In this chapter we cover Automatic Block Signals. These are lights that display according to track occupancy VS absolute signals that mostly display dispatcher commands.
I read somewhere that approach lighting's origin is in the era when track signal circuitry arose in the days when batteries were the signal power source; battery drainage was minimized with approach lighting. Thanks. Enjoyed.
Thanks for posting. It's a nice refresher for me, as an ex-CSX crewman and control operator (Connellsville, PA). I am surprised to see that Seaboard and Searchlight signals are still in use. In Pa. we converted to all-Chessie signals, from the old Color-Position system. I had thought the whole system had converted. Apparently not. I'm going to check your other videos, in order. It'll be fun.
Here in Michigan, around the Metro Detroit area, we still have a lot of old searchlights still in use. There's two in South Lyon and quite a few in Wixom.
Nice series Danny! As a signal electrician(or maintainer) as you call them over there, I find this very interesting to see different systems in place. Approach lit signals save power and extend lamp life as others have suggested, it also checks the health of the track circuit in the electronic interlocking and the health of the lamp/led in the head. LED lamps don't last as long as you would expect and the old bulbs would last for years, but LED;s are becoming more reliable and they do give a broad light which does not need close focusing like old style lamps. Thanks again and always enjoy seeing and hearing your voice mate. Cheers Gregg.
+FishplateFilms WOW! Many thanks, Gregg. You're the first to explain the reason behind Approach Lit signals. That's really interesting about the LEDs, too. I have noticed that on the new lights with LED's, there are no fresnel lenses. So I guess no focusing is needed.
Approach lit signals were originally devised in the early days of railroading when many remote locations had no electricity and were instead powered by long-capacity deep cycle batteries to reduce the frequency with which crews had to replace said batteries. (Also before the days of solar charging). Because it was easier just to put electricity to the cabinets without making changes to the system the approach lit system with searchlights continued on. As railroads (CSX and NS in my area) are replacing the systems end-to-end with Vaders (aka Tombstones, or officially Safetran ColorLights) they are eliminating the approach lit system due to lower power consumption and longer life of the newer LEDs. The track circuit testing mentioned above only partially applies as even with non-approach-lit signals they remain at red when the block approaching them is unoccupied, so if the track circuit fails to detect the train they will remain at red, not "fail" to a green and cause havoc.
Thanks for the info! I don't think we used batteries down here much and approach lit is a newer thing on newer interlockings. Any signal not lit is taken as red and no signal should "fail to green" , thats a "wrong side failure" down here and is big trouble! Signals in remote areas are often solar powered with batteries and are approach lit . Very interesting to see how things are done elsewhere. Cheers Gregg.
I didn't mean to imply that a signal should fail to green at any point, but that relying on an Approach Lit system to indicate whether a track circuit is operational or not isn't necessarily the case, as you'll notice it on a constant-burn ABS signal as well because it would never change from red whether a train is on the circuit or not, if there was a failure. Interlockings in the US were rarely, if ever, approach lit due to the importance of being seen at any time, plus being near power anyway due to the control towers nearby (whether or not the tower was powered by electricity or batteries, there was enough power to burn the absolute signals 24/7). Batteries aren't used nearly as much anymore since the cost to get power to even the more remote signals is much lower. But in the early 1900s when semaphores were being fitted with lights to improve nighttime visibility, many signals couldn't be reached by electric lines without breaking the bank, so it was cheaper to put long-life batteries at each remote location instead. Approach-lighting them meant that the batteries had to be changed less. As I said, even when electricity was later run to these locations it was easier just to leave the existing relay circuitry as it was, so approach lighting remained. With the mandate to have Positive Train Control on all Class I lines many railroads have found it makes more sense to replace the entire signalling system with new systems end-to-end to be able to implement it properly, and in many cases approach lighting is not being seen as necessary in these systems as there is no need to conserve battery power, or save filaments from burning out. On the LED note, a caveat is that railroads can no longer monitor the lights to ensure they are working. With incandescent lamps a small voltage could be constantly put through the lamps to monitor filament status, allowing faster indication when a lamp burnt out, but this is not possible with LEDs so they have to rely on reports from engineers and track inspections for the rare occasions an LED does fail.
Hi Danny, as per your question about why the signals go dark after the train and light only as a train approaches. I actually asked a few CSX signal maintainers about signals being dark and only lighting when a train comes and then goes back off{dark} after the train has passed. What I was told is that the signals in some locations are strictly battery powered and today, may even have solar panels to keep the batteries charged. So they light as the train approaches and go dark when the train has passed, to conserve the battery power that may be in use. They all also all contain battery backup for when power fails as well. So, again, just to conserve the battery or batteries from being drained/depleted dead by having a signal remain on, when it would be unnecessary. Maybe if you can ever catch a signal maintainer he can either confirm this or give you some other explanation as to why they are set-up like this. But I talked to quite a few in my rail fan days and this is the explanation I got at the time. Sounded reasonable to me
I'm a signal maintainer for KCS and you are correct. If no train is in the area then there is no need for the signal to be lit so it goes dark. For the most part when I signal is lit and no trains are around that means you have a problem that we call a "track light" which means you get to go to work at 2am and find the problem lol.
We have that up here on the CP. The signal goes dark right after the train passes it. I’m surprised that the train doesn’t wait till the next signal before it goes dark again!
In the UK there’s a different kind of permissive signal. Shunt signals are kind of like dwarf signals and are used for controlling trains in yards. They can display two aspects: Two white lights means “Restricting” while a red and a white means “Danger” or “Stop”. The permissive version of this signal replaces the red light with a yellow one to show that it’s a permissive signal and that some trains may be allowed to pass the signal when at danger
Danny, I think that this series should go on if you see more different or even the same. Also, if you can, you can make a signal quiz to see what the indication is displaying, and if it is an Absolute, ABS, or a holdout signal and maybe a location of where the signals are. Anyway, this series was fun, helpful, and awesome.
I wish I believed that I could memorize all this. Yet I know train crews have to. I'm glad they believe they can do it. 6:52 Light power is my favorite.
I always like how the distance compression from a camera lens can show just how drastic a grade can change over a 5 or so mile distance, and how much a train is actually rocking back and forth, even on rail that's seemingly perfectly level to the human eye.
It would be a good assumption the "light on approach" signals are done that way to reduce power consumption. Also may extend the lamp life. These issues wouldn't be as critical on newer signal models that use LED's for the light source.
There is also a “D” plate for a distant signal. Up here in Wisconsin, on the Union Pacific Kenosha Sub, most of the line is dark territory, except for the power plant at Oak Creek. Basically our distant signal is like your fixed approach, it doesn’t tell you about track conditions ahead, it tells you that there’s a more serious signal ahead. The only difference is, this type of distant signal has two lights, a green and yellow, or a two over one light, green-yellow with a single yellow for a diverging move at the signal ahead!
Starting around the 0:10 mark of the video I like the mention of the discussion of what British railroad terminology is often called a SPAD (signal passed at danger). It's good that a SPAD appears to be punished by railroad companies because such incidents can be fatal (and far too often have been).
@@viktorgaragedoors331 I can understand why those railways, wherever located in the world, that do have zero-tolerance rules for SPADs have such rules in place.
In the northeast, we operate under NORAC rules. The signals in general are very similar. One major difference is that we have stop and proceeds instead of restricted proceeds.
They changed the signals here in Oklahoma to the darth vader style signals.They all stay dark until the train gets within 5 or 10 miles of the block. They used to light up long before the train got there. They've taken all the fun out of train spotting.
Thanks Danny your videos are so educational and informative I lived by BNSF Houston Teague Somerville branch and all they had was standard signals they weren’t CTF controlled they should’ve been I live right beside milepost 79 and that’s what got me interested in railroading today since 1972😎👍
Superb video, Danny! your discussion of signal markers, including those in ABS territory displaying a Stop indication was right on the mark. I assume you follow CSX only in the South but, were you aware that CSX also operates under B&O signal rules toward the North with different seniority districts? Eventhough the northern territories are upgrading to "SCL" signals, there are two signals (in each system) that defies normal, conventional signal logic. Could you point out which ones these are for both districts? Otherwise, the other "common" B&O signals are the same.
B&O CPL signals cannot display the Seaboard "Advance Approach", and Seaboard signals can't display the B&O "Slow-Approach-Slow" (only shows green lights in the main signal face, with no pilot light). Typically, in former B&O and even RF&P territory, CSX uses either "Approach Medium" or "Approach Limited" in place of Advance Approach, where there is no diverging move possible at the next signal. (I was a Baltimore-based CSX engineer, and a real fan of the old B&O CPLs).
@@paulw.woodring7304 I feel like CPL signals are the best of both worlds. They're modular, which means you can add or remove pairs of lights as you wish, but they're also indicating any given rule in TWO ways so you don't mix anything up if red looks like orange or something like that.
Hello Danny, the reason for the ABS signals being off when there isn't an approaching train is due to these signals having battery backup in case the AC power is lost. During times when battery backup is in use, approach lighting extends the battery back up time by lighting the signals only when they are needed. A battery charger connected to rechargeable batteries is located in the signal house or case. Great video posts!
One would think in the year 2021, a email from a dispatch with instructions, like old TWC, would totally remove Human Error. In my youth as a Conductor on the Southern right at the Merger , the Cab Radios were awful with 3- 4 trains on 1 channel in busy areas, it was very annoying, I'm glad I had a very early flip phone to call and verify every move.
Hi from Europe. I am just curious about one thing: In Europe, on not so busy lines, we often have signalling arranged such a way: Imagine two stations 20 km apart. And there is just a single block between them. The exit signal at one station will, however, show a "clear" signal aspect even though the entry signal is at "stop". That would be too early to warn the driver/engineer about the status of signal he will approach 15 minutes later. The entry signal has its own so-called "pre-signal" just braking distance away. It has just two lights: yellow+green. The Pre-signal doesn't divide the block between stations to one long and one short blocks - it has no red light, it can not divide blocks at all. Is something like that serviced in North America at all? I always thought it was the distant signal, but now I saw it go-to red. Our European pre-signals do not have joints nor axle sensors with them. They simply turn yellow as late as the signal they repeat does.
So “ABS” means the opposite of “absolute”. I swear they set these things up to be confusing. In aviation, they would immediately see that some day, somebody will have a brainfart and interpret “ABS” as meaning “absolute”, so they’d choose alternative nomenclature to avoid even the possibility of confusion. At least, in this case, misinterpreting “ABS” makes the signal more restrictive, so the system fails safe.
Having driven trains myself in the Netherlands, i'm actually quite surprised that these signals look pretty simulair to the ones we have here. especially with the permissive ones which work pretty much exactly the same here.
We have NS that comes to my plant to switch cars. The grade crossing (which has no gates) bells and lights were going. Called NS and gave the grade crossing number. NS came out and found that a bond wire on the plant side had been damaged and was no longer connected to the track. They done something in the grade crossing electrical panel, reconnected the bond wire by thermite welding and resolved the problem. Still not sure why this all happened or the logistics of it as I was unable to speak with the NS Technician.
True: A signal maintainer with a key can unlock the door and mess with the signal lighting, timing, etc and can set it to continuous or full time mode or can set it to light up when a train coming a few blocks down.
We hade a crossing signal in my town where the motor running the gate seized up and left the gate at about an 15 degrees off parallel from the street. Then it wouldn’t go up or down. They had to come out and replace the whole gate mechanism with a new one. The gate was getting pretty old anyway, it had no reflectivity left in it. So they replaced it as well. The really weird part was that a month later they took the old signals out and built totally new ones with LED lights, Cantilevered over the road, sidewalk gates, the whole nine yards. Even used mechanical bells for a while until one day when those were switched out for electronic bells. The new crossing signals protect 16 tracks. Your basically going through the center of the railroad yard here. Oh, the built an island in the street and put another signal and gate facing the same way but across the street from the cantilevered signal on both sides of the railroad crossing. One more thing. The trains no longer blow their horns. The sign approaching the crossing says, “No Train Horn.” I miss that, not hearing the trains blowing their horns at the railroad crossing.
I got a question, I live on NS rails but it also applies for CSX. So their was a EB train yesterday and behind it was another EB Intermodel and they asked dispatch becuase the 1st train was 8 miles ahead of it and so the 2nd train was coming up on a intermediate signal and it was still restricting and they asked dispatch and said " yeah this signal should have cleared up to approach by now " but it went from restricting to a straight Clear. Do you know what the reason might be scince it went from Restricting to Clear istead of Restricting, Approach and then Clear ?
SIGNAL INDICATION + LOCATION TIMESTAMPS ~~~~~~~~~~ 0:00 Clear at Rockport Wye 0:05 Stop at Lee 0:13 Stop at Lakeland Junction (??) 0:17 Clear at IDK 0:27 Clear at South End Carters Siding 0:33 Stop at Plant City Holdout / A-Line 0:38 No Indication at IDK 0:45 No Indication at Dyal Hill 1:01 Stop somewhere near Dade City 1:12 Stop somewhere on the XS line 1:33 Clear on some branch line 2:19 Clear and Approach at Soutel / Jacksonville 4:22 No Indication at Dover 5:03 Clear at Distant to Winston / Plant City 5:42 Intro 5:59 Clear at Distant to Cherry Siding / Plant City 6:59 No Indication at Alifia River Draw (Stop & Check) 7:43 Clear at Zephyrhills 8:18 Clear at Distant to Zephyrhills/Vitis Jct 9:22 Clear Distant to Lochloosa Siding
Could you be so kind to tell me where I can find old signals in California closer to San Jose? I mean signals which have only one lamp with three color light filters.
The type you're talking about are the old H2 signals with one 25watt 10volt bulb on a moving magnetic 3colored lens red yellow and green called a roundel . When I worked for southern pacific in the early 1980s, we ripped out the old red line from Los Angeles to almost San Bernardino. A lot of 1940s-50s equipment just sat in our yard for decades in a junk pile. Signals, wig wags, (worth a fucking fortune now) signs, ecm insulators purple clear and amber and aqua blue ones, some super super rare on cross arms etc. I don't know about up near San Jose, but go rummage some old desert branch lines near Mojave and tehachapi and Bakersfield. Look in train yards and scrap piles, that aren't fenced in try not to trespass, most are still unfenced. might find some good shit like date nails on old ties and other goodies. Those signal heads weigh a lot, I mean a lot. Good luck carrying one if you find one.
Can someone tell me what the siding signals between Maryland route 97 and Morgan station road in Maryland is? After a train goes through they stay on, but there isn't a train in the block. They are ABS but don't turn off after a train goes through.
At 0:26, it seems that, since the two signal heads are spaced far apart, the bottom head indicates Slow Speed instead of Medium Speed. Is that correct?
I'm only at 7:32, thinking I'll be interested to hear if these signals have a "failover" aspect such that if, for instance, the "G" or number tag goes missing, they are to be interpreted as older-style absolute type. I suppose the designers take all these things into account.
Good question. Yes, crews are supposed to know each signal on the line they operate. When they see a signal that's missing it's number plate, I would guess that have to treat it as an absolute stop signal, but I don't know.
What is the meaning of the sign at 3:36? Also, on signals with a C plate, like the one for the bridge on this video, what other indication could that signal display that would have to do with the bridge itself? Could someone explain signals with the C plate to me? I don't fully understand them.
The sign at 3:36: It's a Warning Board. Tells the train crew that two miles ahead is either a speed restriction or beginning of a maintenance work limit. The train will have to slow down or call the foreman to get permission to come through the limits ahead. This is a temporary sign that the road foreman will remove when the track work is done. Sometimes next to this sign, a solid yellow sign is displayed. It tells the crew to reduce speed as ordered in train messages. If it was a solid red, it would be a conditional stop sign. Which means stop here, and don’t go any further until the employee in charge gives you permission to do so. A solid green sign tells the crew that they are leaving the zone and can resume track speed. Basically a C plate is an "INTERLOCKED ABS SIGNAL." It is mainly used near a draw-bridge. The C plate means a "STOP AND CHECK" signal if the light is red. This means that the draw-bridge is open or anything is out of alignment, the train crew can't move until they check the bridge and then contact dispatch. If the light is green, that means the bridge is aligned and locked and the train can proceed at restricted speed.
I have a question why do locomotives stay on when they are stationed somewhere on the side of a track and why auto turn on and off for a while like in days ?
What’s the name of a signal when it stays yellow and never changes color? Because I have footage of a yellow signal and it had a letter plate but it was a good distance away and I couldn’t make it out but when Q315 the daily Intermodal to Norfolk passed the signal, it still stayed yellow. When Q316 went the opposite direction of Q315 (which was coming from behind the signal) the signal still stayed yellow. This was odd and there was a hill behind the yellow signal so I couldn’t see if there was another signal. A possible serious signal. I don’t know. But do you know what those signals are called if they are always showing a yellow and nothing else? Maybe a possible APP signal?
Hey Danny, I have a few questions. On a calendar train picture I have, it's the Chicago and North Western Railway heading West at DeKalb, Illinois. The train passes under a concrete coaling tower. There are two signals that are 2 headed signals with 3 lights on the top and 2 lights on the bottom. The first signal on the left shows a Steady Yellow light in the middle on top and the second light on the bottom signal is Red. What does that signal mean? The signal has a 572 plate and below the plate is a "Yellow Square "P" Plate." The other signal shows a Red light on the bottom of the top signal and the bottom signal has its second light red. Is that just a Stop Signal?? So it has a 574 plate with a "Yellow Square "P" Plate" as well. So does that mean those signals are Distant, Intermediate or ABS Signals? The 572 and 574 numbers, are they Number Plates? And does the Yellow Square P Plate mean it's a "Permissive Signal? Thanks!
The exact interpretation of the signals may depend on the year of the photograph. But, the first signal is an _Approach_ signal. The second one is likely called a _Restricting_ signal. Those signals are likely to be Intermediate signals. You can tell they're intermediate signals if 1) they are in Centralized Traffic Control (CTC) territory, and 2) they have number plates (the "572 and 574 numbers" you speak of). Intermediate signals are also permissive. "Permissive" generally means that they *_can be passed_* by a train when all red. (Contrast this with _absolute_ signals which cannot be passed when all red, unless a dispatcher gives very specific 1-time authority to do so.) CSX is a bit screwy when it comes to some terminology. "ABS signals" only exist in Automatic Block Signal territory. You may see this on a timetable referred to as TWC/ABS or DTC/ABS. Track warrants are still required in this operating mode; ABS signals never grant movement authority. The signals are not controlled by the dispatcher, and only exist to space trains out and add a layer of safety. ABS signals can be absolute or permissive, just like signals in CTC (but for different reasons). It's reasonable to guess the photo you speak of shows CTC territory; as I recall, the C&NW was an early adopter of CTC (and ATS) between Chicago and western Iowa. The "P" signs are the C&NW equivalent of a "G" sign that most other railroads have used in the past and now. It means that, when all red, the signal does NOT mean _Stop and Proceed_ but instead means _Restricting_ (or something equivalent). The CSX "P" signs are a peculiar holdover from the eras when CSX still used _Stop and Proceed._ As currently implemented, a "P" sign or a number plate in CSX/former-SCL-territory both indicate a permissive signal indicating _Restricted Proceed_ when all red.