: Signaling Beyond Simple Passing Sidings

Post by ChuckHackett-844 » Mon Nov 20, 2017 11:38 am

BigDumbDinosaur wrote:Above are the two block occupancy detectors produced by BCS Technology Limited for riding scale railroads—these items have been available since 2006.
BigDumbDinosaur: Hopefully you are well on your way to recovery ...

You obviously have much more in-depth knowledge of full-size signal practice than I. I have come to this endeavor as a 7.5" steam locomotive owner wanting to see signals that work for large 7.5" meets ... i.e.: sometimes diverging from full-size practice where it makes more sense for meets involving engineers unfamiliar with full-size practice who can't be fired for disobeying the rules :-) ... and preventing situations where engineers might have to backup to clear a blockage (i.e.: facing each other at back-to-back intermediate red signals).

I am interested in how someone would signal the situation described and diagrammed earlier in this thread using relay-based controls (i.e.: PLCs or processors).

Can you (or anyone ...) enlighten me as to how the 'wye' situation I described would be approached using relays? I assume this would be characterized as an Absolute Permissive Block (APB) case but I'm not sure I'm using the term correctly (i.e.: protection of bi-directional traffic without the use of dispatch, timetables, etc.).
Regards,

Chuck Hackett, UP Northern 844, Mich-Cal Shay #2
"By the work, One knows the workman"

Mike Walsh
Posts: 569
Joined: Sun May 06, 2007 10:14 pm
Location: St. Louis, MO

Re: Signaling Beyond Simple Passing Sidings

Post by Mike Walsh » Mon Nov 20, 2017 11:47 am

I suggest checking out www.rrsignalpix.com -- lots of literature, and you can contact the webmaster who is very well known in the signal community. He has helped implement relay-based systems on 15" gauge railroads, and has been playing with computer-based signal systems (ElectroLogix). Send him a message and he may be able to help!

User avatar
ChuckHackett-844
Posts: 69
Joined: Wed May 03, 2017 3:54 pm
Location: Tampa, Florida

Re: Signaling Beyond Simple Passing Sidings

Post by ChuckHackett-844 » Mon Nov 20, 2017 1:00 pm

To clear up a possible point of confusion: I currently handle this wye configuration easily (we have three instances at the test RR site).

I am often told that these situations can be easily handled with simple relay-based systems (i.e.: no solid-state components). I'm looking for such examples or information on how the 'big boys' would handle these more complex cases (i.e.: beyond simple passing sidings) without resorting to dispatching, timetables, etc. to coordinate bi-directional movements.

I'm not saying that it can't be done - just wondering about how it would be done if someone wanted to.
Regards,

Chuck Hackett, UP Northern 844, Mich-Cal Shay #2
"By the work, One knows the workman"

User avatar
ChuckHackett-844
Posts: 69
Joined: Wed May 03, 2017 3:54 pm
Location: Tampa, Florida

Re: Signaling Beyond Simple Passing Sidings

Post by ChuckHackett-844 » Mon Nov 20, 2017 6:15 pm

I have been doing a bit more reading on ABS & APB signaling and I am finding statements like:

Quote from a signalling email list: "With APB the signals do not give authority for train movement. With APB the function of the signals is to provide a layer of safety to protect train movement but in no way authorizes train movement. Just because a train facing a green signal in APB territory the signal does not provide authority for the train to pass the signal. With APB and ABS too, authority to occupy main track and movements on the main track are granted by employee timetable (applicable for schedule trains only), train orders and in more modern times track warrants and direct traffic control (the latter two applicable where have direct communication with the dispatcher.

It is only with CTC that the signals provide authority for train movement. Train has a green signal the signal alone provides authority for the train to move past the signal.
"

In our use (ride-on railroads) there are no timetables, etc. so ABS/APB signal functionality (relay/slap button, etc.) as usually spoken of in relation to our hobby is not sufficient for a full-time bi-directional railroad unless it's ok to sit at a red forever because there is an opposing train and he too is sitting at a red forever.

So, it would seem that signals for this use must provide some CTC and/or Dispatcher functionality to add a measure of "Traffic Flow Control".

I have implemented this type of functionality (Traffic Flow Control) for single blocks as well as two blocks separated by a section of bi-directional single-track. An example is the wye I mentioned at the opening of this discussion:

Image

In this case I would configure S1a, S2a and S3a as a block and S1b, S2b and S3b as a block and T2 as a bi-directional single track between them. In the configuration "T2" would be listed as a "Reservation Track" for right-hand signal at S1a and the left-hand signal at S1b.

Since (in my use) a track can only be "reserved" by one signal (a double-head is two signals) at a time, only ONE of the two signals mentioned above will ever be granted a clear at any given time.

I'm guessing that this function (track reservations) is, in effect, implementing a form of CTC functionality (granting routes across multiple blocks) but I do not know enough about CTC implementations to know for sure.

I am in the process of extending this functionality to allow a signal to reserve multiple track segments (a current customer requirement) but, in the future this will be extended to a concept of reserving "routes" from one arbitrary point to another. These "routes" would protect a train against opposing traffic [conflicting traffic] as it passes through multiple blocks/junctions/intersections while allowing for merging traffic [non-conflicting traffic]. Not easy, but, to me, required for larger railroads that have many route choices and want to be full time bi-directional - examples

Central Pasco and Gulf Railroad https://www.dropbox.com/s/q4cf5j83yzwvr ... .jpg?raw=1 and
Ridge Livesteamers http://www.ridgelivesteamers.org/new_trackplan.htm

Chuck
Regards,

Chuck Hackett, UP Northern 844, Mich-Cal Shay #2
"By the work, One knows the workman"

User avatar
ChuckHackett-844
Posts: 69
Joined: Wed May 03, 2017 3:54 pm
Location: Tampa, Florida

Re: Signaling Beyond Simple Passing Sidings

Post by ChuckHackett-844 » Mon Dec 11, 2017 3:39 pm

BigDumbDinosaur wrote:Above are the two block occupancy detectors produced by BCS Technology Limited for riding scale railroads—these items have been available since 2006.
From time too time I'm told that my approach to signals is overly complex and that it can be done much simpler. For "Train Separation" (i.e.: uni-direction with following trains) I agree.

When you get into bi-directional running, I assert that ABS/APB signals are not sufficient without requiring someone to back up in the case of APB conflicts (e.g.: meets at intermediate signals - not desirable at a large meet). Further, managing traffic flow and preventing deadlocks requires using a) a dispatcher, b) timetables, c) track warrants, etc. (which is not practical for 90% of ride-on railroads).

BigDumbDinosaur: Since you have dealt with ABS/APB signals extensively - am I wrong in this? How (as an example) would one signal a Wye using only ABS/APB signals to support bi-directional running? (for complete description of the requirements see my initial post in this thread and the clarifications that followed - the diagram, etc.)
Regards,

Chuck Hackett, UP Northern 844, Mich-Cal Shay #2
"By the work, One knows the workman"

Post Reply