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.
A good reference chart source:
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 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.
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 o
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
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.
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
[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.
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.
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
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.
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.
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
You are correct. And before anyone has an aneurysm, I took this pho
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?