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[Youngrail]

I'm bewildered by some signals I see on the UP.  So on a signal head you usually see three lights as follows:

o - green

o - yellow

o - red

But on the UP I see signal heads with four lights and I have no clue what the other aspect is.  I'm assuming lunar but never seen it lit.  It would be in the pattern of:

o - green

o - yellow

o - (what is this one?)

o - red

Educate me :-)

[ndbprr]

Well nobody has commented and I know nothing about the UP so I can only speculate since the PRR had a similar situation.  The PRR had a light mounted lower on the signal mast that could be lit to allow a train climbing a grade to pass a red signal IF it would stall on the grade otherwise.  There were serious speed restrictions associated with the maneuver and the engineer had to be able to avoid a collision knowing there was another train in the block ahead.  It could be to allow something similar.

[BTP Productions]

I know just what you are talking about and I am unsure also. I do have an idea though, it may be white (also called lunar to some railfans). On former B&O signals it indicated speed restrictions. On modern CSX signals I've seen them being used to indicate a train meet.

If I am wrong on this I would like to be corrected, but I am pretty sure!

[csxengineer98]

I know just what you are talking about and I am unsure also. I do have an idea though, it may be white (also called lunar to some railfans). On former B&O signals it indicated speed restrictions. On modern CSX signals I've seen them being used to indicate a train meet.

If I am wrong on this I would like to be corrected, but I am pretty sure!

it isnt just used by railfans..that color is called lunar white... when used in a traffic like style signal head it shows the indication of restricting.. aka prossed at restricted prossed..

csx engineer 

[4merroad4man]

I run on the UP and have yet to see one.  Show me a photo.....

[csxengineer98]

http://www.alkrug.vcn.com/rrfacts/signals/signals.htm

this might give you alittle info...im trying to find a traffic light style singal pic with the lunar white light..

csx engineer 

 

[Railway Man]

I'm bewildered by some signals I see on the UP.  So on a signal head you usually see three lights as follows:

o - green

o - yellow

o - red

But on the UP I see signal heads with four lights and I have no clue what the other aspect is.  I'm assuming lunar but never seen it lit.  It would be in the pattern of:

o - green

o - yellow

o - (what is this one?)

o - red

Educate me :-)

Not aspect, but light.  The aspect is the totality of what's lit, such as red-over-green, flashing yellow, etc.  The fourth head is usually another yellow light, so the signal can provide a yellow-over-yellow aspect, which is a diverging route indication.

There are hundreds if not thousands of lunar lights on UP.  The most frequent use is the entering signal for a non-bonded siding, where the best possible aspect is red-over-lunar, indicating diverging route, restricted speed.  Many of the sidings on the former Western Pacific and Oregon Short Line are non-bonded.

RWM