Western Railroad Discussion > Lunar Aspect

Can someone explain for me what a "lunar aspect" is? Red, yellow, green and dark is not a problem, but I don't understand lunar. In the Altamont Timetable handbook it looks like a "blue" indication, but I've never seen that. Thanks.

.Lunar is basically a white signal...indicates that you can go by it a restricted speed looking out for lots of things.,

A lunar is a white light when displaced alone or with only solid red lights its a restricting indication and the train may pass signal without stopping at restricted speed(in some cases not to exceed 15 MPH)

If this white light is shown below a yellow light (with or with out a solid res light under it) you are look at an approach restricting. Basically tell the train crew that their next signal will be a restricting. There is no requirement to pass an approach restricting at restricted speed and in in most cases there is no speed restriction associated with an approach restricting.

those the only two lunars I've ever worked with but I've only been doing this for 3 yrs on the west coast and AK so if there are other Signals that include the use of a lunar I would be interested to learn something

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CO097 Wrote:
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> Can someone explain for me what a "lunar aspect"
> is? Red, yellow, green and dark is not a problem,
> but I don't understand lunar. In the Altamont
> Timetable handbook it looks like a "blue"
> indication, but I've never seen that. Thanks.

Answering the part of your question about blue, the color was originally called Lunar White and has been shortened to Lunar. It is ,as Amtkrd4man replied, basically a white light. The white light has a slight blue tint to distinguish it from a white light caused by a broken signal lens, hence the name Lunar.

TAW

It is sometimes an indication to proceed into unsignaled track. Sidings which are not bonded have a lunar signal telling you to proceed at restricted speed. A lunar signal can tell you the branch or alternate mainline is unsignalled with a lunar signal buy you may proceed at track speed beyond the lunar.

And on some CSX territories, a lunar white below one or two reds simply means Restricting.

The "lunar" white is a reference to the bluish white one observes from moonlight. It's arguably a purer white than incandescent white, which is actually slightly yellow.

Note also that some people refer to the marker or pilot lights on B&O style CPL signals as "lunars". They are wrong. The light on these signal heads is standard incandescent white (or, in a couple of positions, yellow).



Edited 1 time(s). Last edit at 08/10/10 11:49 by toledopatch.

Also, if you've ever seen the inside of a signal head that displays a lunar aspect, the lens is tinted blue.

Like so:
http://www.rrsignalpix.com/projects/100_5147.jpg

Pump

fbe Wrote:
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> It is sometimes an indication to proceed into
> unsignaled track. Sidings which are not bonded
> have a lunar signal telling you to proceed at
> restricted speed.


With some exceptions - On the Old Western Pacific (now UP) in California you'll get a Red over Lunar when a train takes the siding. I've also seen this in Eastern Nevada.

Here's a red-over-lunar indication at East Cashmere on the BNSF's Scenic Subdivision in Washington State. The siding here is unbonded, so the lunar indication indicates the train has authority to take the siding operating at restricted speed.

And here's the same signal indication at West Cashmere.

The easiest way to describe the color of a lunar indication is that it is more of a "pure" white than a regular incandescent bulb. The light blue filter element in the searchlight signal mechanism provides this pure white color when placed in front of the lamp. Three-light signals use a blue lens to accomplish the same thing.

-Rick

Rick Selby
Redmond, WA
Pacific Northwest RPM



Edited 1 time(s). Last edit at 08/10/10 12:25 by RAS.

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toledopatch Wrote:
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> Note also that some people refer to the marker

[correct term]

>or pilot

[railfan term]

>lights on B&O style CPL signals as "lunars".
> They are wrong. The light on these signal heads is
> standard incandescent white (or, in a couple of
> positions, yellow).

TAW

fbe Wrote:
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> A lunar signal can tell you the
> branch or alternate mainline is unsignalled with a
> lunar signal buy you may proceed at track speed
> beyond the lunar.

Never seen this application. Most definitely you could get a restricting on to nonsignaled auxilary tracks(e.i. branchline, industrial lead, yard, etc.) but as far as going from signaled to nonsignaled main track I can't say I've ever seen is or see where or why it would be practical. Any time I've ever gone from signaled track(ABS or CTC) to non signaled TWC or DTC that is clear or trains, engines, railroad cars, and all switches are lined main to main all the way to the end of the signal circuit(boned track) the last signal should display a clear indication. If for some reason the dispatcher has to flag you by the last signal or the ABS signal shows stop and proceed there is a sign usually a mile or two into the nonsignaled territory that says "end of block" at that point what ever signal you came in on no longer applies and you are solely operating on your track authority.

Yes the red over lunar on the original WP was because the sidings were not bonded and therefore one could not tell if the siding was occupied. Hence, rather than giving a red indication requiring contacting the dispatcher to obtain permission to go by absolute signal displaying red, the lunar indication allowed you to go by at restricted speed (or less if the turnout speed required a lower speed) with the usual restrictions of being able to stop within 1/2 the range of vision etc....

Lunar was truly "VFR" aka visual flight rules, in most cases you'd
be barely over walking speed and as been stated especially on the WP
it took care of the problem of having to bond sidings in areas where
water and ground conductivity caused constant signal problems.

IRRC A lunar signal on the Rock Island ment "Proceed prepared to stop short of train, broken rail, switch not properly lined, or diverging route at speed not exceeding 10 mph".
I may not have it word for word but that was the gist of it. Dan Tracy

"Nor exceeding 10 mph" pretty standard boiler plate.

rehunn Wrote:
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> "Nor exceeding 10 mph" pretty standard boiler
> plate.
Restricted speed on BNSF = 20 mph prepared to stop within half the range of vision short of equipment, men, switch, derail, et al.

The location in this image is the Black Butte Yard on the UP Black Butte Subdivision (CA).

The first view is looking south (towards Dunsmuir). The train is a CORP local exchanging loads and empties between Black Butte and Weed. In the photo the train is making a reverse move southward on the siding toward the crossover. The movement is into a red over red over lunar.

Passing the crossover, the train will move onto a pair of spurs that are not part of the CTC system, using hand throw switches. On the other side of the crossover is a similar signal mast for northward movement. When the train leaves the siding and is fully on the spur track, the signals drops to dark (second image). Returning from the south spur northward, the train picks up the northward lunar in the third image as it re-enters the siding.

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frcanyonsub Wrote:
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> The location in this image is the Black Butte Yard
> on the UP Black Butte Subdivision (CA).
>
> The first view is looking south (towards
> Dunsmuir). The train is a CORP local exchanging
> loads and empties between Black Butte and Weed. In
> the photo the train is making a reverse move
> southward on the siding toward the crossover. The
> movement is into a red over red over lunar.

And in the first view, the mainline absolute signal is green, suggesting a southbound UP train has been granted a route through Black Butte to proceed toward Dunsmuir!

I'll try to get this right but I'm no maintainer....will stand corrected as necessary! On the D&RGW lunars were used on ABS intermediates between CTC control points to permit following trains to enter an occupied block behind train ahead operating in the same direction, at restricted speed prepared to stop. The lunar illuminated only if the following train had actually entered the preceeding block (on a solid yellow). In other words if you were standing there watching a train passing the intermediate it would drop to red only, it would go dark as soon as the train passed, and stay dark unless another train entered the block before the train ahead exited the protected block, at which time the red over lunar would illuminate. The basic effect was as an illuminated "G" plate. I assume it was also somewhat more "fail-safe" than a plate alone in that I assume the lunar would not illuminate if the train in the block ahead was actually coming toward the train seeing the lunar, but I don't know that for certain, since lining a train east out of Silt (in this case) against a train west out of New Castle should have been impossible in the first place. Although I guess that begs the question: what if there was a maintenance situation requiring pieces of equipment big enough to activate signals, one lined and signaled out of East Silt and the other talked out of West New Castle -- would the first intermediate east of East Silt indicate red over dark, or red over lunar? That one's way outta my league!

I don't know if UP still recognizes this function, but I know that at least as recently as last spring the first intermediate east of Silt was still so equipped and the lunar illuminated when a track test car following a slow-moving eastbound coal load entered the main from East Silt.

lowwater

Thanks to everyone who answered my quesion about what a lunar aspect was. The answers were great...and know I know! :)