Railroad Signals Explained: Part 2

[@artillerest43rdva7]

well done! explanation of a complex topic, in straightforward terms.

[@billmorris2613]

We were using the lunar on the southern end of the UP down here in Louisiana the last time I was out on the main line in 2009. They have recently done some up grades and I’m not sure if the lunar signal has been discontinued or not. I do know it is still used on other railroads in the New Orleans area. UP did do some upgrades to tie in another railroads tracks along with the Huey P. Long Bridge over the Mississippi River just up river from New Orleans, LA, into the UP dispatcher in Spring TX. This begins CTC going to the bridge which terminates at the south entrance to our UP yard and the BNSF ( old SP ) yard. The new CTC now includes the main line or possible both main lines through the UP yard at Avondale and connects with the old CTC at the northern end of our yard limits. I believe they still used a lunar indication at that junction which controls routes to the bridge and to two other railroads. I too like the lunar signal and it was my favorite of the colors used in the signal system. It has a much richer look than any of the other colors. Lunar with a touch of pearls. But for operations, green was my favorite color. The more green / clear signals meant I made my money faster, as we got paid by the mile. I made the same dollar amount for the basic trip between the two terminals rather it took 5 hours or 12 hours.

[@bfurailroad1104]

To see you call out my name and then see you laugh was the best Christmas present I've ever gotten. Thank you Mark! And thank you for dedicating your time and investing many hours of video editing down into just 15 minutes. You've got a lot of knowledge that's fer sure. I've watched this video 3 times and I know a lot more now than I did 45 minutes ago. If you were still a signal man and I were a new hire/trainee, you'd be tryin' to get me transferred somewhere else coz I'd be asking a lot of questions. Getting information from the relay folks around here is like pulling teeth. What I find most interesting is the Approach diverging aspect. Here at the UP yard in Herington, Ks there's 2 mainlines leaving the yard with each mainline having its own signal pole with 2 heads each. I've spent many hours studying these and the top is always red, never changes. The next Cp is one mile away still double track with a double crossover, there's also 2 signal poles with 2 heads each. These top signals will change. The next Cp one mile away the double tracks go to single track. And then to get really confusing, going the other way, entering the yard, there's just one signal head on each pole for each mainline.

[@MarkClayMcGowan]

I'm glad you didn't get annoyed at it! It just struck me funny right then. I don't know why the top heads aren't controlling mainline movement. Perhaps installed for future use. Sorry for the delay in responding!

[@bfurailroad1104]

@@MarkClayMcGowan I think a lot of peeps find my channel name funny. I've been thinkin' about changing it to FNBS freight lines. (Effin bull sh*t, get it?) And no problemo on the response delay, you be a busy guy and I understand how things fall into the crackz.

[@MultiMightyQuinn]

I really like your style and content. Thank you for sharing your piece of the world, much needed right now!

[@charlesgault3777]

There are some railroads who use the lunar white for restricting. CSX, Metra, CN's former Illinois Central mainline. The lower signal head has four lenses instead of three.

[@MarkClayMcGowan]

Sorry for the delay in replying. I was never sure if anyone else used the lunar. Thanks for the info and for checking it out!

[@jovetj]

@@MarkClayMcGowan CSX is all gung-ho about the Lunar White, while UP and BNSF are using it less and less... Older Speed signaling systems don't use Lunar White at all, and instead R/R/Y means Restricting (and sometimes R/Y).

[@eatonbeaver6083]

On the UP here in Vegas i've seen both lunar and flashing red. There is a CP with a spur into an industrial yard and when the train is entering the yard it shows the red over lunar and it has recently converted LED heads. But then i've seen trains taking the siding south of here at Jean and they get yellow over flashing red aspects on the intermediate and at the CP.

[@MarkClayMcGowan]

The lunar and FR signify the same indication. Entering occupied or dark territory. We got rid of all lunars over here some time back but ive heard they still use them in specific signaling.

[@SETX_Sirens_and_Rail_02]

I live along the former SP sunset route in Southeast Texas and I have noticed a green over red signal at a nearby control point. I saw on another video that it's like the red over green but the train is instead lined through the main rather than the siding. Just wanted to confirm that that's how it works with UP. Thanks!

[@MarkClayMcGowan]

The top signal is always for the main line. At SP both signals were always lit so there was no confusion about which signal was which in case of a light out. Some UP signals are that way, some aren't. It just depends on the programming at a location. I hope that answered your question.

[@SETX_Sirens_and_Rail_02]

@@MarkClayMcGowan Thanks! I have passed the control point at the east end of China, TX siding and seen a green over red with a train coming then the train just passes the switch and stays on the main. The signals on both ends of the siding are old SP installs but UP just upgraded to newer LED signals nearby as well us upgrading some crossings.

[@Pasco-Spokane-Railfan-2024]

On the BNSF in Pasco WA you still have some 70's safetran houses and signals all of the signals around here are incandescent

[@MarkClayMcGowan]

The upgrades depended on whether or not PTC would be part of it. If it wasn't the old systems were generally left in place. Last year on my roadtrip to Denver, I saw a bunch of semaphores still active on the BNSF in New Mexico. I understand they have since been replaced with colorlights.

[@itz_mxxri]

Hi, Mark! At a BNSF yard, I saw a flashing green signal, which I've never seen before. What does that mean?

[@MarkClayMcGowan]

UP has a yellow over flashing green and is "approach clear 60" in advance of a 60 mph turnout. I don't know how BNSF uses them or what it would mean by itself.

[@itz_mxxri]

Now that I think about it, I believe there was a yellow over the flashing green. So it must mean the same thing. Thank you for your reply. I've always been interested in the railroad. And I've really enjoyed all your vlogs.

[@nrschum]

Hi, Mark! New subscriber here and really enjoying your videos! I've been watching a webcam (UP in Carroll, IA) that has a pair of intermediate signals in view and notice that it can take anywhere from 10 to 15 seconds after the leading axle crosses the insulated joint to knock down the signal. The timing doesn't seem to be related to train speed, and the front of the train is usually well beyond the signal by the time it shows red. Is there a timing mechanism in the circuitry, something related to the relays, or something else? Thanks in advance!

[@MarkClayMcGowan]

Microprocessor control systems react more slowly than the old relay systems did. If a relay was down, it was down. With the new systems, they have to run checks to confirm the yes or no, and that takes a few seconds. Thanks for checking out the channel!

[@nrschum]

@@MarkClayMcGowan Awesome! Thanks, Mark!

[@markhayes6407]

Thanks for the class. I enjoyed it.

[@MarkClayMcGowan]

Sorry for the delay in responding. I'm glad you found it informative!

[@TexasRailfan2008]

I always enjoy finding searchlights as they are my personal favorite kind, the whole time there has been some in my hometown and I didn’t even know it lol

[@MarkClayMcGowan]

Odd what we find in our own back yards! Thanks for checking it out!

[@TexasRailfan2008]

IKR!

[@michaelsmodelrailroading7665]

Thank you for this and your previous videos, explaining railroad signals. What type of bulbs are used in railroad signals? In some marine applications, such as running lights, double-filament bulbs are used, to reduce hazard of a burned out filament. Have LED signals found their way into railroad signal applications yet?

[@michaelsmodelrailroading7665]

I noticed that you answered my LED question at the end of your video.

[@mikepuccini4932]

Interesting! Mark..I always wondered how they kept trains from apart. Thanks from Ontario Canada

[@MarkClayMcGowan]

You're very welcome! Thanks for the compliment and for checking it out!

[@speedracer3104]

Funny you mentioned lunar. UPRR feather river route has at least one lunar working. I don't go out like I use to because there's no traffic hardly. Any UP traffic is always westbound. Idk what an eastbound looks like, lol

[@ClintStahlerUSA]

Another great video, Mark - thanks for posting!

[@MarkClayMcGowan]

Sorry for the delay in replying. Thanks for the compliment and I hope you have been enjoying them since!

[@michaelmorgan7893]

I like these videos. Even though I'm planning a model train layout based on SP and Santa Fe of the mid to late 70's, I want to have a somewhat simplified signal system. I run all DC on my layouts, so whatever I design will have to remain simplified. However I like the flashing gray white lunars, too. SP had those in those old HC33'S (bean pot looking heads), usually mounted below a dwarf H2 head.

[@MarkClayMcGowan]

We (SP) had an HC33 "S" signal at Summit until the UP took over in 96.

[@chpalmer2007]

Thank you Mark!

[@dougackerman4182]

Really enjoyed this video Mark

[@MFXdump]

Looking at some of the comments, you may want to distinguish between AAR, and NORAC signaling someday. Great video!

[@MarkClayMcGowan]

I got a lot of comments on facebook when I posted this link to some rr groups about the differences not only in regions but on different roads. I hoped someone familiar with other systems might take up the challenge but no one has. As a west coast guy I'm not familiar with NORAC signals. Maybe if I find the time I'll do the research and talk about it but these videos were very time consuming! Thanks for the comment, suggestion and for checking it out !

[@MFXdump]

Mark Clay McGowan I wouldn’t worry about it too much. There are videos already on KZbin that explain it. There are people out there that don’t know there’s a difference though. They might be the same people who think concrete ties make a track “modern”.

[@MarkClayMcGowan]

@@MFXdump haha! Cool. Thanks again for checking it out!

[@billmorris2613]

Good afternoon from SE Louisiana 19 Mar 21.

[@roger8772]

Woo im gonna open up train simulator and play engineer tonight..

[@stripervince1]

Hey Mark, I don't remember most of these when I worked there. I left SP signal right before the UP merger. OK you answered it. Was gonna ask if UP changed and upgraded a lot of them. I guess they did... Hey is Mickey still the lancaster maintainer?

[@MarkClayMcGowan]

Mickey went into construction (UP split maintenance and construction) and was a foreman for quite a few years. He retired around 2017.

[@stripervince1]

@@MarkClayMcGowan thanks for that info. If you ever run into any of the old gang Sp 608 tell them hi for me. John mcintyre, bruce shoengarth, terry harris dave davis ronny sisk. Thanks Mark!

[@jimeaton805]

Thank you interesting video

[@SETX_Sirens_and_Rail_02]

So I recently discovered a control point where a single track splits off into a triple track (the original main becomes the center track) and as such it has a triple head signal on the entrance. Would you be able to explain the aspects at this type of control point? Thanks!

[@MarkClayMcGowan]

Each head would control movement on a track with the top head controlling the main line, the second controlling the first diverging track, the bottom head controlling the last. There would be multiple diverging route aspects depending on various factors such as high green, red over yellow (over red?), red over red over yellow, etc. The Mojave Interlocking has similar signaling although a yard is involved. Thanks for the question and for checking it out!

[@jovetj]

The fun thing about Route signaling is it needs to be able to convey differences of routes to the train crews, but those really boil down to speed limits for the turnouts. A three-head signal would, in modern times, mean that two different speed limits exist for the different directions. But, that doesn't mean there HAVE to be two different speed limits. If you review the modern rules for UP, you'll see that R/G/R and R/R/G mean the same thing as far as the rules are concerned. It's the timetable where the maximum speeds are indicated.

[@Pasco-Spokane-Railfan-2024]

Are all the signals in UP approach lit

[@MarkClayMcGowan]

No, many are constantly lit. In Electro Code 4, the default is approach, in Microlok, it's constantly lit. Both can be changed, but any time the unit drops out and resets, it goes back to default, so most maintainers just quit messing with them. Thanks for checking it out!

[@ramongoodwin8667]

Thank you for these video. They are very informative.

[@MarkClayMcGowan]

My pleasure! I'm glad you enjoyed them and thanks for checking out my channel!

[@nickcampbell7198]

Thanks again for the information.

[@alphabarry9718]

Red on the top and the flashing yellow on bottom it is Medium Approach ?

[@jovetj]

On some railroads it would be. Not on Union Pacific.

[@ianburnett7333]

When I worked on BR lots of signalling points failures, ASE was 'Wrong man for the job'had to be paid off, replacement narcissistic told by Chairman BR Board that he was to be sacked in 6 months time unless failures dropped, bought in man from Swanley led a task force team, found lots of equipment faults reduced failure rate.

[@ebnertra0004]

Have you ever encountered an Approach Clear 60? Or one of those Diverging Clear Limited (red over flashing green)? I just built the UP signal system for a simulator and was curious how often they appeared. Also 'mixed signals', those weird combinations of high and dwarf signals

[@jovetj]

Hey you! I'm told Div Clr Lim exist(ed) here in Nebraska, but I never saw one. I've never seen a "mixed" dwarf/high signal, either. I suspect those might be long gone but never deleted from the rules.

[@briankemp5206]

Great information.

[@curtishowell428]

How long is it between blocks or mainsignals

[@MarkClayMcGowan]

It depends on the territory, speeds, braking distances, etc. but generally from one to two miles. Blocks between control points at sidings are determined by the length of the siding. Thanks for checking it out!

[@carlwedekind3868]

When passing a signal that indicates what the next signal should be, how is the distance to the next signal known?

[@jovetj]

The train crew has to be qualified on the lines they operate on. They know where every signal is, every speed limit, every grade crossing, etc.

[@Pasco-Spokane-Railfan-2024]

What is yellow over flashing red

[@MarkClayMcGowan]

It's called a, "approach restricting". Be prepared to pass the next signal at restricted speed but not exceeding 15mph.

[@jovetj]

Can also be Yellow over Lunar White.

[@perrydiddle3698]

Ok. I think I got you. If a switch is set to guide a train off the main line into a yard or siding, it is considered “reversed”. What would the opposite of reversed be? Straight through? If a train is coming out from the yard or the siding onto the main line, but the switch is NOT in the reverse position, will it damage the switch? Derail? Get through it just fine?

[@jovetj]

Normal, Closed, Straight versus Reverse, Open, Diverging

[@MarkClayMcGowan]

What Jovet said. Yes, if a trailing move is made through a turnout with the switch in the normal position, it is called "splitting the switch" and will damage the the rods and stand on a hand throw. The operating rod on a power switch is designed to shear off, but it can still damage the machine. UP policy was to change any machine after a split. Thanks for checking it out. Sorry you didn't get me!

[@jdday1757]

I'd love for you to do a video on the ex Pennsy / conrail/ NS signals in PA think they're called color position signals. They still use them on the main line from Conway to Harrisburg and some of the secondary lines such as the old mon railroad line serving the coal mines around Waynesburg and down in that area.

[@stripervince1]

When i waa a conductor for CP i worked from Binghamton and taylor yard in Scranton, going south on the river line from Sunbury to harrisburg we had the old color position lights. As soon as we got on NS trackage, Some of those signals were insane. You could have two flashing diagonal yellows over a red and lunar white. We had to break out the signal chart a lot of times there was shit like medium medium approach medium. It was crazy. They seriously need to simplify with better system

[@jdday1757]

@@stripervince1 holy hell. That is nuts. And engineers had to score a perfect 100% on the signal test as well. It's really interesting that the max speeds changed depending on what kind of train you had also. A heavy coal train's restricted could be 8 mph depending on the grade and a much lighter tofc or container train coulda been double that. So an engineer had to alter his train handling based on train type. Add for position signals go all that had to be incredibly confusing

[@stripervince1]

@@jdday1757 it was a ball of stress, you had to pay very close attention to what you were doing constantly. Not only the signals were difficult but when i worked there 20 years ago, the radios and phones were very noisy, squeally and hard to hear over the locomotives. Slow orders, track work, grade crossings train handling bad weather. Not a easy job. I always wanted to be a engineer. Until i became a conductor. It might have been a great job years ago, but today with all the paperwork and rules and regs its not. Now the cabs are video and audio monitored and recorded. You cant have a conversation about the tits on the waitress last night at sizzler. No privacy, glad im retired now lol

[@jdday1757]

@@stripervince1 when I worked for Norfolk southern in the locomotive maintenance department as an electrician we had to download the event recorders on every 3 month RM and again on any accident along with downloading the railcam. At the time there wasn't audio recording inside the cab. I left the railroad in 2011. 20 years ago woulda been when the EVO series locomotives were coming out along with with SD70Ms. Which were so much more quiet than the dash 8s or the C39-8 and definitely the SD40-2s. I dont know how any engine crews tolerated tbat level of noise. I hated self testing those damn locomotives. Plus it was hard to sleep in them and not get caught by management lol. 🙃

[@stripervince1]

@@jdday1757 yeah NS management hid in the bushes with binoculars at the triple red sidings to catch crews snoozing at 4am. Our CP trains used to used to get stopped for hours and hours at reds for absolutely no reason. Hated being on NS property. We had pretty decent engines mostly GP40s and SD70s still hard to hear dispatchers on the radios

[@adrianu399]

I’m confused when it comes to the yellow over yellow and red over yellow. Same with with the yellow over flashing yellow and red over flashing yellow. I’ve seen your first video but it seems like they basically both mean the same.. am I wrong?

[@MarkClayMcGowan]

Yellow over yellow is an approach to diverging route and is displayed at the approach intermediate signal. Yellow over flashing yellow is an approach diverging for higher speed turnouts where you can get a red over green. Red over yellow is AT the control point where the top signal controls movement on the main, bottom signal movement into the siding or other diverging route. So if you're the engineer and are going into the siding at the next control point you'd see the yellow over yellow (or yellow over flashing yellow) at the intermediate then red over yellow (or over green) at the control point.

[@MrEkg98]

Imho UP signals are goofy. I don't like route based signalling. I think speed based signalling is better. Everything here is CSX however so I may be a bit biased.

[@jovetj]

I assure you they are not goofy. The are more flexible. The western US is much more spread out, so the impetus for Speed signaling just isn't really there. Both systems have pros and cons.

[@charlesgault3777]

Is it true that some railroads also use a red over flashing yellow in a situation where the next signal is also a diverging route?

[@averageguy7136]

Yes.

[@nickastridandtoothlessthen5494]

I have seen signals on a cantilever like a crossing signal. But are connected to poles on each side in between a number of tracks (4 for example). What does that mean

[@jovetj]

It doesn't mean anything significant. The signals for each track are placed in the truss over the track it governs. That structure, with legs on both sides of the track, is called a _signal bridge._ The structures that are footed on just one side of the track are called _signal cantilevers._ These can be used where sighting distance around curves can be problematic, or where there are more than two tracks and putting signals between the tracks isn't feasible, or any other situation where the safety of maintaining them or distinguishing which track is governed is at issue. Good question!

[@ToBeDetermined56789]

It appears that the railroads interpret these signals in slightly different ways. Is there a national standard regarding railroad signals?

[@jovetj]

There is no national standard in the US. Signals evolved based on the needs of all the different railroads, and then got even more complicated when bankruptcies and mergers would happen. Most signals on different railroads are pretty similar.

[@markhoezee6292]

We have CSX tracks by us,one main track with a 3 mile or so siding, I noticed they have a three tier signal system,what would 3 reds mean?

[@averageguy7136]

Multiple diverging routes

[@stripervince1]

🛑 STOP

[@jovetj]

It means what the rulebook says it means. (It also depends on if the signal has a number plate on it, or not.)

[@derail14]

yellow over yellow on ns in called approach slow.

[@MarkClayMcGowan]

I considered doing a video on the signals of different roads but HOLY CATS! It would have to be hours long! I was surprised at how different roads can be! Thanks for checking it out!

[@jovetj]

No! Yellow over Yellow on NS _at some locations_ is called _Approach Slow._ At other NS locations, it would be called _Advance Approach._ Railroads like CSX and NS are very complicated because they have a lot of disjointed signaling practices inherited from their predecessors. Railroads like Conrail inherited all these systems and didn't unify them because it was too expensive to change/rebuild and retrain. These disjointed territories persist today. It's important to know the history of the line for the signal you're looking at, so you know which rules to follow.

[@jovetj]

@@MarkClayMcGowan Yeah, Mark, I'd recommend against you doing that. Studying the subtleties of different schemas is fun, but you have to be kinda crazy to enjoy it.

[@jerryscott8608]

Thank you very much, please checkout Danny at Distant Signals

[@timothybrown8986]

All this technology single talking to other singles and these railroads still deliver fright late. It's all bs Double track the main lines so the fright can reach the customers faster. These class one railroads are a joke.

[@MarkClayMcGowan]

On time delivery has nothing to do with the signal system other than it helps expedite fleeting moves. Main lines can't always be double tracked. Places like Tehachapi have specific geographic issues such as tunnels and 800-1,000 foot cliffs. Others have environmental issues such as the environmentalists shutting down the double track project on the Cima sub a few years ago. The Ceaser Chavez Cultural Center shut down the Rowen-Woodford project. It's too bad you see the nation's most vital transportation link as a joke. You think the class twos could operate it more efficiently?

[@edwardgray154]

just to ask did SP use cab signal system?

[@MarkClayMcGowan]

Not anywhere I ever worked, but yes, they did have it in some areas.