Western Railroad Discussion > what is lunar?

In a couple messages back, you were talking about signals, and with at you guys were talking about the combination of different colors. There was one message that said, yellow/red/lunar. I get almost everything but what is lunar. What happened to good-old-fashion green?

Hi santafeandrew-

The "lunar" condition generally refers to some type of restricting aspect. A lunar signal is supposed to be a bluish-white in color, although many signal really just look white.

The attached image is an example of a lunar signal. This signal is "lunar over red" which is restricting. This particular signal is at Prospect Jct in Denver.

Hope this helps!

Kevin
http://www.drgw.ws

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The name for lunar white refers to that slightly bluish-white color you get reflecting off the moon on a clear night. I suspect the reason for that specification is so that it is distinct from incadescent lights that may be near the tracks, and aren't really a true white either.

I have a lunar lens, and it looks like a dark sky blue. But held up to a light, it's a very pure white, not incandescent yellow-white. Helps to distinguish from a shot-out lens which a clear lens might otherwise convey.
~GP-38

In railroad terms. Lunar=restricting. Restricted speed. When a train or engine is required to move at restricted speed all movements must be made at a speed that allows stopping whithin half the range of vision of train, engines, railroad cars, men and equipment fouling the track, stop signs and derails... Keeping an eye out for broken broken rail and all that other happy horse ****. Basically go slow and don't hit or kill anything. If you do... It's your fault, you were working on a Lunar. It really doesn't matter what the exact definition of the color it is.

Is it easy to mistake a lunar indication for a yellow indication?

Maybe a real railroader who has looked at them both, can answer better, but from a theoretical viewpoint no, you can't confuse lunar and yellow. The bluish lunar lens should filter out most of the yellow.

--George

Confuse the two? Not unless your glasses are really dirty :) It is somewhat similar to the difference in color between the light generated by an incandescent bulb and a florescent tube.

Amber or yellow is a very distinct color, totally different visually from green, lunar white or red. Prior to work done by Corning Glassworks in the early part of the twentieth century, there was no practical way to produce a yellow or amber color without a red or green tint, however slight.

Because of this fact, railroads refused to use yellow for signal indications as a general rule. Thus the old signal standards used white for the clear indication, green for caution and red for stop or restricting. Once Corning perfected the amber colored lens, that freed up the green and white colors to be used for other indications and made the signalling system totally fail-safe in that if a roundel (proper name for the colored glass lens) was broken or fell out, the train would have to consider the signal improperly displayed and follow the appropriate operating rules.

Lunar can be hard to differentiate on some older signals. I've seen some on the SP that almost look green (scary). But knowing that a particular signal can display a lunar aspect, you know to look for it. They have a new signal where I work that displays lunar and it's very distictive. Looks nothing like green or yellow.

However I did have a hoghead who mistook it for green one time. Again, knowing where you are and what to look for. He notched back off when I said "better look again!" after he called "yellow over green". That instance was just a case of what you usually see versus what is new.

Most RRs, or at least mine, are using more flashing red these days, because it means the same thing. The only exception is Yellow over Lunar, which is "Approach Restricting". For some reason they won't create a Yellow over Flashing Red aspect for that indication.

Happy Holidays

I guess it must be different around here (Ohio) where I see plenty of yellow, green and red signals on the WLE and NS, I guess I never noticed a lunar. The yellow is a very distinctive yellow not to mistaken for any other color.

Thanks for the comments, guys!