Question about signal lights

[7Dave7]

Hello group,

I'm new to the group and the hobby. Just in the layout planning and general learning stage. Haven't had much chance to observe prototypical switches and signals. would like to learn about them. I'm sure signals vary from railroad to railroad or region to region.

I'd like to get a basic explaination of what signal light groupings and light colors are used in any given trackage arrangement. Links to pages with detailed explanations and pictures or drawings would be much appreciated. Actually, so would any info on the topic. I'm sure once there are some answers posted, I'll have more directed questions.  Thanks in advance to all who can provide some info or insight.    Dave J. 

 

 

[tomikawaTT]

  Welcome to the forums.

There is a truly ancient softcover book, All About Signals by John Armstrong, which at least one Class 1 railroad used as an instruction manual.  The material originally appeared in Trains magazine in June and July 1957.  This is my 'go to' source for signalling information.

There are also several pages of signal aspect diagrams in Peter Josserand's Rights of Trains, THE book for everything pertaining to rules during the transition era and before.

The third source is more, "Up close and personal."  Try to meet some of the folks who maintain and use signals.  If you can meet some railroad employees, retired and otherwise, they are gold mines of signal lore.

Since every railroad had its own standards, some of which were truly unique, you will have to choose a prototype and try to learn all there is to know about that line - or go freelance and set your own consistent standards.

Hope this has been of assistance.

Chuck (modeling Central Japan in September, 1964)

[loathar]

http://gsee.sdf-us.org/signals/siglinks/siglinks.html

Here's a whole bunch of links that might help.

[nbrodar]

Here are some basics for US signalling.   This information comes from NORAC Operating Rules, 8th Edition, effective, 1 January 2003. First some definitions.  My comments are in italics:

Block: A length of track with defined limits on which train movements are governed by block signals, cab signals, or Form D. 

Control Station: The Dispatcher's office or the location where is Operator is on duty, from which remote control signal appliances or switches are operated.

Controlled Point: A station designated in the Timetable where the signals are remotely controlled from the Control Station.  This is usually, but not always an interlocking.

Controlled Siding: A circuited siding in which both ends are controlled and governed by signals under the control of the Dispatcher or Operator.   Controlled sidings are equipped with power switches.

Non Controlled Siding: A non-signalled siding.  Entrance into or out of the siding is controlled by the dispatcher, but movement within siding is made at Restricted Speed at the discretion of the train crew.  Non controlled sidings may have powered or hand operated switches. 

Industrial Track:  A track other then Main, Siding, or Yard Track, upon which movements must be made at restricted speed.  

Interlocking: An interconnection of signals and signal appliances such that their movements must succeed each other in a predetermined sequence, assuring that signals cannot be displayed simultaneously on conflicting routes.  The tracks between opposing Home Signals of an interlocking are referred to as Interlocking Limits.

Main Track: A track designated by Timetable upon which train movements are authorized by ABS, CSS, DCS, or Interlocking Rules. 

Siding: A track adjacent to a Main Track and used for meeting or passing trains. Large industries can have their own sidings. 

 

Fixed Signal: A signal at a fixed location that affects the movement of a train.

Absolute Signal: A fixed signal capable of displaying Stop as it's most restrictive indication.  Absolute signals are NOT marked with a number plate, P or G marker.

Permissive Signal: A fixed signal capable of displaying Restricted Proceed as it's most restrictive indication. Permissive signals are marked with a number plate, P or G marker.

Block Signal: A fixed signal displayed to trains at the entrance of a block to govern use of that block.

Automatic Block Signal: A block signal that is activated either by track circuit or in conjunction with interlocking or controlled point signals.  This signal automatically indicates track conditions and block occupancy. These are normally Permissive Signals.

Controlled Signal: A fixed signal capable of displaying Stop as it's most restrictive indication, that is controlled by a Dispatcher or Operation. These are Absolute Signals.

Distant Signal: A fixed signal used to govern the approach of a train to a Home Signal. Home Signals can be Distant Signals for other Home Signals

Home Signal: A fixed signal governing entrance to an interlocking or controlled point.  These are always Absolute Signals.

Intermediate Signal: An automatic signal between Distant Signals.  These are normally Permissive.

 

Automatic Block Signal System (ABS): A block signal system in which the use of each block is governed by an automatic block signal, a cab signal, or both.

Cab Signal System (CSS): A signal system utilizing a signal located in the locomotive cab, and indicates track occupancy or condition.  Cab signals are used in conjunction with interlocking signals, are with or in lieu of block signals.  In the event of conflicting Cab and Fixed signals, the most restrictive signal will govern movement.

Central Traffic Control (CTC): A system in which signals and switches are remotely controlled by the Dispatcher or Operator.

Form D Control System (DCS): A block system, signaled or non-signaled, in which movement of trains, outside of yard limits is authorized by Form D. This is a topic for another time.

Next some diagrams illustrating all this.  Click to enlarge.

I've used the common practice of naming signals.  Controlled Points are Designated with CP -name-  Ex.  Joe and Bob are Automatic signals, while the interlockings of Nick and Dave are referred to as CP Nick and CP Dave.  

In this example, even though CP Lamp has no switches, it is still a Controlled Point, as it governs entrance into and out of Lampson Yard.   Bob is the Distant Signal for CP Nick.  Note that as there are no signals between CP Nick and CP Dave, the Home Signal at Nick is also the Distant Signal for CP Dave, and vise versa.

The London Industrial Track and Beer Siding are non-signalled tracks.  They are accessed by hand operated switches.  The switches are linked to the block signals, so that when the switches are opened or reversed, the block signals will display Restricted Proceed.

Last some Operating Rules:

Rule 251 - Track signaled in one direction: When track is signalled in only one direction, signal indication will be authority for trains to operate with the current of traffic.  Movements against the current of traffic will be governed by non-signaled DCS rules. 

Rule 261 - Track signaled in both directions: Signal indication will be the authority for a train to operate in either direction on the same track.

Note - In the above diagrams, I only included the automatic signals for movement left to right.  I accidentally left out the automatic signals for movement right to left.

Nick

 

[dehusman]

Nick covered a wide range of topics, just be aware that some of the terms may be different in other rule books and eras.

For example instead of "Form D", the western half of the country uses Track Warrants and Track Bulletins. 

CTC is called TCS on some roads.  ABS is also known as APB (there are differences which the signal experts can expound on, but in rule books they are used almost interchangeably).

Cab signals come in several varieties.  ATS - Automatic train stop, ACS -Automatic cab signals, CCS - coded cab signals, etc.

Depending on era timetable, train order or DTC (direct traffic control) were also used as main track authoirites.  In CTC, track and time and verbal authority can be used on the main track.

Rule 251 is also called "double track" or "current of traffic" and in the modern General Code of Operating Rules (almost everything west of the Mississippi since 1985) its rule 9.14 instead of 251.

Lots of variations.

Dave H.

[7Dave7]

Hello again group,

First off, thank you to those who have already replied to my first post about signals.

I need to better clarify what it is I want to know. My expreience with signals has primarily been seeing a few on Canadian ( CN & CP ) tracks, but have not had much chance to observe them when trains are near. I've also seen some on various HO layouts, but do not know if they are "operating" properly, or if they are mostly just lit up for decoration.

What I'd like to know is how many signal lights are used in a given location and in what color combinations.

 Example # 1 - a train waits on a siding to right of the mainline, near the turnout that will bring the train back onto the mainline. Is there just one signal post ahead to the right, or one to the right of the siding and one to the left of the main in this case ? How many lights on each post ? If two posts and one signal per post, I assume the one to the right of the siding would show red to stop the train and the one to the left of the main would show green if another train were overtaking and red if another train were oncoming/passing. In this case, when the sided train is clear to proceed, would the signal to the left of the mainline show red, to stop overtaking trains  while the sided train moves ont the main ?

Example # 2 - Same senario as above, but with double track main, plus a siding to the right of the righthand main. How many posts, positioned where and how many lights ?

Example # 3 - One mainline and one siding to the right. Train on mainline, approaching siding. Are there any signals on the mainline, before the train reaches the siding ? I assume so, to tell the train to proceed, or "pull over" onto the siding. If so, what color scheme to signal proceed on main and what color scheme to signal pull onto siding ?

Example # 4 - I THINK I've seen a singl post with 3 lights, mounted one above the other. How would this used ?  What combination of lights and what colors ?

Related question - Are signals at sidings normally lit all the time, or only as trains approach them ?

Lastly, do switch control motors have N switches or similar that "prove" their position and allow output form said N switches to in turn, control signal lights?    That is, if I throw a toggle switch that operates a switch motor to send a train onto a siding, can that switch motor send its own signal to control a signal light on the model ?

Thank you again to the members of the group and especially those who can assist me.

Dave J. 

  

    

 

[dehusman]

Example # 1 - a train waits on a siding to right of
the mainline, near the turnout that will bring the train back onto the
mainline. Is there just one signal post ahead to the right, or one to the
right of the siding and one to the left of the main in this case ?

What type signal system is it?  ABS or CTC?

ABS you would have signals beyond the points of the switch on the single
track, with a head in each direction.  The head for trains coming towards
the station/siding would have one or two heads.  The signal for trains
leaving the station/siding would have one head.  In ABS single track the
signals don't convey authority, just condition and occupancy.  Only one of
the signals can be anything other than all red or all dark.

CTC you would have 3 signals at the switch, one on each route into the
switch.  There would be a single head signal on the main and the siding
for trains leaving the station/siding and a two headed signal beyond the
points on the single track for trains coming towards the station/siding.
Once again only one of the signals can be anything other than all red or
all dark.

Example # 2 - Same scenario as above, but with double track main,
plus a siding to the right of the righthand main. How many posts,
positioned where and how many lights ?

Same as above only all the signals on the "righthand main", no signals on
the lefthand main.

Example # 3 - One mainline and one siding to the right. Train on
mainline, approaching siding. Are there any signals on the mainline,
before the train reaches the siding ? I assume so, to tell the train to
proceed, or "pull over" onto the siding. If so, what color scheme to
signal proceed on main and what color scheme to signal pull onto siding
?

Assume you are in CTC.  Real basics.  There are signals every 2-10 miles
all along the railroad.  The ones at siding switches, junctions and
control points are often "home" or "absolute" signals.  The ones in
between are "intermediate" signals.  Absolute signals have a plate with
the letter A on it or no plate at all.  Intermediate signals have a number
plate on them.
If the main is a high speed main (60-70 mph) they probably have a 4 signal
progression.  The signal at a stop is red.  The next signal is approach,
yellow, which means to reduce speed immediately and prepare to stop at the
next signal.  The next signal would be a flashing yellow, advance approach
(there are other variations and names) which means to slow to 40 mph and
the 4th signal would be green, clear, meaning proceed at main track speed.
 The clear lets the train go, the advance approach slows the train down so
it is under control and can comply with the approach signal  which gets it
ready to stop.

In your scenario if it is a high speed main the train approaching the
siding would get all the signals I described except that at the siding
switch they would get  a restricting/low signal (red over lunar) or a
diverging approach (red over yellow), depending on the whether the siding
was "bonded" (has occupancy detection) on it.

In ABS you would have the signal prior to the switch and regardless of the
indication (it could be clear, approach or stop) the train would stop and
line the switch and head in.  In ABS the signals wouldn't tell the train
to head in (except for those systems with a "take siding" indication), the
time table, train orders, track warrants or DTC authority would.

Example # 4 - I THINK I've seen a singl post with 3 lights, mounted
one above the other. How would this used ?  What combination of lights and
what colors ?

Mostly at interlockings or large junctions.  There are literally dozens of
combinations of red/yellow/green/lunar aspects that can be displayed
depending on what you want the train to do.  Most of the model railroad
applications only need the normal (R-R-R, Y-R-R, G-R-R) and diverging
versions (R-Y-R, R-G-R).

Related question - Are signals at sidings normally lit all the
time, or only as trains approach them ?

Varies.  Some places have
approach lit, some are always lit.  Some are approach lit but have enough
trains they seem always lit.

Lastly, do switch control motors have N switches or similar that
"prove" their position and allow output form said N switches to in turn,
control signal lights?

More or less yes.  Unpowered, handthrow
switches also have electrical switches to let the signal system know when
they are open.

Dave H.