How Railroad Crossings Work

[@PracticalEngineeringChannel]

Happy New Year! What other burning questions do you have about railroads?

[@chrisharris7893]

Defect detectors!

[@yk.dezire]

You should cover defect detectors next!

[@stabilini]

Happy new year Grady !!! This series is awesome... can't wait to signaling videos, I think it would be a series by its own. Another great thing are gravity yards.

[@feuermurmel]

Hey, could you at least acknowledge in future videos that the railroad-related information you present only applies to NA (when that's the case)? At least in central Europa, with few exceptions, at-grade crossings work nothing like you presented in the video. Thanks!

[@Nthuziast]

do one on the function of old railroad crossing signals like wigwags and griswold rotating banner signals

[@danieljohn560]

Thank you for including the blue sign with the crossing information. If you're ever stuck on the tracks the first thing you should do is call that number and give them the crossing ID. It is the fastest way to stop a train.

[@major__kong]

All gas stations have an e-stop (big red shutoff button) for the pumps. Learn where it is for the gas stations you frequent. You may need it one day.

[@BrainScramblies]

I've used one of these myself just to call and let them know that a pedestrian gate was stuck down. People were walking Around the gate and that's a dangerous habit to form.

[@davidgates1122]

Wouldn't shorting the rails with your jumper cables (in addition to activating the crossing signals and gates) also turn the signals on that section of track red to warn any approaching train that there is another train on that section of track?

[@Stameboat]

Only in PTC protected track and even then it’s never fool proof.

[@HyenaEmpyema]

I've wondered the same thing@@davidgates1122 My guess is the cables might not get a solid grip on the rails, but it wouldn't hurt to do it *after* you dialed the phone number on the blue sign.

[@paulbaird205]

I saw a car drive through a RR gate. The care kept on but the damaged gate was bent in towards the rails and it was struck by the passing train. Within 5 minutes, UPRR was on scene and the gate was replaced and operational within 30 minutes. It was impressive. I was waiting for an autoshop to change a battery in one of their fleet vehicles I was picking up to take to auction. So, it took longer for a auto repair shop to replace a battery than for UPRR to respond and repair the crossing gate.

[@MaskMcGee]

Its more a necessity than impressive. Can't wait around a week for a broken gate to get fixed, if someone drives onto the tracks and gets hid by a train because the railway's crossing was broken they have a big legal problem. They can't stop running trains for a week for the gate to get fixed, as the cost of downtime is in the thousands if not tens of thousands of dollars per minute. Anything on the railway goes wrong they have to stop everything at huge potential losses so extremely quick fixes are the way every problem has to be handled.

[@ThinkTooMuch69]

@@MaskMcGee”cost of downtime”…. You mean they’re just not making money

[@nothisiskas]

​@@ThinkTooMuch69 no, they're actively losing money

[@joshyoung1440]

​@@MaskMcGee no. Stop. Something being necessary does not affect how impressive it is to someone else. Stop trying to ick someone's yum, and more importantly, stop discouraging others from saying kind things.

[@joshyoung1440]

​@@MaskMcGee everybody knows it's necessary. It's so blindingly obvious that that's the reason they do it, I just don't think anybody else thought it needed to be said. They just kind of understood that pointing out the obvious wouldn't make them sound smart.

[@eaglescout1984]

14:31 If you ever see a vehicle stuck on the tracks, call that number FIRST. Many people end up dialing 911, but the time it takes for the 911 dispatcher to understand what's going on, get your location, determine which railroad to call (if there are multiple tracks in your area), call them, relay your geographic information, and have the train dispatcher figure out which crossing that is can be avoided by calling the blue sign number. It's a direct line to the train dispatch office and that crossing ID lets them know exactly where the issue is and they can notify any approaching train in seconds.

[@kenbrown2808]

get the PEOPLE off the track first. THEN start calling.

[@ViolletLaDonPin]

@@kenbrown2808 thank you mr. obvious

[@mbryson2899]

​@@kenbrown2808 Excellent point! Get the occupants out and away to a safe distance. Then call the RR. Then, if time and situation safely permits, push the vehicle off the track. I grew up in Chicago, there are lots of street crossings there. We were actually taught all of the above in junior high, then again in high school.

[@LupeCoded]

I did not know this. The suggestion is greatly appreciated.

[@Name_Nah00]

@@kenbrown2808 That isn't always an option.

[@Trainfan1055Janathan]

Never assume the crossing is working! When I was a school bus driver, I waited at a crossing because I saw a train was approaching. The crossing didn't activate until the train touched the island circuit. I reported it and they repaired it the next day. Usually, they'll approach the crossing slowly and flag traffic as they cross in situations like this, but they weren't aware the crossing wasn't working and crossed at around 30 mph.

[@RoelBaardman]

I worked in the Dutch railroad management software for a bit. The most tricky situation we encountered was a train that crossed a road, stopped at a station for 10 minutes, and then departed in the opposite direction.

[@MP-oh9lt]

I somehow don't see a big problem. Care to explain?

[@frafraplanner9277]

That's definitely a troublesome edge case!

[@MrDan961]

We use DTMF codes for trains to activate and deactive crossings they are stopped near

[@annabelholland]

That used to happen at Ely railway station where EMR (East Midlands Railway) used to reverse at the station coming to and from Norwich (Liverpool to Norwich service), using the crossing twice. The level crossing was used by tall vehicles with an underpass for cars and bikes. Since a new bypass was built around the level crossing and the town, the level crossing is now gone. This shows why level crossings should be closed when there are at least three tph per direction

[@supernenechi]

Which station, if I may ask? From personal experience I believe this is kinda common.

[@Mr2ronron]

As our Company makes components for vital relays, your video is going to become a must see for all our employees. It helps to understand where what is being made is being used and why getting it made correctly is vitally important.

[@Oz_Gnarly_One]

The importance of vital relays is certainly drummed into the workers installing them in the field. Lives rely on these working within specification.

[@jasonschubert6828]

I really like the idea of Japanese railway crossings where they show the direction of the train's travel. It is a great way to show that the system is not malfunctioning after a train has passed and a second is due in the other direction.

[@raymondhopwood9393]

I also like the idea of signs that flash when the nearby crossing is about to activate its warning devices.

[@beyondEV]

@@raymondhopwood9393 We kind of have that, i the sense, that the lights start flashing about 5-10 seconds before the gates start closing. (Switzerland). Unfortunately drivers often see this as a yellow, so they will keep going until the gates come down. Good news is: 1970-1999 you had a average of = 118 accidents on crossings per year; 2000-2008: 42, 2009-2016: 11,75, 2017-2022: 5,5 Think it was mainly, that the got rid of any unguarded crossings. And improved the rest (basically all have 4 gates). That is despite having a lot more and faster trains operating per day.

[@beeble2003]

@@raymondhopwood9393 Flashing lights are already one of the warning devices! You don't need flashing lights to warn you that the flashing lights are about to flash.

[@beeble2003]

@@beyondEV The flashing lights _are_ a yellow! They have exactly the same meaning: stop if it's safe to do so.

[@Menoetia]

0:47 I'll add to this: if YOU can see the TRAIN, it's too late for them to stop in order for them to avoid hitting you. My spouse is a former Union pacific engineer and has come home with too many stories of close calls because people were willing to risk their lives to save fifteen minutes waiting for his train to pass. Also important: some grade crossings do not have rails or lights to warn you of oncoming trains. If you come across one of these, stop and look both ways up the track for headlights (trains almost always run with their lights ON) and if you see headlights, don't cross. You don't know if that train is going 15mph or 50mph, f they're a mile away or a quarter mile, but the time to find out is not when you get stuck on the tracks.

[@nukehunterlp1371]

It's quite interesting to see that apparently in the US the railroad crossings use track cirquits to detect whether a train is approaching or not. Here in Germany, they all work with directional switches that are activated by the train's wheel, and the crossing is opened with axle counting switches before and after the road. Basically if some amount of axles entered the road section and the same amount also left it, the safety devices shut off.

[@maciejzettt]

I'd say it's a standard in the EU now. All new actively guarded rr crossings built in Poland use axle counters

[@m0llux]

Yeah, in general it seems that American railroads (or the regulators) seem to focus less on preventing accidents, but instead they build everything railroad related like a tank so that on case of a crash, there are less deaths. A good indicator is that many railroads in America still use Track Warrant Control, essentially a glorified version of what we Germans know as "Zugleitbetrieb" or "Fahren auf Befehl".

[@jovetj]

@@m0llux I disagree with that assessment.

[@SimonS44]

There are several different ways for railway crossings in Germany: axle counters are one, but there are others that are automatically closed when a signal is set over it, or the signalman has to manually close them from the signal box

[@marco23p]

Is it all axle counters in Germany? In The Netherlands, most of the network has track circuits as well.

[@1911wood]

I’m a school bus driver. A fella came to speak to us about crossing safety. On the topic of evacuation of the bus because of a possible impending collision/derailment, we should direct the student in the general direction the train is coming from but at an angle so that every step move us away from the track. So if the train is expected from the north the we should move to the NE or NW. The idea is that collisions frequently result in the train derailing. At that point the cars and cargo can be thrown far from the track. The derailment is mostly down stream from the point of the collision (that isn’t always true) so don’t move in the direction of where the cars will be derailing. So move upstream and away from the track.

[@seaofred88]

As a railroad signal maintainer you did an excellent job explaining this. I wish I had you when going through training haha

[@boyd19043]

I 2nd that

[@Oz_Gnarly_One]

Certainty better than the decades old stuff they teach us on lol. We don't use predictors etc where I work so that was interesting.

[@Drunken.Kitten]

what voltage/amperage is used in a system like this? im assuming 24v/sub amp levels? had a shop teacher back in highschool have us help him build a train cart to get to his fishing spot up north, said if you bridge the rails it could kill you... seams highly unlikely to me.

[@seaofred88]

@@Drunken.Kitten I’m not sure on the exact voltage for our crossings but it’s very low. If you bridge the rails you don’t even feel it. It’s more of a frequency that we put out on the rails, and all crossings in the the area are different frequencies so their signals don’t overlap

[@Drunken.Kitten]

@@seaofred88 okay, that's what I thought. Is it controlled analog or with digital mosfets or something like that? On city power I'm assuming with battery for back up?

[@erutuon]

You answered a question that I had forgotten. On a road next to a light rail line, the lights go red when the train passes. I always thought this was inefficient because there are no cars crossing the rails and the road while the crossings are blocked, but now I know the lights for the streets going across the road are green to ensure no cars are stuck on the rails between the arms and traffic on the road. I'll probably still feel it's annoying, but at least I know it's necessary.

[@ralfie8801]

They should only remain red for a couple minutes until there’s been enough time for the crossing to clear, and then the adjacent road should go green. We have some traffic signals like that in m6 area that usually work pretty well. But they do stay red for extended periods sometimes, and when that happens the traffic signals flash red so you can stop and then proceed as if you were at a stop sign.

[@AaronOfMpls]

Yah, once the crossing _is_ clear, it's common for the traffic lights to go green for the road paralleling the tracks. Nice that trains also trigger the flashing white lights that show the traffic light is being overridden too -- the same way emergency vehicles do.

[@bvoyelr]

I firmly believe this video exists mostly to allow Grady to write off his nascent model train collection. It also helps that he was programming these train intersections for use in his model train track -- all he had to do is film it and provide the narration.

[@WoodFamilyRu]

He is really fond of making these models in his garage 😊 Great hobby, useful for many people 😀

[@LuisSierra42]

I was thinking the same thing

[@freetolook3727]

The inner child comes through! 😂

[@RCAvhstape]

I hope he's building an outdoor garden railroad, so he can put all his civil engineer skillz to use.

[@captainjennifer]

The models, run thru a number of ways, really helped for understanding. I'm just not as smart as the rest of ya.....

[@jimsannerud6254]

I grew up near grade crossings for high speed commuter rail. We were taught from an early age to "Stop, Look, and Listen." With two tracks, sometimes the gates would be down with a train stopped at an adjacent station, but what you had to be aware of was the possibility of an express train approaching from the opposite direction. Unfortunately, a high school classmate of mine was killed by a train in exactly this manner.

[@liam3284]

Yes, I have seen a few people also push through because they are trying to board the train entering the station, not realising an express is coming the other way. Fortunately they were near miss, but still concerning.

[@tis7963]

I live in the Kansas City area, so I've been crossing railroad tracks since I started driving. Crossings have improved dramatically in that time. Forty years ago, it was common for gates to stay down long after the train was gone, or to close when there was no train. Trains sometimes moved at a walking pace through crossings, or stopped completely, blocking the road. I haven't seen any of those problems in decades.

[@jovetj]

Those "problems" still exist. Technologies like grade crossing predictors help, but trains going slowly or stopping on crossings still happens, usually regularly at the same crossings.

[@57thorns]

@@jovetj I think it is more likely that those problem have either been solved locally, or that tis7963 has moved to a part of the city where this is less common.

[@somebod8703]

I suggest watching the "freight trains" episode of "last week tonight"

[@ConstantChaos1]

Then you just aren't looking, trains arr getting so long that ambulances are stuck waiting on them for HOURS at a time and children literally have to climb under train wheels to get to school all over America. I'm glad you aren't dealing with it now but literally all of these problems have become exponentially worse in the last 8 years

[@ConstantChaos1]

​@Catherinefox-tg5hk what are you smoking? The economy is doing better than it has in ages here and this also has absolutely nothing to do with the topic

[@phoenixaki3458]

Loved the explanation of how the circuits tend to failsafe towards assuming a train is coming - we had a winter storm a few years ago that had very strong winds and caused widespread power outages in my area and I was driving home from work that night and a local train track had lost its power and was stuck in the "train is coming" state. All of the drivers near me waited a good ~5 minutes before carefully (and terrifyingly) navigating our cars around the gates because there was no alternative way to get home without going over a similar track elsewhere

[@johnschultz9023]

Chances are a track circuit went down. All crossings have battery backup.

[@wraithcadmus]

A common feature at extra-urban railroad crossings in the UK (or level crossings as we call them) is a handset that connects you directly to the signaller. These are generally meant for farmers who may have long and slow vehicles that might struggle to cross in good time, or even trying to drive a herd of animals across.

[@beeble2003]

There's a telephone like that at every crossing in the country. Anybody with a low-clearance or slow vehicle is obliged to phone for permission to cross, and then phone again to confirm the crossing is clear.

[@distantsignal]

Excellent video, AGAIN, Grady! Thanks so much for the shout-out, too!!

[@HyenaEmpyema]

Great video Grady. What amazes me is how reliable these circuits are. Yes I know, they can and do malfunction, but generally speaking, they are outside in harsh weather conditions and mostly just work 24/7 for decades as you said. Another reason they use current on the rails to detect trains (instead of a radio transmitter in the cab) is that sometimes railcars get disconnected and roll down the rails un-commanded. If they assumed that only locomotives can control the arms, this could lead to a runaway railcar buzzing through at high speed without any crossing arms at all!

[@paulhintz9570]

I'm a retired railroader... great videos. I love watching all of them. you don't know how many incidents I've had in the time running trains and inspections. Heat kinks, hitting parked cars and incidents at both passive and gated crossings and you covered the newer predictor circuits as well!

[@myfavorites1016]

I have a question , sometimes the crossing arms are down when the train is getting near the crossing, then the the train stops and gates go back up , then the gates comes down and train comes through the crossing, thank you

[@deadhamster7570]

German (and many other European) rail networks use axle counters to determine the number of axles rolling in and then out of a section. They are more robust against contamination and don't pose the problem of having to isolate a section of rail. The downside is that they can have a counting error on the entry or exit, which leads to the signalling of an occupied section. Another very cool system is the European Train Control System (ETCS) which is currently in the roll-out across the different national rail networks. It allows for continuous supervision of the trains and has some features build in for autonomous operation. It also allows for high speed trains that drive faster than the driver could identify signals or even brake when a train in front has to brake. There is quite a lot more to consider when your trains go faster than 180 km/h (110 mph).

[@matejlieskovsky9625]

Yeah, really looking forward to full ETCS roll-out here in Czechia. European railway tech is really awesome.

[@matthewmaxwell-burton4549]

The tgvs in France use the rails to transmit the block data directly to the cabin. And etcs does that too. But it's not all that great for the infra side. Each information point has to be doubled, and the devices used to check if it is working emit so much radiation that men are asked to get off the track when doing a reading. Moreover there's only one company that sells these devices and they sell it for 10K + you have to buy their tablet to connect to a wifi access point that points you to a web page. ETCS isn't compatible with last minit speed reductions used in track replacement worksites, as you have to send off the calculations to the manufacturer who takes X time to reply and bills each calculation 15K. The tech is good but the implementation is messy.

[@ThePixel1983]

​@@matthewmaxwell-burton4549We really need laws that make it so that systems are developed for the public hand, with open specifications.

[@paulzagieboylo7315]

These axle counters also mean that trains in Switzerland are legally forbidden from having exactly 256 axles. Because the old axle counters use an 8-bit counter, and a train with exactly 256 axles would just ghost through invisibly!

[@matejlieskovsky9625]

@@paulzagieboylo7315 that's hillarious! Is that really true? When are they going to phase out those old counters?

[@illestBadMON]

as a signal maintainer in the NYC area, you did a great job at explaining crossings. it does get a little crazier with all the relay logic that's required for everything to work flawlessly. F.R.A testing that's required either monthly/quarterly/yearly (Test 27 a,b,c) all play an important role in keeping things safe.

[@mattsbro92]

FRA Part 234 keeps us busy

[@johnschultz9023]

I prefer relay logic.

[@uzaiyaro]

Here in Australia, traffic lights are often integrated into the railway crossings, so the traffic light controller is aware of the location and speed of trains and this dictates the stopping pattern. It’ll let traffic go only in certain ways for as long as the gates are down, and as soon as the gates are up, the lights change. It’s a pretty cool system.

[@jovetj]

The same concepts happen here in the USA. The term is "traffic preemption" but that generally is only on the level of the traffic controller being told YES or NO there is a train coming. The railroad equipment has all the speed/timing information and simply passes the message on to the traffic signal control when it's time to.

[@chrisharris7893]

Yes it is amazing. I watch the signals around the Baltimore Light Rail coordinate with the train. The train travels down major city streets as well as grade crossings in the county. There are extra electronic signs to let drivers know what is going on. Seems to work well even between stations that are close together.

[@jovetj]

@@chrisharris7893 FYI, those signs are called "blank-out signs"

[@EngMadison]

Yes, when a Railroad crossing is integrated into a signal, they go through a pre-emption process. This involves ending whatever phase is active and going to a track clear phase to flush out traffic over tracks. Then to a dwell phase which allows non conflicting movements to go. It can also cycle other non conflicting movements during a train. I'm currently working on a traffic signal that will allow pedestrians to cross the parallel major street during a non-conflicting train by using special ped phases only ever active during a Railroad preemption event. This is all somewhat similar to emergency vehicle pre-emptio, except trains hold a higher level of urgency and can get away with short changing phases more than say a fire truck.

[@jovetj]

@@EngMadison ???

[@anarfox]

In Sweden, most crossings have gates covering the whole road surface on both sides of the track. That way you can't drive around them, you have to drive through them. Most people aren't that impatient. And for those wondering what to do if you get stuck between the gates, you drive through them. They're designed to break from the forces of a moving car.

[@JimE6243]

Great stuff Grady! As a current 80 year old who grew up close to RR tracks and spend many hours walking them and watching them. I really like this series. It brings back many childhood memories. Trains fascinated me back in the late 40's and still do today. Thanks for your time and content. JimE

[@BOZO1959]

You really did a good job of showing how a grade crossing works, I was an instructor and a assistant inspector of signals for a railroad in NY, retired now, all we have to do is instructor people not to cross tracks until the gates are up and at rest or not to race the gates but if they do get caught on the tracks that the gates are meant to break way with minimal damage due to shear pins holding the gates.

[@ViewlessSquid]

Signal Maintainer here. Excellent video. The coordination with crossings and traffic lights is called preemption. You really hit on a lot of information that didn’t dive real deep, but just enough that would allow people who want to geek out on this stuff, can. A lot of people don’t know this, but everything on the railroad is designed to fail safe. Putting things at its most restrictive state to protect train movement. Most of systems used on the railroad that are state of the art were designed in the 80s. The railroad its self doesn’t just install things that haven’t been tested because of how serious things can get if there are issues. Anyways, I’m going to watch more of your videos. Thanks!

[@LillianCrawfishDE]

When I was in college, I absolutely loved the process of learning. I felt like a sponge, just soaking everything up! I wanted to be a "perpetual student ", but it doesn't pay well. Now that I'm retired, I've found that I still have that craving for new knowledge. This channel does such a great job of "scratching that itch" for new knowledge in a way that is both interesting, entertaining, and presented in an easy-to-understand way, without feeling like I'm being talked down to. Thank you, Grady, for who you are and what you do!

[@Mesa_Mike]

I used to work for Safetran on the crossing controller and grade crossing predictor products. In general, the two approaches and the island are just one electrical circuit, not three, although there are more complex setups that might require more circuits, especially when there are multiple crossings with overlapping approaches. At the beginning of each approach, the tracks are shorted or, "shunted," usually with a filter that shorts the track only at specific AC frequency, This makes the track in each direction a big loop of wire (very thick wire!) that acts as an inductor to the electronics. An AC signal is transmitted onto the tracks via wires connected to the tracks on one side of the crossing, and wires leading to a receiver are connected to the tracks on the other side of the crossing. . When a train crosses the shunt going towards the crossing, the "loop of wire" gets shorter as the train approaches the crossing, causing phase and amplitude changes in the received signal. The electronics monitors the phase and amplitude of the received signal compared to the transmitted signal, and from this information can tell how close the train is to the crossing, how fast the train is going and whether it is approaching or leaving, or right on the crossing. The crossing warning equipment (lights, bells, gates) can be activated at an appropriate consistent time before the train arrives at the crossing, by predicting when the train will hit the crossing using the information of how far away it is and how fast it is going, The island is defined by the placement of the transmitter wires and the receiver wires on opposite sides of the crossing. When a train is on the island, there is no signal going to the receiver at all because the train provides a direct short of the transmitted signal between the transmitter and receiver. This is how the electronics knows there is a train on the island. After the train has passed the crossing, the "loop of wire" is now getting longer as the end of the train gets farther away. The electronics then knows it's safe to deactivate the crossing warning equipment. Also, if the train approaches a crossing and the warning equipment is activated, but then the train stops before getting to the crossing, the electronics can figure out that it is safe to deactivate the crossing warning equipment, so cars aren't waiting for a stopped train. Of course, it's been a while since I worked in the railroad equipment industry, so the technology of grade crossing predictors has probably changed a bit, but I imagine it's pretty much still the same as I described.

[@sptraxide]

Awesome description. You said it exactly how a signal maintainer explained it to me once. Thanks 👍

[@patrickvolk7031]

As a former US&S/Ansaldo, Bombardier, Siemens signal/onboard engineer, well said!

[@mattsbro92]

Yup this is modern day crossing prediction technology, what he's describing is what we call an "Easer-Weaser"

[@dsma2023]

This is the best description for how a good 90% of all crossings in the US work, with grade crossing predictors. The only "flaw" in the design of how a standard crossing like this works is that if there is a train on one side of the crossing in a approach, the crossing equipment is basically blind to a train on the other side past the point of where the first train is. To elaborate, if a crossing approach is divided into 10 sections on either side of the island, a train on one side at 30% of the approach will blind the equipment to see anything beyond 30% on the opposite side. A switching move, or train following another at short distance can cause a situation where the crossing predictors is unable to see that other movement, potentially causing a short warning time for vehicles. I always found this to be a fact that even not many maintainers completely understood when it comes to the circuits of a predictor.

[@BW-eu6pc]

Very nice work. I’m an electrical engineer and have designed wayside RR equipment for a couple of dozen years. I rarely write in anyone comment section, but it’s so entertaining to watch such a well made video with obvious attention to accuracy. Thanks!

[@tedfisk1211]

This is very good information. I am a lifelong railfan and I enjoy watching trains. When the crossing lights come on, I turn my vehicle off and enjoy watching the train pass. The explanation of the track circuits is one that I did not fully know prior to this video. Very good, Grady.

[@georgelawrence9308]

30+ years signal maintenance experience. This is the clearest explanation of crossing operation I have seen out side of a classroom.

[@marco23p]

Nice video! One thing I'd like to mention, though: your railway relay is not actually a "track relay". Track relays operate much like an old-fashioned electricity meter. They have an aluminium disc ("vane") that can rotate. To energise the relay, you need a local phase (like the voltage coil in an electricity meter) and a track phase, like the current coil in an electricity meter. They need to be in phase in order for the relay to attract. That way, only a certain voltage (one with both the correct frequency and phase) can attract the relay. If it's just a little bit off, it won't work. This whole thing is done in order to make the track relay insensitive to stray voltages, that happen to flow in the rails. Especially in electrified territory, where there are large traction currents. Edit: I understand now that these relays are used as track relays in some areas with DC track circuits. My apologies! I still like the technology of the vane relays I described though.

[@Pyth110]

That's true for AC track circuits. DC track circuits use the same types of relay he used.

[@dielangenase]

It's a form of relay that is used for the railway in the UK. Not the exact relay code we use for direct track circuitry from rails to relay, but close to it. As long as that relay sees voltage and allows it to energise or de-energises, it was very good as a way of showing how DC track circuits work in my opinion.

[@patrickvolk7031]

That is used in cab signaling as well. You have an interrupted signal (100Hz and 250Hz for old PRR) to give the next aspect. The faster, the faster (solid is an error). You don't need the vane relays on track circuits, just a frequency filter (it's a 1/0, where cab is like a percentage). The relay Grady had is what I know as a vital relay. It's used in track circuits, switch circuits, signal circuits, even for train control loops (onboard). Silver-impregnated carbon contacts (carbon doesn't spatter, silver for conductivity). The contacts are also designed to 'wipe', to prevent build-up of spatter. They all need to be calibrated every 4 years or so. There are often two coils to allow for redundancy (e.g. one control line fails, half the magnetic force is enough to close it). Track signals have to be distinct from cab signals, and you alternate frequencies which are not harmonics of each other, in the event you have a signal bleed over into the next circuit. You also have lots of timers. When you line a route through an interlocking, you have to keep it locked long enough for a train to go through it if it's close enough to the home signal to where it can't stop for a red (take the route away). Traffic uses stick relays (which look like an X, you reverse polarity to flip traffic).

[@pootispiker2866]

In the US, relays that are a hundred years old can still be found in daily signal operation because they absolutely must not fail in an unsafe condition. If they fail, they must fail in a way that turns the track signal to the most restricting aspect that it can display. The cheapest and most reliable way to accomplish this is through relays that open with gravity.

[@johnschultz9023]

marco 23p You're wrong. That's a Union Switch & Signal type b plug in relay.

[@TrainDude8901]

I'm a railfan in South Florida, and I am so upset that motorists and pedestrians down here are so impatient to wait for trains. I mean, I get it. Some people aren't used to the faster trains down here, but others think they can beat the train, when they can't. Amazing video!

[@kennethskirvin469]

Railroad preemption of traffic signals is a topic that could fill its own video. In its simplest form, a track clear function will flush vehicles that may be sitting on the tracks and it will prevent vehicles from turning onto the track-facing lanes during the "dwell" time. In more complicated forms, the intersection being preempted can communicate to other intersections, either through a central system or by peer-to-peer communication to change signal timings in the entire corridor to compensate for the additional volumes of detouring traffic.

[@HavasiP]

Where I drive trains, on the faster routes, the speed is measured at a point and of it's above a certain threshold the crossing will engage early. There's also built warning systems that detect if a vehicle is on the tracks while the crossing is engaged, a warning signal is then sent to the train driver at a certain point when it's plenty of time to stop before.

[@pootispiker2866]

You drive trains? How big is the steering wheel?

[@HavasiP]

@@pootispiker2866 About the same as in a regular car.

[@pootispiker2866]

​@@HavasiPSporty.

[@jimz4929]

I don’t think the model railroaders were cringing as much as you suggested. Arduino circuits are a very viable way to add this to ones model railroad. There are many others specifically built for model railroaders as well. Well done video!

In my country, Belgium, in 20 years, they removed 1/4 of the railroad crossing and added bridges or tunnels. It's nor always possible, but they did it a lot. It's quite impressive to see what they did in some cases, especially in places where roads are by the hill. Lots of digging and stabilisation took place.

[@ChristiaanHW]

they did that in The Netherlands to, and are still doing that. if it's possible separating road and rail traffic they do that, it takes years because of the amount of crossings. but separating the two is the safer option, if you remove the point where the two kinds of traffic cross you eliminate the possibility of a collision, and road traffic doesn't have to stop so traffic flows better which in turn safes people time and companies money. it's a win for everyone. unfortunately some crossings are surrounded by buildings and/or other infrastructure so sometimes it's (almost) impossible to put in a tunnel/underpass (the prefer tunnels over bridges).

[@HenryMidfields]

@@ChristiaanHW They've had a lot of at-grade crossings in Melbourne until the past few years ago when much of the rail has been relocated to viaducts.

[@SpudsMcCat]

depending on how often a train passes by and it's speed US communities replace at-grade crossings with bridges over or under. California is doing this for our "high speed" rail

[@Crazy_Caleb320]

Where I live (Near Taunton MA) trains do a unique pattern when signaling for a crossing. *Three Longs, One Short, and One Long* It’s mainly how CSX Locomotives signal through crossings. Not so much as the Purple Line (MBTA).

[@CyrusDemar]

Funny but true story. Just today I was driving with my 7 year old daughter, and driving past a railroad crossing she asked. "Dad? How do those work? How do they know trains are coming?" At the time I hadn't seen the video, but I am for sure going to watch it with my daughter this weekend. Thanks for the allways good work!

[@chrisharris7893]

Thank you for pointing out Distant Signal's channel. He has some of the best railfan vids out there. His knowledge and understanding seems to be above average.

[@laumuseka]

This train series is seriously so fascinating. I have always wondered how the signals were triggered, as soon as you started explaining it I was just blown away by the simplicity as well as reliability. Love it!

[@weirdmindofesh]

In my home town, there's a long street that paralells a rail line with a few intersections and somethings I noticed passing through that stretch regularly, when a train is present, all of the lights for the parallel road will change to green but turn arrows will be red and cross traffic can only turn right while a train is present. I also noticed that the light will react faster than the crossing arm. Each light has a high mounted white lamp that flashes when a train is approaching and flips to solid when the light changes over to this special state.

[@ianhayes5140]

Wow, you have really nailed this well. I'm a signalling engineer (we design/verify/validate grade crossings as they're considered part of the signalling system) and I don't think I could have explained it better than you have. One item though, track circuits detect the 'absence' of a train (because of exactly what you stated that there could be a train or there could be a failure so when it's energised that means no train) and axle counters (train detection devices that count axles and are widely used everywhere except USA it seems) detect the 'presence' of a train.

[@YoACC]

As a signal maintainer in Canada I appreciate you actually got the basics of this correct. Most videos I've seen usually the info is so so. Good video for giving the basics on how the system works

[@powdrhound-J]

Grady, as I am watching this video I am reminded of the day that I witnessed a railroad Speed Test. We drove up to a crossing, in the middle of Turlock, CA. A worker flagged us to a stop. We waited for a couple of minutes, then with a roar from the right an engine, pulling 2 or three special cars, goes flying by, leaving a huge cloud of dust billowing down the track. As they passed, the signals finally started to react. It was awesome. They had people at every crossing for miles up the Valley to conduct this test. They had just completed a rail replacement and leveling. If you could find and document such a speed test, I am sure you could make a great episode.

[@taliakuznetsova7092]

You actually made me realize I can when i'm able to set up my model trains again use this type of system for my crossings because you used the exact scale I used and type of track, if i have metal wheels. 3 rail O scale, also a great size to help us see.

[@sparkythebuilder]

An observation I have made is that when a train is passing through an intersection with a road, the horn will sound the entire time it is going through that intersection. How fast it is going doesn't matter. It will still sound the entire time even if it is moving very slowly. This is also the last horn blast.

[@killerbee.13]

that is definitely not the case here

[@ContinuedOak]

I’ve come to appreciate people who are train enthusiasts, I understand, it’s an amazingly complex system and a massive feat of engineering

[@bloqk16]

At grade crossings around Menlo Park, California, there are signs posted to advise people with emotional issues to phone an "800" number. It's a painfully sad commentary on the emotional stresses the youths in the US are experiencing, as a nearby high school had student incidents occurring on the railroad tracks.

[@Barbasnoo]

You are one of the most objectively likable people on the entire internet. Thank you for producing such incredible content. I learn so much every time I click one of your videos.

[@TheTrainMaster15]

Devastated to hear they don’t operate on magic

[@michaeltheaegis]

Lol, underrated comment.

[@FatDabFreddie]

😂😂😂😂

[@patrickbuick5459]

Sssh... he is hiding the fact that it is dwarves and such with their ears to the rails that activate the crossings....

[@piotrkol91]

Awesome video, I love everything rail related :) Here in Poland older railroad lines still to this day use actual rail workers on railroad crossings. There is literally a person stationed in a little hut next to the road and he has a lever to put the gates down and turn the lights on when a train is approaching. Usually he gets the info via a special phone line from nearby stations. Slowly but surely those kinds of crossing are being replaced with automated signals though. Used to have that kind of crossing near my home 5 years ago before it got replaced. There were several workers working in shifts, and I got to know most of them.

[@seiyaookami5190]

For me, I probably have less questions than most. I drove railroad crews around for a number of years and I asked questions. Most engineers had no issues answering questions. Unfortunately, I found out just how bad it is when someone ignores the arms. I got to take a crew home after a drunk lady got herself killed. The police told me that she had been pulled over for driving drunk 5 times and had lost her license after the second one. It shattered the emotions of the 23 year old conductor. I saw him crying for 3 hours as I drove him back to his home city. The 50 year old engineer was extremely depressed and look like he just wanted to give up. Please, never ignore those arms and never stop at a stop light such that there is any chance your car will be hit.

[@poohmaster54]

I am loving the railroad series! You should explore the 3 main types of railroads (Short line, Regional, and Class Is). You could also mention the evolution of locomotives from 500hp engines to the 6,000HP AC6000CW.

[@mooddyd86]

As a track engineer, I really appreciate this series bringing light to what we do on a daily basis. Keep up the great work, Grady!

[@aramilalpha1]

There is a large factory with a train yard a few hundred feet from the downtown in my city. Some locals get annoyed because the first grade crossing nearest the rail yard also happens to be one of the busiest four lane thoroughfares that crosses town. Unfortunately, the ire is at least justifiable in part because trains have been known to sit at this crossing for extended periods of time--30+ minutes is not nearly uncommon enough. Fortunately, due to the yard being so close, the trains usually block the crossings so it isn't easy or common for people to simply drive around the crossing arms. That being said, there are multiple crossings nearby and drivers have been known to simply drive a flew blocks down to a closed crossing in front of the train and drive around the arms. Also, perhaps due to their frequent use, about once every two or three months, one of the multiple crossings has some fault that causes the arms and bells to go on for hours and hours despite there being no train present. You'd think whoever is responsible for maintaining the rail crossing would have an interest in responding quickly, but they always seem to take their time. In either case, it seems like these are the best systems we have, but they sometimes strike me as deeply flawed. Like most such things, I'm sure its all about the economics and how much the railroads are willing to pay--at some point it's easier to pay off the families of a car full of dead people than it is to improve all grade crossings.

[@jovetj]

*Public Service Announcement: NEVER EVER drive around a lowered railroad crossing gate arm. It's ALWAYS illegal.* Even if you _think_ you can get away with it, don't do it. Trains are subject to the laws of physics, just like everything else. A big reason trains may need to stop for a while is if they are doing switching (or shunting). This means adding or removing cars from the train. Train main brakes are pneumatic (air-pressure driven), and are designed to apply at regular atmospheric pressure. To turn the brake off, pressure must be applied. There is usually one big long pressure line that runs from the start of the train to the end. When cars are added or removed from the train, it can take time to re-pressurize that air line so the train can move. It sounds like the only solution to those issues is grade separation (e.g. putting the road under or over the tracks). This costs millions of dollars, but it isn't even always possible if available space is at a premium.

[@frafraplanner9277]

Southeast Portland has this issue with dozens of level crossings being blocked by trains switching at Brooklyn Yard @@jovetj

[@liam3284]

Drivers seriously need to get used to not being first priority.

[@arandomyoutubechannel2940]

​@@liam3284 nope

[@crquality2002]

Very well done. As a railroad signalman who has watched several of your videos on other topics over the years, I found the terminology used and general understanding of the more complex systems to be perfect for the average person to understand without getting into the weeds of some of the caveats. Thank you for your efforts on this.

[@4RILDIGITAL]

Fascinating insights into the intricate engineering behind grade crossings. The balance between safety measures and trust from motorists is a critical aspect that I hadn't considered.

[@1121494]

There is in the video, however, a lack of accounting for the disregard for others, disregard for rules as well as plain utter idiocy of the average motorist.

[@pootispiker2866]

@@1121494 I don't think it needs said am any video that not respecting a train simply gets you killed

[@danlowe8684]

I worked on an Operation Lifesaver project back in the early 90s that performed RR x-ing upgrades at 300+ intersections. A couple more things: There is an advanced advisory sign that is round, yellow/black with RR X imprinted. There also is double yellow lines making it a no passing zone. And, at unsignalized crossings, a white reflective strip is attached facing approaching traffic from the opposite side of the tracks to give a 'strobe' effect when headlights it at night visible only in the gaps between the crossing train. Many crossing accidents are in rural areas at night without flashers wherein the vehicle slams into the side of a passing train.

[@skatedoof]

Great explanation of an "Easer wheezer" DC crossing. Constant warning (predictor) crossings can become extremely complicated when there are multiple routes to the crossing across many tracks. Then add to that the insulated joints necessary for control points. There can be several predictors running together to accurately determine the warning time.

[@bareth_]

Until watching this video, I really underestimated how advanced and complex railway crossings are. Awesome and very informative video!

[@piquat1]

Interesting opening. Having worked on a railroad there is SO MUCH based on how far you can see down the tracks if you're NOT on the train and instead are working trackside.

[@moneykingmm9298]

.

[@fiskurtjorn]

3:18 A few speedbumps make this crossing safer as cars need to slow down. 4:30 Way back in my school years A few kids figured out this system and did not know the difference between a train axle and a bike chain. Thus operating the gates.

[@LeveLUP.]

Sidenote: For the UK lots of Railroad (or Railway) Crossings are also controlled by a human signaller (usually the ones that have barriers on both sides) this increases the wait times because they have to be manually checked and then cleared for the train to cross. But also reduces the risk of someone getting stuck because there's usually a CCTV link directly to the signaller themselves. Automatic crossings do exist in the UK but are mostly being phased out because its a high risk area (according to Network rail - the UK's rail infrastructure goverment body) they're also doing some fancy stuff with Radar to figure out if a crossing is ocupied or not on some automatic level crossings.

[@Ink_25]

In Germany, we have experimented with radar "eggs" made by Honeywell placed next to level crossings. They were apparently not too reliable, so they're already being phased out again.

[@pootispiker2866]

I can just imagine how impractical that would be on a lot of shortlines in the US. It'd probably involve calling different houses in the area asking if they've seen a train. There's a LOT of dark territory in the US where trains run too infrequently for track signaling to make sense.

[@Tolono]

Here's how a modern AC track circuit detects the speed of the train: Leading from the bungalow, one wire connects to each rail. The computer measures the impedance between the two wires (AC resistance). If no train is present, the impedance is 100% (the wires/rails have little to no AC current going between them). As a train approaches and the circuit is shunted by the wheelsets (single piece of solid metal with an axle and two wheels) the AC current goes down one rail, through the first wheelset, and back down the other rail to the other wire, reducing the impedance. If a wheelset shunts directly where the wires connect, the impedance is 0%. The computer looks at the speed of the dropping impedance (AC resistance) so it knows when to lower the gates. As soon as the number starts increasing (or stops changing), it raises the gates. To keep the 100% value more stable, there is a place far away, farther away than you would ever need to detect a train, that has a "narrowband shunt" in the track. It's a filter connected across the rails that lets a specific AC frequency through and nothing else. If no train is present, the crossing sees this maximum distance instead which doesn't change. (If 100% was an open circuit, rain could drop the impedance and lower the gates). This system keeps the rail intact with no IJs (insulated joints) and allows nearby crossings to have completely separate overlapping circuits on different AC frequencies. Also, additional AC frequencies are used for the railroad signals that keep trains separated from each other (which inspired traffic signals (and improved our understanding of colored glass and color perception in general), but that's another story).

[@astramancer]

For non-powered low traffic grade crossings I like how england did it (and there's still some around). The bar is always down and you have to manually lift it by using a pneumatic pump(?). The pneumatic cylinder isn't perfectly sealed so it slowly loses pressure. It stays up long enough to get back in your car and drive through but not long enough that someone coming along later would have an open gate. It forces the driver to actually stop and listen for a train while giving them control over when to go. I imagine they're largely phased out because people with mobility issues can still drive.

[@nathanielcleland6566]

The most rustic I've ever encountered was on a bridleway in July. "Stop look listen beware of trains" and a manually operated gate. Also an instruction for horse riders to phone before crossing.

[@NewBuildmini]

There are plenty of older crossings with swing gates. In that case, drivers have to cross the tracks 5 times: once in the car, and 4 times on foot, to open and shut the gates. Definitely "safer" than having them cross only once. Speed bumps (or better yet, lowering the road before the LC so it acts as one) would've done a better job.

[@cynicalrabbit915]

One of my Uncles was a car guy. No duh! He worked for Fisher Body back in the 60s and early 70s before he retired. He told me about his encounter with a train. The crossing was passive. It also had a slight upward grade, so the tracks actually were higher than the road. He said the road was a bit slick that morning as it had a heavy layer of frost that had formed overnight. He admitted he'd been traveling a bit fast, and a train got to the crossing before he did. He pumped the brakes, the car slowed but didn't stop. The front of the car barely contacted the train. He was surprised that the front of the car didn't catch on the cars but was hit in a stataco manner.. Duh duh duh duh duh duh Until the car finally rolled backwards away from the train. He opened the driver's side door and got out to peruse the damage (he didn't tell me how bad it was ) , he shut the door after getting out looked at the front end, then went to get back and the door wouldn't open. He went to the passenger side door, but it wouldn't open either. This happened back in the 60s and the car he was driving, was a Cadillac, probably a mid 50s model. He was so Lucky that the car wasn't hooked by the train, dragged for yards and demolished, killing him in the process.

[@thezombiekillingcrew]

In the UK we use a combination of axle counter/track circuit and treadle units!

[@mlatpren]

Regarding trust as a safety feature: my hometown is a good example of what happens when you lose that trust. In my hometown, trains'll frequently stop _at_ the crossing during when school gets out, with roughly the centre of the train sitting on the island. It's a small town split in half along this single crossing, so all anyone can really do is wait. This has led to kids simply climbing the train, especially teens who need to get to work. Some have to go under, because they're not fit enough to climb the ladders (harder than it looks!). Now, trains start slowly, but that doesn't stop them from being dangerous once they start moving. Injuries _have_ happened. And now you also have cars trying to rush through when the gates close, lest they have to sit there for up to 30 minutes.

[@pootispiker2866]

The middle of trains don't start slowly. They could be completely stationary and jerk to several miles an hour with no warning.

[@perrylim9728]

I heard that in the UK, full barrier crossings are down for quite a long time because of the signalling system to guarantee the train's safety

[@jovetj]

Level crossings are often protected by the wayside signaling system in Europe. This means the train cannot get a clear signal to proceed until the line is clear AND the level crossings are protected. When trains move faster, the distance out ahead of the train for level crossings to activate increases. This often leads to 5-10+ minute wait times at level crossings. But, if there's a problem at a level crossing, the train will ultimately be forced to stop.

[@paulholmes672]

When stationed in East Anglia back in the late 70's, everything was station managed including manual gate crossings. I would be driving to or from work and if I saw across the fen, the station operator going towards the gate, I would go out of my way to stop so I could watch the flag gate process. With the commercialization of British Rail, that all went away (as well as reliable passenger rural train service!) Simpler times indeed.

[@cooperised]

Not just the train's safety, but the safety of other crossing users too. The signalling system will stop a train if the crossing does not close correctly. This does require a fair bit of lead time with large heavy trains, but crossing accidents here are rare. Sometimes the delay is minimal too, like in the common case of having a level crossing at the end of a station - the train is stopped or slowing anyway, so the crossing can close quite late.

[@perrylim9728]

@@cooperisedyeah. I am fortunate not to live in a country with level crossings. We put all of our trains either elevated or even better but most expensive, underground! For roads, we either elevate them or go underground.

[@stevenmiller279]

One of the things I remember when I was going through truck driving school, if we ever got a truck hung up or stalled out on the tracks, we should take a load lock bar and place it across the rails, which would alert operators to the present of something on the tracks there and hopefully stop an approaching train more quickly.

[@DomyTheMad420]

i actually already did a deep dive on our country's railroad crossings because i grew up near one that would close for 3-5 minutes for "no good reason". I tracked the issue down to the following hilarious problem after talking to a few local engineers and rail workers: they placed a set of sensors BEFORE the station that's within a stones throw. AS IN: a train would arrive in that station, and the crossing would close while people boarded & whatnot. and YES it has been explained by those same people that "we do this because cargo trains do not stop there". but i've also been told by those engineers they proposed cheap & effective fixes for the issue that'd prevent AMBULANCES getting stuck and save countless millions per year in lose earnings due to trafic jams. They were flat out ignored. :) Long live Belgium, the cuntry of "no no no we are modern. trust us. we are not a joke." edit: totally forgot to mention the fix that they're implementing after *40* years of citizens, employees or theirs & engineers complaining: The rail company is NOT doing the 5-15K technical fix on their sensors. the tax payer is going to pay for a few MILLION euro costing tunnel. > c u n t r y

[@JJGeneral1]

Amazing they just won’t install predictors that can tell train speed and determine when to lower gates. And will auto open when a train stops short of the crossing island.

[@jovetj]

Multi-minute warning/wait times are not uncommon in Europe at all.

[@NewBuildmini]

In the UK, these level crossings generally have a "non-stopping" and "stopping" mode, that's selected by the signaller depending on the train scheduled to pass. If "non-stopping" is selected, the crossing lowers as usual. If "stopping" is selected, the crossing does not lower on it's own. The train driver/guard has to press a button in a locked box before departing.

[@WackoMcGoose]

Can confirm the annoyance of "what train???" situations. Last month, I was stuck at a crossing for 15 minutes... because a BNSF truck (the kind with the drop-down wheels so it can drive on the tracks) was doing maintenance on the signal box, but in the process it was keeping the circuit triggered and the gates dropped, despite being fully out of the way of the road. ...although thinking about it, it might have been the maintenance itself keeping the crossing closed in the fail-safe state, rather than specifically the truck wheels closing the sensing circuit.

[@kaynicholls9066]

Here in Australia, more specifically the state of Victoria. Over the last 5 years our state government have been dismantling railway crossings & building sky rail stations instead, especially in the urban areas. The main reason was to prevent road congestion during peak hours when at times the crossings would be closed up to 30 minutes at a time. Another factor too was to reduce accidents & our road toll. 😊😊

[@EAFSQ9]

only in suburban Melbourne not in regional victoria

[@rex9412]

I live in WA and can't really say trains are something I can remember stopping for. I think it's mostly cause we have almost no trains. in Perth the only train I remember seeing in recent times which isn't saying much cause I don't go near any other train tracks much are the ones down south. they just go between each side of the freeway. I kinda wish we had more trains like to Exmouth a train would be super useful. a 12-16 hour trip from memory depending on what you're traveling in being 8 or less would make it not a multi day drive for most people.

[@matthewwilson4723]

@@rex9412 Perth has seen significant growth of it's rail network over the past 15 - 20 years, with more occurring now. There is a preference for grade separation - thereby avoiding creating new level crossings and removing existing ones. The level crossing removal project on the Dramadale line springs to mind.

[@dielaughing73]

​@@matthewwilson4723 indeed. That's "Armadale" for anyone not familiar with that area's reputation. Level (grade) crossing removal is a big part of the current city-wide MetroNet transit upgrades and has been happening on the Armadale and Midland Lines that I know of, possibly others. MetroNet also incorporates the new rail lines to the airport (completed), to Ellenbrook (underway) as well as the extension of the Armadale Line to Byford and the Joondalup Line to Yanchep. Unfortunately the various works to the Armadale Line will see it closed for the next 18 months.

[@rex9412]

@@matthewwilson4723 ah ok. yeah can't say I go out much as I'm mostly stuck to being in bed nowadays with some car trips rarely for appointments. Not surprising I'm wrong. I also think I'm not very observant for construction stuff cause it will change so not useful as a landmark for navigating I guess. IDK exactly something I developed as a kid to not get lost but not any actual thought behind what I notice/remember what's around me lol.

[@2112user]

Great video, as someone who used to build the work trucks the rail road uses to fix/build and mantain the rail, even I didn't know all of this. On the trucks we built, we installed "rail grear" that would alow a regular truck (small F150s to 12 wheen freightliners) to drive on the rail... then wire the trucks up to bypass the crossing signals with the flip of a switch. So the guys could work close to a crossing without setting off the crossing signals.

[@plunder1956]

In Britain's more squashed in network, with a greater population density and more frequent small roads crossing lines. We always tend to have automatic half gates at crossing points. We have several like that within 6 -15 miles of me. Most are TWO or even FOUR track locations, commonly found close to a railway station, with a footbridge across the tracks (great for photography). One very close to me has two scheduled trains every hour, just after each other in opposite directions. Which is superb for people who want th photograph trains, but annoying if you're sitting at a crossing waiting for the second one to arrive. Another benefit, for steam train fans, is the preserved Mid Hampshire railway. You can walk in on most days and see them, or even ride on them on special days. You would probably enjoy it. We do have a lot of historic engineering in Britian, together with many museums and historic collections and the many canals.

[@wraithcadmus]

If we let Grady in the NRM we'd not see him for a couple of days.

[@cubes123]

Road crossings usually also have dedicated telephones next to either side of the crossing that puts you straight through to the signalling people.

[@modelsteamers671]

Automatic barriers aren't allowed at 4 track locations.

[@NewBuildmini]

@@modelsteamers671 There used to be one in Floriston until 2006. It was 3 tracks.

[@kaseyklynstra2210]

Railroad signal design engineer (and railfan!) here: you did a pretty good job of getting the gist of everything. Railroad signaling is, as a whole (and by our own admission), a dark art with little available reference to the lay outsider. I've toyed around with the idea of making my own deep dives for everyone's benefit, but I'm also keenly aware it's not exactly a "hot" topic 😅. Couple notes: 5:05 - I suspect your power supply either is too low of voltage or too low of provided current, as this particular relay (Alstom/US&S A62-357) should "pick up" in a snap, not gently as shown. Hearing several layers of logic (at complex locations) sort themselves out in relays states is quite the experience. 7:42 - Relatedly, this model should be a "slow drop/release" relay, maintaining contact for a brief moment once coil power is removed -- that part seems to functioning properly. That said, track relays (when not using a microprocessor) are usually of the "slow pick" variety, so they don't recover the track circuit under a train with bad shunting, but will react immediately to a train's presence. With a microprocessor, we can implement any duration of Loss Of Shunt (LOS) delays, so we'll use standard relays for input. 7:22 - Fun fact: the flashing lights are controlled by gate position (gates being not up). If the gates lose their control signal and drop due to a cable break, etc., the lights should always come on as well. A dark crossing is worst-case scenario. 13:20 - Having been doing this for 8.5 years now, your explanation of crossing predictors is about as deep as I understand them to work too; it's a dark art on top of a dark art. Something about phase and resistance and inductance, but it's all consolidated into one device, so we really only concern ourselves with electrical connections, program selections, and track-circuit-length-to-frequency-selection dynamics. 13:30 - GCPs/HXPs (Grade Crossing Predictor/Highway Xing Predictor) do operate at "audio" frequencies, but unless something is very wrong, you'll never hear them. 13:40 - This will probably be covered more in a coming video, but we routinely overlay AC crossing frequencies with DC pulse coded track circuits (used with wayside signals) because each system can isolate the other signal type out. We actually have to filter the pulse coded circuits (begin my assumptions) to smooth out the high frequency harmonics of a square wave from interfering with crossing frequencies. 14:38 - Even if the police are already there and they say they've called in a blocked crossing to their dispatch, STILL CALL THE NUMBER and report it. The Amtrak crash in Michigan a few months ago was caused by a police miscommunication regarding which crossing was blocked and so their dispatch didn't contact Amtrak at all (they called CSX about a crossing miles away).

[@camerons.8322]

6:42 That fail-safe is really fun on a busy morning when it disables the turning signal at a traffic light. Talk about a traffic jam.

[@Train2589]

My brother, friend and I were watching trains along the KCS when we noticed a crossing was staying down with no train. Called the number on the blue plate and they had someone there within 30 minutes fixing it. That phone number is monitored 24/7 and is also for emergencies so they can attempt to stop any approaching trains.

[@DeadlyPlatypus]

I grew up around "passive-only" crossings. You get used to being careful around them, but quite a few people get killed because if they get to the crossing AFTER train does at NIGHT, it can be easy to assume there isn't a train until your headlights shine on it and it's too late to stop.

[@jovetj]

There has been a huge push in the last 20-40 years to get retroreflective visibility markers on the side of train cars to make them more visible on a crossing at night. Actually having street lights at crossings (on both sides) is also very important.

[@Cyberguy42]

Thanks for pointing this out, I hadn't considered the nighttime scenario of arriving to the crossing after the train.

[@pootispiker2866]

@@jovetjI've seen reflective strips on oil bombs before at a refinery I drive past. You can see them on the spur from miles away, they work great.

[@jovetj]

@@ithecastic Vehicles driving into the side of trains the driver cannot see at night has been a big problem since trains were invented. And moving trains are generally pretty quiet. Not that you'd hear that "clickety clack" as you're hundreds of feet from the crossing anyway.

[@Ink_25]

​@@ithecasticThere barely is any clickety-clack anymore, most track is continually welded

[@Hexagonaldonut]

I've seen an intersection + crossing combo where the oncoming light on the side of the crossing was doubled-up, so a light at the intersection proper and also at the crossing in addition to the crossing systems already there. Presumably it was intended as another layer to help avoid people stopping on the tracks.

[@kentslocum]

I'm loving this train series! My city is in the process of installing full-length crossing guards to block both directions of travel.

[@2alawabidingcitzen]

Never judge a book by its cover. I clicked this video like what can he tell me about railroad crossing in 17mins that I didn't know and learned a ton. Man you answered alot if questions I didn't know I had until seeing it and being like oooooooo that's what thats for.

[@Nielsblog]

In The Netherlands and presumably other European countries as well the number of tracks of a road road crossing is denoted multiple vertically stacked Saltires (crosses). Also nowadays almost all non-automated crossings got removed. Accidents still happen though, especially near train stations, primarily by inpatient drivers, cyclist and pedestrians.

[@ChristiaanHW]

in my city we used to have a crossing not even 50 meter from the local train station. this meant that whenever a train pulled into the station on the track approaching the crossing, the crossing would close. so you had to wait for the train to do it's business at the station and resume it way again, before the crossing would open up again. and with a station with a passenger train in either direction twice a hour and cargo trains that crossing was closed a lot (i think i read back then it was closed up to 20 minutes out of every hour) luckily a decade ago they redid the whole station area and now we have a tunnel for pedestrians, cyclist and motor vehicles, and no one has to wait for crossing trains anymore.

[@MikeV8652]

It should be mentioned that the mechanical or synthesized bell sound emitted from crossing signals is often low in volume and ceases as soon as the gate is down. Its purpose is not to alert drivers in closed cars with the radio going, but rather is to alert pedestrians that crossing gates are descending from above.

[@goatsplitter]

I will fully admit, that I could not possibly care less about trains. But I am always fascinated by your topics and discussions on the engineering aspects of train stuff. I've watched so many train related engineering videos of yours and they're all fascinating. Not because its train content, but because of how you present the information. You make the topic fun and informative. Thank you!

[@captainevenslower4400]

In my part of Europe Austria there are almost never any audible warnings at train crossings. The locomotives don't have any bells or flashing lights, there are no bells at most of the crossings, and trains only use thier horn on crossings without any barriers. The barriers also often only have a single stop light. Yet I would argue that accidents are also quite rare.

[@johnwiley8417]

I watched on Nebula, but dropped in on KZbin to give a thumbs up and comment. I've been an Amateur Radio (Ham radio) operator for more than thirty years, a broadcast engineer for twenty years before retirement, and an electronics geek for more than fifty-five years. That's the slowest relay I've ever seen! It doesn't seem to have a retarding mechanism. Why is it so slow? Great content, Grady!

[@jovetj]

It's slow so errant rapid control changes don't affect it.

[@SkyhawkSteve]

good question... I wouldn't mind learning about the details of that relay too.

[@Teqnyq]

A mechanical schmitt trigger

[@jovetj]

@@SkyhawkSteve What would you like to know? It's a very simple relay. Railroads have employed much more complicated relays than that one.

[@johnwiley8417]

@@jovetj I misphrased my question. What makes it so slow?

[@dougdow1287]

I have a friend whose Great Grandfather invented the Morrison Crossing, the first electrically activated crossing warning system. :)

[@KeaganZeile]

I’ve really been enjoying this series. Great learning!

[@corriegillett2536]

Sig tech in Australia here, you nailed it Grady!! Thank you for being so precise.

[@jackprier7727]

Thanks again for the excellent demos, Grady--your Public counts on you for keeping this all fun-

[@Pribumi1]

In my country we don't have problems discussed in the video because most grade crossings are human controlled. Some controlled from the station headmaster but rest are controlled by post on the crossing. For detecting train, we have automatic sensors and those are relayed to the stations or controller hub of the entire operation and relayed to the dedicated post via bell signal.

[@ronbennett7885]

Most common mistake I see at crossings is drivers ignoring the flashing red lights and relying on the gates alone. In some instances, the gates may start going up despite another train approaching from the other direction. In short, RRs should better educate drivers that the red lights alone are the warning. Not relying on gates whether it's safe or not to cross.

[@TimChuma]

Reminds me of a video about a runaway suburban service that was longer than the train running without brakes or a driver from the end of the line to major train station in the city where they redirected it into a diesel. The diesel locomotive got off fine from that exchange. They eventually fixed the suburban train and it served the rest of its life.

[@Marconius6]

You mentioned that the crossbuck is an international sign, which is technically true, but it's worth noting the American way of doing it with lots of text on it is pretty region/country specific. Most countries use a simple white cross (usually one more elongated horizontally, not square like the American one), with a red outline, no text at all. Though there's apparently quite a bit of regional variation: en.wikipedia.org/wiki/Crossbuck

[@dawakat08]

I work as an electrician for the ground drinking water systems here in Houston and I drive all over the Houston area to various well and water storage facilities. I really enjoy this channel because it teaches me something new and relatable to my job every week it seems like lol, whether it's water effects of erosion or train tracks which the city has miles of miles of tracks for the petrochemical industry which I came from.

[@MeriaDuck]

Glad that in our very dense country with the most complex railroad network of the world, we do not have the honk-the-horn requirement for each crossing here in the Netherlands. That would be VERY annoying.

[@RemcovanZuijlen]

I was thinking the same thing. Especially if you live near a railroad, which could be quite common in NL especially in the 'Randstad'.