Is there a definitive guide for the signal lights for US railroads? I've found a lot for Canada and Europe but nothing that's consistent for US railroads.
You'd have to read the signals section in each individual rulebook. The U.S. has several, including the GCOR, USOR and NORAC. Canada only has one (CROR) but each railroad has their own version that differs slightly, for example CP uses some unusual signal indications that are not found in the CN CROR.
Greetings from Alberta
-an Articulate Malcontent
A good reference chart source:
https://signals.jovet.net/rules/index.html
As has been noted - each railroad has their own schema. Sometimes they are at cross purposes - a given indication means one thing on one railroad, and something different on another. This has led to problems, like the engineer in the Chicago area who applied the wrong rule and ended up rear-ending another train.
But, a few rules of thumb you may find useful. Red usually means stop. Amber usually means slow down. Green means go. Lunar (light blue) usually carries some special meaning. The following examples are just that.
If there are stacked signals, the top signal generally applies to track speed. Hence the term "high green."
The middle signal refers to medium speed. A train seeing a green signal in the middle of three heads will be proceeding at medium speed, often through some form of interlocking.
The bottom signal refers to slow speed. Kind of like the middle head, it's often an indication of some sort of interlocking, like a diverging route.
There are "always" three heads at an interlocking. If there are only two, the bottom is assumed to be red (any head not displaying another aspect will be red. Sometimes you'll see three heads of which the top one is always red, because there will never be a track speed indication given.
There are also flashing aspects. Consult your favorite railroad's rule for explanations.
As I said, though, these are very general "rules" - not something to live or die by.
I should also note that many (most?) signal systems are speed, not route. The key is understanding a given plant and knowing that such-and-such aspect generally means that a certain action or routing will be involved.
Signal rules tend to be quite intense - get some basics down and you'll know enough to fan knowledgeably.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
Are the signal lights turned off to extend the lamp life or does it have some other significance?
In the following clip, there are lights on the outsides of the double track. When the train triggers the lights, both sets switch on. The one on the right has an orange light which would mean to go slow. Is this for a train that would be on the right-side track?
https://youtu.be/GVVYFLQESZs?t=60
If so, why would the train on the right-side track have a speed restriction?
The answers here helped me use better search terms which led me to the following site.
http://www.mikeroque.com/railroad-signals/
Perry BabinAre the signal lights turned off to extend the lamp life or does it have some other significance? In the following clip, there are lights on the outsides of the double track. When the train triggers the lights, both sets switch on. The one on the right has an orange light which would mean to go slow. Is this for a train that would be on the right-side track? https://youtu.be/GVVYFLQESZs?t=60 If so, why would the train on the right-side track have a speed restriction? The answers here helped me use better search terms which led me to the following site. http://www.mikeroque.com/railroad-signals/
There are two methods of for the display of signals - Constant Lit or Approach Lit.
With Constant Lit the signals stay lighted all the time and display whatever signal indication the Automatic Block Signal system demands that it show.
Approach Lit signals only come on when a train activates the track occupancy circuit that approaches the signal, otherwise the signal stays dark.
In territories where signals govern multiple track - those signals will display the required Automatic Block Signal indications for ALL tracks - if the signal system is Approach Lit all the signals will turn on to display the indications when the track circuit approaching the signal location becomes occupied by a train moving in either direction.
In general - there is a progression for the signal indications that get displayed to a train. In its simplest form the progression is CLEAR, APPROACH, STOP. A Clear signal indicates that the TWO track segments beyond the signal have no trains or cars on the track. A Approach signal indicates that the track segment beyond the signal has no train or car, however, the second track segment beyond the Approach signal DOES contain a train or cars. A Stop or Red signal can have two meanings - if the signal mast contains a number plate (normally the milepost is indicated) it is considered a intermediate signals the signal indication is 'Restricted Proceed' pass the signal at Restricted Speed looking for a train or other obstruction ahead. If the Red signal does not have a number plate, it is considered an Absolute Signal - to pass the signal the train crew must contact the Train Dispater (or Control Operator) to get specific authority to pass the signal and specific actions they must take in order to pass the signal (line switch positions, leaving switches on or off power). If the Train Dispatcher cannot be contacted for authority to pass the Absolute Stop signal - the train will stay at that location until they can get such authority or the signal lines and displays an indication that will permit the train to pass the signal.
Never too old to have a happy childhood!
Perry Babin Are the signal lights turned off to extend the lamp life or does it have some other significance? In the following clip, there are lights on the outsides of the double track. When the train triggers the lights, both sets switch on. The one on the right has an orange light which would mean to go slow. Is this for a train that would be on the right-side track? https://youtu.be/GVVYFLQESZs?t=60 If so, why would the train on the right-side track have a speed restriction? The answers here helped me use better search terms which led me to the following site. http://www.mikeroque.com/railroad-signals/
Yes, the signal you see is for the right hand track.
Absent more info we do not know why the yellow is displayed on the top head.
Mac
PNWRMNMAbsent more info we do not know why the yellow is displayed on the top head. Mac
Usually, a 2-headed automatic (intermediate) is the signal that comes before an interlocking - sometimes referred to as a "distant signal". So you have there an approach signal, which means: proceed, prepared to stop at the next signal.
It's been fun. But it isn't much fun anymore. Signing off for now.
The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.t fun any
Perry Babin Is there a definitive guide for the signal lights for US railroads? I've found a lot for Canada and Europe but nothing that's consistent for US railroads.
You are posting this on the Trains forum, so I will assume you are intersted in current practice.
But current practice in the US is the outgrowth over 100 Class I railroads who 50-70 years ago each had their own signal systems - all similar concept but sometimes very different in how they appeared and worked.
Because replacement is costly, many of these old systems are still in place, or are just recently being upgraded and standardized.
And because the current major carriers are the product of dozens of railroads being consolidated into one, multiple different signal systems still exist within each of these large carriers today.
So there is no "one" definitive guide........
Sheldon
zugmannUsually, a 2-headed automatic (intermediate) is the signal that comes before an interlocking - sometimes referred to as a "distant signal". So you have there an approach signal, which means: proceed, prepared to stop at the next signal.
But when did they start allowing interlocking approach signals to be approach-lit? I thought if there was gospel in wayside signaling, it would be that distant and home signals were Always On.
OvermodBut when did they start allowing interlocking approach signals to be approach-lit? I thought if there was gospel in wayside signaling, it would be that distant and home signals were Always On.
I've known home signals that were approach lit, as well. So, [shrugs].
Is kind of cool to pull up and see like 6 signal heads all light up at once. It's like a magic trick: "taa-daa - stop signal!"
Full disclaimer, I'm just guessing that's a distant signal. Maybe it's just a 2-headed automatic.
zugmann Overmod But when did they start allowing interlocking approach signals to be approach-lit? I thought if there was gospel in wayside signaling, it would be that distant and home signals were Always On. I've known home signals that were approach lit, as well. So, [shrugs]. Is kind of cool to pull up and see like 6 signal heads all light up at once. It's like a magic trick: "taa-daa - stop signal!" Full disclaimer, I'm just guessing that's a distant signal. Maybe it's just a 2-headed automatic.
Overmod But when did they start allowing interlocking approach signals to be approach-lit? I thought if there was gospel in wayside signaling, it would be that distant and home signals were Always On.
When CSX's Old Main Line subdivision had the former B&O CPL signals, the signals on the line were constant lit. When the subdivision was resignaled for PTC operations with the ubiquitous 'Darth Vader' signals, the subdivision was changed to approach lit. This includes the Absolute signals at Control Points.
The interlocking (control point) I drive past regularly is always lit--Richmond, CA on the UP. Near Albany.
I've seen plenty of ABS signals on the same side of the track, these days. I have an impression I saw an example of such a thing back with searchlight signals. Does anyone recall such a thing. I believe one was placed on the wrong side of the track because of a curve and various obstructions.
It IS possible I'm misremembering. But it's been stuck in my head for awhile, now.
Just wondering if it's true or I made it up.
Ed
7j43kI've seen plenty of ABS signals on the same side of the track, these days. I have an impression I saw an example of such a thing back with searchlight signals. Does anyone recall such a thing. I believe one was placed on the wrong side of the track because of a curve and various obstructions.
As I recall, the signal for the #1 track for eastbound at East Deshler is on the left side of the track. The cantilever there has the signals for #2 track eastbound and the SE wye/transfer.
Again at Deshler, the southbound CPL at Reservoir, just south of the diamond, is on the left side of the track because of how the SW wye/transfer comes in to the Toledo (N-S) line.
CPLs are fun - a full CPL will have not only the center disc, but six "markers," three above and three below, and the disk will include a lunar aspect as well. At any given location, though, only the "markers" that are needed for that location will be installed.
For example (again at Deshler - one of the last outposts of CPLs), the signal governing the point where the SE wye/transfer enters the Toledo sub only has one marker, at center below the main disc. This indicates slow speed. Since the wyes are 10 MPH, you'll never see anything faster.
7j43kThe interlocking (control point) I drive past regularly is always lit--Richmond, CA on the UP. Near Albany. I've seen plenty of ABS signals on the same side of the track, these days. I have an impression I saw an example of such a thing back with searchlight signals. Does anyone recall such a thing. I believe one was placed on the wrong side of the track because of a curve and various obstructions. It IS possible I'm misremembering. But it's been stuck in my head for awhile, now. Just wondering if it's true or I made it up. Ed
Different carriers have different standards on Approach Lit or Constant Lit.
Remember, most of the legacy signal system standards and installations in the modern era were actually created when steam engines were still operating in revenue service, when many carriers operated their GP7's and 9's long hood forward. In those cases it would be virtually impossible for an Engineer to have a CLEAR VIEW of a signal placed on the left side of the tracks in the direction of motion except at a far distance. Today, in the 21st Century, very few engines get operated long hood forward - at least on through freights. Some Local Freights or Road Switchers operating in round trip manner will have to operate long hoot forward in one direction if they only have a single unit. When I was working, most Locals or Road Switchers were powered with a Mother-Slug and thus had a short hood leader in both directions.
When I first moved to Memphis the ex-Southern NS line still had the 'legacy' three-aspect heads. This was non-approach-lit, restrictive red rather than permissive green like Patenall's approach (block signals between sidings were green, and the relay logic displayed green in the opposite direction when a train had just passed). At each block there were signals on opposite sides of the track for opposite directions.
This was rebuilt in the PTC era to UP-style 'Darth Vader' signals, which are usually paired back-to-back with one set of equipment cabinets, on a common foundation on one side of the track.
Overmod zugmann Usually, a 2-headed automatic (intermediate) is the signal that comes before an interlocking - sometimes referred to as a "distant signal". So you have there an approach signal, which means: proceed, prepared to stop at the next signal. [Puts up hand respectfully...] But when did they start allowing interlocking approach signals to be approach-lit? I thought if there was gospel in wayside signaling, it would be that distant and home signals were Always On.
zugmann Usually, a 2-headed automatic (intermediate) is the signal that comes before an interlocking - sometimes referred to as a "distant signal". So you have there an approach signal, which means: proceed, prepared to stop at the next signal.
[Puts up hand respectfully...]
It's been mix-n-matched situation over the 40+ years that I have been a railfan, even on different subdivisions/districts of the same railroad. I can only presume that the signalling systems on the various lines across the country were designed to meet the specs that were in vogue on each railroad at the time they were either installed or upgraded. I believe, however, that almost every interlocking in the country is designed to automatically go into approach lit mode if the commercial power fails.
Up until PTC was installed thru Springfield, IL on NS' Decatur-KC line, the Illinois & Midland/NS interlocking was protected by continuously lit signals on the IMRR side and approach lit signals on the NS side. What made this arrangement even more unusual was that every other interlocking and intermediate signal on the entire NS Springfield-Hannibal District was continuously lit before the PTC cutover. This interlocking plant is maintained and controlled by the IMRR. The only explanation that I have ever come up with is that IMRR (and before that the C&IM) didn't want to spend any extra money replacing bulbs in the NS signals. At various times in the past they also couldn't be troubled to line NS trains thru town either. NS tried to use the PTC mandate to take over control of the interlocking, but to no avail.
tree68 7j43k I've seen plenty of ABS signals on the same side of the track, these days. I have an impression I saw an example of such a thing back with searchlight signals. Does anyone recall such a thing. I believe one was placed on the wrong side of the track because of a curve and various obstructions. As I recall, the signal for the #1 track for eastbound at East Deshler is on the left side of the track. The cantilever there has the signals for #2 track eastbound and the SE wye/transfer. Again at Deshler, the southbound CPL at Reservoir, just south of the diamond, is on the left side of the track because of how the SW wye/transfer comes in to the Toledo (N-S) line. CPLs are fun - a full CPL will have not only the center disc, but six "markers," three above and three below, and the disk will include a lunar aspect as well. At any given location, though, only the "markers" that are needed for that location will be installed. For example (again at Deshler - one of the last outposts of CPLs), the signal governing the point where the SE wye/transfer enters the Toledo sub only has one marker, at center below the main disc. This indicates slow speed. Since the wyes are 10 MPH, you'll never see anything faster.
7j43k I've seen plenty of ABS signals on the same side of the track, these days. I have an impression I saw an example of such a thing back with searchlight signals. Does anyone recall such a thing. I believe one was placed on the wrong side of the track because of a curve and various obstructions.
You are correct. And before anyone has an aneurysm, I took this photo from a sidewalk that crosses the tracks. And, no, I didn't dawdle taking the shot.
ns145You are correct. And before anyone has an aneurysm, I took this photo from a sidewalk that crosses the tracks.
Thanks. You could have been standing on either of the streets there - I'm fairly familiar with Deshler, having been there a few times.
Nice illustration of a "high green", too.
You can see these from the PTZ camera when it's pointed that way, at least until the leaves come in, which will be soon.
For the incandescent signals that have 3 possible colors, do they have 3 different colored bulbs behind the lens?
I might add that the Dispatchers model board display only shows if a signal has been lined - it does not show what indication the signal is displaying.
Perry Babin For the incandescent signals that have 3 possible colors, do they have 3 different colored bulbs behind the lens?
One bulb and three coloured lenses on a plate that swings back and forth. Red is in the centre so that if the control mechanism loses power it will go back to red from gravity alone, same idea as semaphores having the down (horizontal) position indicating stop.
This also means that as the signal changes from yellow to green or vice-versa you will see red for a brief moment.
We need a bit more detail here. The 'incandescent bulb' (and then LED) signals with three colored aspects, like for example the UP Darth Vader heads, indeed have three separate bulbs or diode arrays.
A typical semaphore spectacle has three colored lenses, with a bulb and reflector arrangement behind them. Ideally this hangs by gravity if motor power goes out, and the red light is arranged to be on with the blade as far down as it goes... what happens if the motor power also keeps the light lit is less often mentioned.
The signals like searchlight types have an interesting arrangement. These have very powerful condensing optics inside that focus the light very tightly through the area where the colored lenses are -- these are very small, and much thicker than colored glass lenses in ordinary practice. Red, for example, can almost look black when you're holding the thing. Operation of these is as Dude said, in a motorized frame, with red being the intermediate position during a change.
Of course, one consequence of PTC is that any signals that rely on a motorized or active system to choose aspects are deprecated or forbidden, which is why the searchlights are going en masse and I believe the B&O style CPLs are coming up for progressive replacement... may it take decades more! Same is true of any signal that can lose all aspects should a single bulb or element burn out... but less from a PTC than a PSR perspective.
Overmod We need a bit more detail here. The 'incandescent bulb' (and then LED) signals with three colored aspects, like for example the UP Darth Vader heads, indeed have three separate bulbs or diode arrays. A typical semaphore spectacle has three colored lenses, with a bulb and reflector arrangement behind them. Ideally this hangs by gravity if motor power goes out, and the red light is arranged to be on with the blade as far down as it goes... what happens if the motor power also keeps the light lit is less often mentioned. The signals like searchlight types have an interesting arrangement. These have very powerful condensing optics inside that focus the light very tightly through the area where the colored lenses are -- these are very small, and much thicker than colored glass lenses in ordinary practice. Red, for example, can almost look black when you're holding the thing. Operation of these is as Dude said, in a motorized frame, with red being the intermediate position during a change. Of course, one consequence of PTC is that any signals that rely on a motorized or active system to choose aspects are deprecated or forbidden, which is why the searchlights are going en masse and I believe the B&O style CPLs are coming up for progressive replacement... may it take decades more! Same is true of any signal that can lose all aspects should a single bulb or element burn out... but less from a PTC than a PSR perspective.
I thought the search lights had to go away with PTC. That's not been the case. We still have them at a few locations. When the signals get upgraded, they do get replaced with the three light types. I don't believe there's any time requirement for replacement.
The colored vane on the search light type can stick. I've seen it happen. That's why they are no longer favored.
On modern signals, if an aspect burns out, the signal defaults to the next less favorable aspect. A signal with a burnt out green will display a flashing yellow (or yellow if not equipped to flash), etc. I've seen a burnt out yellow aspect display a flashing red. A dark signal head, unless allowed in the signal chart, means the most restrictive indication possible. That doesn't always mean stop for a particular signal.
The old 3 light type had a plain incandescent bulb behind a colored lens. I've came across a signal with the lens broken out. The bulb was a washed out yellow. Looked like an approach indication. Until we got a few cars from it and could see the lens was gone and we were seeing the bulb.
Jeff
Most, if not all, rule books have a rule stating that a Imperfectly Displayed Indication, when seen is to be acted upon as the MOST RESTRICTIVE Indication that that signal is capable of displaying. ie. STOP for an Absolute Signal and Restricted Proceed for a intermediate signal with a number plate.
jeffhergert I thought the search lights had to go away with PTC.
I thought the search lights had to go away with PTC.
I thought that was the case as well, but there may be some grace in non-passenger areas.
There are several still standing guard at Santa Fe Jct. in KCMO.
rdamon jeffhergert I thought the search lights had to go away with PTC. There are several still standing guard at Santa Fe Jct. in KCMO.
Last time I heard anything about the CPLs at Deshler, they were staying until they broke. Many of the signals at Deshler are Darth Vaders already, especially on the E-W line.
IMHO, CPLs could easily be changed over to LED - just a matter of replacing the bulb/reflector/lens assembly. There are no moving parts on the signal itself.
tree68 rdamon jeffhergert I thought the search lights had to go away with PTC. There are several still standing guard at Santa Fe Jct. in KCMO. Last time I heard anything about the CPLs at Deshler, they were staying until they broke. Many of the signals at Deshler are Darth Vaders already, especially on the E-W line. IMHO, CPLs could easily be changed over to LED - just a matter of replacing the bulb/reflector/lens assembly. There are no moving parts on the signal itself.
There are also several safety improvements for fall protection with the new masts. I assume a OSHA mandate.
SD70Dude One bulb and three coloured lenses on a plate that swings back and forth. Red is in the centre so that if the control mechanism loses power it will go back to red from gravity alone, same idea as semaphores having the down (horizontal) position indicating stop. This also means that as the signal changes from yellow to green or vice-versa you will see red for a brief moment.
tree68 and others,
Thanks for the insights. They are informative.
Rio Grande Valley, CFI,CFII
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