Where can I find out what the different signal aspects mean? For example, orange over red, green over orange, etc.
Welcome to the Forum! I would start with looking through a couple of threads about signals that have been on this very Forum within the past two weeks. I think one of them connected to an informative web site that tells about signal aspects and indications. Try http://www.alkrug.vcn.com/rrfacts/signals/signals.htm
A warning: not all of his information is 100 percent accurate in all cases, but it’s certainly a good place to start. Second, I should point out that signal aspects mean different things on different railroads, so a lot depends on what railroad you’re observing.
And finally, what you’re calling “orange” is really amber, and is usually referred to as “yellow” in signal aspects, or at least here in these parts!
In the first case, a yellow-over-red almost always means “proceed preparing to stop before any part of train or engine passes the next signal”.
Green-over-yellow? Probably indicates a malfunction, as I cannot find that signal in the rules of any major railroad![;)]
Careful what you ask for!
As Carl pointed out, different railroads assign different meanings to wayside signals.
Aspect means what the signal is displaying…colored lights or lights in a particular position or a combination of both
Indication is just that, the signal is indicating what you should, or should not do, such as stop, or proceed to the next signal prepared to stop, proceed at a given speed, so forth and so on.
There are 2 basic signal aspect systems in use, you can find them in the two major rule books in use here in the USA…those rule books are Norac, and the GCOR.
For the most part, Norac, rules apply east of the Mississippi river, and convey things think track speed and and such.
http://en.wikipedia.org/wiki/Northeast_Operating_Rules_Advisory_Committee
West of the Mississippi, GCOR rules are dominate, and signals generally indicate permission to occupy a particular section of track…
http://www.trainweb.com/gcor/index.html
For the most part, what a signal means, what it allows you to do or prevents you from doing is contained in the general instructions and timetable of each individual railroad…
Was there a particular signal at a given location you had a question about?
Carl, I remember seeing, possibly in the 1943 SoRy rule book I have, but has wandered off somewhere, green-over-red, with the indication of Proceed. I inferred that if the top aspect is green, the lower head(s) were of no force, but I may be wrong. If green-over-red is a proper aspect, the engineer indeed should indeed stop if he sees an aspect, such as green-over-yellow, which is not listed in the signal rules, and learn just what the situation in the next block is.
I have had the impression (possibly wrong) that a less-restricting aspect is beneath a more-restricting aspect, the more-restricting aspect is modified: yellow-under-red is less restricting that red; Green-under-red is less restricting than red and also less restricting than yellow-under-red, and green-under-yellow is less restricting that yellow.
Correct me if I am wrong.
Johnny
Green over Yellow? Actually in the 1956 edition of the New York Central Rules of the Operating Department there is a green over yellow aspect: Rule 281 A; Name: Advance Approach Medium; Indication: Proceed approaching second signal at medium speed. I suspect it was used to increase stopping distances where signals spacing was short. Also, if I remember right, there was a bad passenger train wreck in New York State in the 1940s. A train went around a 30-40 MPH curve at 70-80 MPH and derailed with significant loss of life. I think the green over yellow aspect was used (with automatic train stop inductor) to warn of the curve. However the train did not reduce speed.
Johnny, I think you basically have the right idea.
There is also the rule that a signal improperly displayed (green-over-yellow, for instance) or the absence of a signal where one is normally displayed, should be regarded as a stop signal.
Now, as for green-over-yellow, it probably has been changed since those NYC days (or it may still be used in places other than around here–I was going by my CORA book). But one of the rules governing signal system design is that if a signal head should go out, it would be assumed to be red, and you would be governed by the most restrictive indication that the signal could display. If the yellow light on that green-over-yellow went out, you’d be seeing a clear signal, which would be fine until you got to the second signal and did not have enough time to react.
Clarkfork, I don’t think signals would be used to slow a train down for a curve. That would be done with a permanent speed restriction in the timetable, with general orders or bulletins providing exceptions for specific trains if necessary.
Gulf Curve at Little Falls, NY.
The engineer hit the curve too fast, then closed the throttle, causing the train to push the tender and engine off the track with the rest of the train piling in. It’s been opined that had the engineer kept power on they probably would have made the curve.
Nothing in the book about the accident mentions any signals, IIRC. It was a timetable slow order, as Carl suggests.
In a unrelated note, the NYC rebuilt the curve, largely as a result of the accident, moving part of the Mohawk River in the process. You can easily see the old alignment, and that the river has been relocated, in any satellite photo.
In the current NORAC books, the only green over anything is Green over Red. Anything else is a malfunction. Although some dwarf signals display green over green for clear.
NORAC defines green on top as a clear.
Nick
Not to play “Gotcha !” with my good friends here - because most of this still baffles me, as I’m convinced they’re all randomly different [swg] , and I didn’t have to look too hard among my ‘Favorites’ websites for signal matters - so I’ll just point out that this website and page, by Carsten S. Lundsten:
Railroad Rules, Signaling, Operations:# Signal Aspects and Indications# Bessemer & Lake Erie, 1957Created 18-01-2002
Source: Bessemer & Lake Erie Railroad Operating Rules
"Based on my own observations along B&LE in 1999/2000, the Signal Aspects and Indications as presented below are still va
Below is a portion from the ICC Accident Report for the Little Falls Accident of 4/19/40: This is the only time that I have heard of block signals used to enforce a curve speed restriction. ATSF did and BNSF still does (I think) use inert ATS inductors to enforce speed signs in a few situations. A missing inductor protecting a curve speed restriction was involved in an Amtrak/ATSF accident on the Topeka line in the 1970s.
(I remembered all that, now where did I put the car keys?)
“Signal Engineer Elsworth stated that the most favorable aspect displayed by signals Nos. 21421 and 21531 is green-over-yellow, which requires that an engineman forestall to prevent an automatic train-stop brake application. The purpose of this indication is to insure that an engineman is alert when approaching Gulf Curve; however, should an engineman be incapacitated or lost as to location, an automatic train-stop brake application would stop the train before it entered the curve.”
Every signal circuit I have touched for a multiple-head location has a light-out (LO) circuit that will give you a more restrictive indication than what you might have got with a single head lit, if the single head lit paired with a dark signal could be interpreted (especially from a distance) to give a more favorable indication than the combination of the two.
For example, at a location that was supposed to give you a red over green, and the red burned out in the upper head, the LO circuit will give you instead a red or yellow in the lower head, depending on which is needed for safety. At the same location if the red burned, out you have not gained a more favorable indication with a green over dark, but even so, depending upon railroad’s practices, you still might get
[(-D] [snip; emphasis added - PDN]
Cue the ‘‘Twilight Zone’’ music, man . . . [:O]
Well, that is indeed a good use of Automatic Train Stop, with a signal displaying an innocuous indication just to require the engineer to forestall. I will submit, however, that it didn’t work in this case. The engineer evidently forestalled the ATS application, but then continued on at maximum speed, thereby defeating the intent, if not the letter, of the signal.
RWM, that safety feature is something I hadn’t known about before–thanks!
I’ve got to teach a CPR class tonight, but if I remember, I’ll pull out the book when I get home. From what I recall, it was reported that the engineer apparently did not make a brake application as he no doubt should have. Instead, he closed the throttle. IIRC, it was noted by someone (the fireman or another crew member in the cab) that the look on his face was essentially “I know I just screwed up royally.”
The engineer survived the crash, but succumbed to his injuries before he could be extricated from the cab. He never told his side of the story.
I was watching NS in Atlanta GA near Inman Yard.
Almost every employee timetable I have seen has, in its Special Instructions (or similar section), a list of the speed restrictions on each line shown in the TT. Not only are there speed reduction signs (some showing different maximums for freight and passenger) before curves, and over bridges and structures that cannot be traversed safely at track speed, there are also fixed signs (usually, RS) at the end of the restricted area, indicating that it is safe to resume trackspeed. I have a RI TT (Des Moines-Minneapolis) that lists “speed zones,” and there were lineside signs indicating the beginning of each zone.
Johnny