Marker lights on a caboose......

[oldline1]

The Western Maryland Ry used red to the rear and amber/yellow in the other positions. The markers were able to be repositioned when in a passing siding to show amber/yellow to the rear rather than the red used when running or stopped on the mainline.

oldline1

[BigJim]

The N&W only used yellow and red on cab markers. 

[cv_acr]

This is the full rules for end-of-train markers from the 1962 Canadian UCOR, I expect it was the same or similar on all or most US railways as well (except for examples cited above like ATSF using amber instead of green).

19. MARKERS – the following signals will be displayed to the rear of every train to indicate the rear of the train.

1. By day – markers not lighted.
2. By Night:On single track and when running with the current of traffic on two tracks, markers lighted displaying red to the rear.On two tracks, when standing or running against current of traffic, markers lighted displaying red to the rear on the outside, and green to the rear on the inside.

   On more than two tracks, when running with the current of traffic, or when standing or running against the current of traffic, markers lighted displaying red to the rear unless otherwise directed by special instructions.

   When a train is clear of the main track to be passed by another train, lighted markers will display green to the rear.

When the rear of a train is equipped with built-in markers, they must be lighted by day and by night.

When a train is equipped to display a single flashing type marker it will be unlighted by day; by night it will display flashing red to the rear, except when clear of the main track to be passed by another train it will display flashing green to the rear.

EXCEPTION: The requirement that markers display green to the rear when clear of main track does not apply in CTC.

[SD70Dude]

In addition to what has already been said, when stopped on double track or running the 'wrong way'  (against the current of traffic) on double track the inside rear marker was green, while the outside was red.  

[PATRICK A FLORY]

The Santa Fe used amber instead of green.

[Anonymous]

I have seen BN cabooses with only the one large round red light that was mounted on the very back of the caboose. I have seen UP cabooses that had a box (somewhat like a traffic signal) that had both red and green lights in it. I know that Frisco used the Adlake markers (2 of them one on each side of the caboose) and they had red, green, and maybe yellow. I am not sure about yellow but the red was to the read and green showed to the side.

[Anonymous]

Operating rules dictate colors of marker lights and how they are to be displayed. Note that the rules are subjcet to variation from one railroad to another, and that the rules have changed over the years. In most standardized rule books, Rule 19 will govern markers.

The most common application calls for red to be displayed to the rear of the train, and green to be shown to the side and front. The Santa Fe and some other railroads called for red to be shown to the rear, and yellow to be shown to the side and front.

The rules have changed over time as to conditions under which a color other than red was to be displayed to the rear. Since it isn't practicable to "turn" or change colors on model marker lamps, I'd go with red to the rear and, depending on your prototype, either green for the other 2 lenses, or yellow for the other 2.

John

[cacole]

Back in the days when caboose marker lights were removable kerosene lanterns, there were only two colors, red or green. Red faced the rear when the caboose was on a main line to protect the train from being rear-ended. Green faced the rear when the caboose was on a passing siding clear of the main line. The conductor or one of the brakemen who rode in the caboose were responsible for turning the lantern to the appropriate color. I don't recall ever seeing a lantern with a yellow lens, at least not in Illinois. A Google search of railroading rules and regulations might turn up an answer for you.

As an added precaution against rear-end collisions, a brakeman always put out a red fussee if the train made an unscheduled stop on the main line, because the kerosene lanterns were not very bright.

[joseph2]

I would guess normally red,so the caboose doesn't get rear-ended by another train.Green when the caboose was on a passing track waiting to be passed.Never heard of amber. Joe G.

[countboese]

When using UTAH PACIFIC Marker Light System which way do the red, green, and amber lights face?