Speaker 1: Brought to you by the reinvented two thousand twelve camera.
Speaker 1: It's ready. Are you get in touch with technology with
Speaker 1: tech stuff from how stuff works dot com. Hello, everyone,
Speaker 1: welcome to tech stuff. My name is Chris Poulette and
Speaker 1: I am an editor at how stuff works dot com.
Speaker 1: Sitting across from me is senior writer Jonathan Strickland. I
Speaker 1: hear that train of coming. It's coming around the bend.
Speaker 1: So did you engineer that quote? No, actually I did
Speaker 1: not engineer that. That was That was something conducted by
Speaker 1: someone else. That was such a terrible stretch. But you
Speaker 1: know what, I'm gonna save myself here by going into
Speaker 1: a little listener mail. This listener mail comes from Weston,
Speaker 1: who says, Hi, my name is Weston. Well I know Weston.
Speaker 1: I just said that I'm from South Carolina and looking
Speaker 1: through your white extensive list of podcasts, I could not
Speaker 1: find one that involved how railroad crossing signals work. So
Speaker 1: I was wondering if you could explain that, and if
Speaker 1: you could explain how railroad crossing systems tie into traffic
Speaker 1: signals in more urban districts. Thanks a lot, keep doing
Speaker 1: your thing. Well, thanks Weston. Yes it is true. We
Speaker 1: had not done a podcast on railroad crossing signals. Uh,
Speaker 1: it just never honestly occurred to me, and in fact,
Speaker 1: until I started researching this, I had no idea how
Speaker 1: complicated it really was. That's true, although they have changed
Speaker 1: over the years too to some degree. Yeah, it used
Speaker 1: to be that the railroad crossing signal was that the
Speaker 1: train in very busy areas, the train would come to
Speaker 1: a stop. A flag man would go to the crossing
Speaker 1: area and and manually stop traffic for the train to
Speaker 1: pass through, and then would go jog get back on
Speaker 1: the train and then everything would start up again. So
Speaker 1: that's about you know, that's pretty simple technology. Yeah, have
Speaker 1: to agree that that's uh well, there's not a lot
Speaker 1: of electronic technology involved in that. At night, sometimes they'd
Speaker 1: use flares. I've actually seen that. I've there was a
Speaker 1: rural crossing, a railroad crossing in northern Georgia, which is
Speaker 1: where I grew up. What you can tell because of
Speaker 1: my deep Southern accent, But in in rural Georgia there
Speaker 1: was a crossing at one point. I remember as a
Speaker 1: kid we came up to it, and I think the
Speaker 1: reason for using the flares was not because there was
Speaker 1: no modern crossing signal there. I think the modern crossing
Speaker 1: signal was unfortunately out of order, and so they were
Speaker 1: using the flares as a backup system and UH, and
Speaker 1: that's exactly what they did. They stopped the train, a
Speaker 1: guy got out and lit some flares along the side
Speaker 1: of the tracks, and then the train went through and
Speaker 1: we had to wait, and then we drove on by.
Speaker 1: Well then it actually seems like it could be a
Speaker 1: little bit more reliable than some of the technology that
Speaker 1: we we're researching. UM. I have to have to give
Speaker 1: any shout out actually to uh matt Enus who has
Speaker 1: a really awesome website about the electronics behind railroad crossing
Speaker 1: signal technology and it's it's very very through. Apparently he
Speaker 1: really likes electronics and trains, so this was sort of
Speaker 1: a natural for him. Yeah, you can find his his
Speaker 1: website at Matt dot z o n T dot org.
Speaker 1: I thought i'd give a shout out because I also
Speaker 1: found it really helpful. He has lots of of of
Speaker 1: technical drawings for for circuitry as well as some great animations.
Speaker 1: It really makes understanding this UH a lot easier, although
Speaker 1: again it's still a very when you get if you
Speaker 1: really dig down, it's still really complicated. Well A said it.
Speaker 1: As it turns out, just about every type of signal
Speaker 1: UH crossing signal uses some form of an electronic relay
Speaker 1: or I should say electrical relay. Um. And a lot
Speaker 1: of it has to do with basically detecting that a
Speaker 1: train is coming. Now it's not necessarily from a distance.
Speaker 1: In a lot of cases, it's basically when it's right
Speaker 1: on top of the crossing, not literally right now, when
Speaker 1: when it's right there at the crossing before it gets
Speaker 1: to the uh for it actually gets to the intersection
Speaker 1: with a roadway. Yeah. Yeah, so there are some there
Speaker 1: are lots of different types of these these systems, we
Speaker 1: should say, because first of all, uh, it's it's easy
Speaker 1: to forget that the railroad system is not a unified
Speaker 1: thing overseen by a single entity. No, that's correct. There
Speaker 1: are several railroad systems throughout the United States alone, and
Speaker 1: you know that's just the United States where you know,
Speaker 1: it gets way more complicated when you're looking at things
Speaker 1: like international railroad systems that go through most of Europe
Speaker 1: for example. UM. So, because there are all these different
Speaker 1: entities that are running the railroads, I mean there are
Speaker 1: are certain standards, like railroads are railroad rails are at
Speaker 1: a standard with where else your trains cannot go from
Speaker 1: one system to another. But things like the signaling systems
Speaker 1: the electronics they use are not necessarily standard across the board.
Speaker 1: They're all supposed to operate in a standard way, but
Speaker 1: the way you get there is not necessarily standard. If
Speaker 1: that makes sense. Well, what I thought we might do
Speaker 1: is actually talk about the signals themselves, and then we
Speaker 1: could talk about the way that they're triggered me because um,
Speaker 1: you know, and at a given intersection. Actually, that's that's
Speaker 1: another good point back to what you just said, was
Speaker 1: um that not every signal, uh, not every crossing has
Speaker 1: the same types of signals either, even on the same uh,
Speaker 1: even on the same railroad. So you know a lot
Speaker 1: of times you'll see you know, the signal mast, which
Speaker 1: is that poll with the lights on either side of it. Hum.
Speaker 1: And basically this is just a current flowing through, just
Speaker 1: like you would with a typical light bulb. Um, but
Speaker 1: it's it's got a relay, a flasher relay between that
Speaker 1: basically alternates the circuits. So one light goes on the
Speaker 1: other one goes off. Then they switch back and forth,
Speaker 1: back and forth. Yeah, I think it pretty easy. Think
Speaker 1: of the flasher relay is kind of like a switch
Speaker 1: that opens and closes, but when it when it when
Speaker 1: it opens for one side, it's closed for the other
Speaker 1: and vice versa. So as long as power is running
Speaker 1: through this, one side of the lights will light up
Speaker 1: and the other side will remain dark. And it alternates,
Speaker 1: and that's what creates the flashing pattern. And they alternated.
Speaker 1: There's one way that it can be alternated. Again. There
Speaker 1: are lots of systems, but one way that they can
Speaker 1: alternate is through using electromagnets. Our old friend, the electromagnets, right,
Speaker 1: So the electro magnets will have a set of coils
Speaker 1: on either side, and when one set of coils gets power,
Speaker 1: that pulls the switch to that side and creates a
Speaker 1: magnetic field which pulls the switch her. That's what lights
Speaker 1: up the lights on one side, and then the other
Speaker 1: set of coils will get power. The first set will
Speaker 1: lose power, so now the switch will be pulled back
Speaker 1: to the other side, which will light up the other
Speaker 1: side of the lights. And alternating this back and forth
Speaker 1: is what gives you that click click click click as
Speaker 1: the as the flashers go on and off. Uh. I
Speaker 1: will have to say, though, that this behavior changes dramatically
Speaker 1: if you happen to be within a certain distance of UFOs,
Speaker 1: as seen in the documentary but nothing but Close Encounters
Speaker 1: of the Third Kind? Man, did you not watch it?
Speaker 1: I mean those lights went crazy. This means something, This
Speaker 1: is important. Okay, that was That was clearly a joke.
Speaker 1: I was referencing a Spielberg movie, Close Encounters of the
Speaker 1: Third Kind. I do not, in fact believe that aliens
Speaker 1: affect our railroad crossings at some too busy messine with
Speaker 1: our fast food restaurants. At some point we should uh
Speaker 1: do a podcast on why every time aliens come down
Speaker 1: your radio dial changes and the rail road You're always
Speaker 1: near a railroad. You know what drives me stuff podcast?
Speaker 1: I'm listening to the radio and next thing, you know,
Speaker 1: aliens come down and it switches the golden oldies. I
Speaker 1: just hate that. Um And we got a little off
Speaker 1: track on our railroad podcast speaking speaking of electromagnets, so
Speaker 1: that the same the same uh things sort of applies
Speaker 1: to the bell. The bell that goes clian client client clang,
Speaker 1: that tells you that's going on, except, um, what's going
Speaker 1: on there is the electromagnet is pushing the clapper to
Speaker 1: the bell. The clapper is the thing. If you're not
Speaker 1: familiar with bell technology, and I'm not talking about mob bell,
Speaker 1: it's got the il communication. Um, you got the clapper
Speaker 1: being pushed to the side of the bell by an electromagnet.
Speaker 1: But the thing is the thing. I thought it was
Speaker 1: cool about this at least according to to Matt's page.
Speaker 1: Is what happens is once the clapper reaches the bell,
Speaker 1: it's breaking the connection uh to the electrone, so it
Speaker 1: pulls it back and it pushes it back again. So
Speaker 1: it's just snapping back and forth. It's the momentum that
Speaker 1: carries it forward so that it actually makes contact with
Speaker 1: the bell. Yes, and then it gets pulled back to
Speaker 1: its original position where again where and then it gets
Speaker 1: pushed again. Yeah and yeah, that's kind of that's pretty neat.
Speaker 1: And of course it's happening at a regular interval because
Speaker 1: of the the length I guess of the piece, the
Speaker 1: physical clapper piece. It's it's a centrical same same principle
Speaker 1: that you'll find on other alarm bells, things like you
Speaker 1: know the classic fire station alarm bell works on the
Speaker 1: same principle. I'm sorry that kind of alarms me. Yeah,
Speaker 1: well I live right next to a fire station, so
Speaker 1: really familiar with the fire station bell. Okay. So the
Speaker 1: gates that drop down in front of the uh the crossing,
Speaker 1: you know, the red and white bars basically if that,
Speaker 1: sometimes have lights on them. Sometimes I don't. UM, they
Speaker 1: use a different kind of technology. They actually use a
Speaker 1: motor UM and there's a relay called the motor control
Speaker 1: relay that basically allows the the motor to operate in
Speaker 1: one direction as the gate comes down. So basically it
Speaker 1: is starting to push the gate down and at a
Speaker 1: certain point, of course, you know, there's a weight on
Speaker 1: the other end to counterbalance and um, at a certain
Speaker 1: point the gate would come crashing down, so about midway
Speaker 1: down or so, the relay switches the motor to prevent
Speaker 1: it from the gate from crashing down too quickly. So
Speaker 1: on what you know, at the beginning, it's starting it
Speaker 1: down and then the bottom is like oh okay, okay, okay,
Speaker 1: not too fast, not too fast, all right, there you go.
Speaker 1: So yeah, so in one case it's actually pushing it downward,
Speaker 1: and in the other case, it's pushing upward, but not
Speaker 1: so hard that it makes the gate go right back
Speaker 1: up again, right, and just slows the gates decent. Yeah.
Speaker 1: And and of course there are many ways to achieve
Speaker 1: this effect. Apparently it has to do with the manufacturer
Speaker 1: of the gear. Um, at least according to Matt, it's
Speaker 1: really useful railroad signal technology page. Yeah. And and the
Speaker 1: reason you don't want those gates coming down too quickly,
Speaker 1: I mean, apart from the fact that it's gonna cause
Speaker 1: way too much wear and tear in your equipment, is
Speaker 1: that you don't want to whack cars that are in
Speaker 1: the the the railroad area when the signal is activated.
Speaker 1: You know, you have to have enough time for the
Speaker 1: car to clear. Um. That's also that's really the chief
Speaker 1: reason for the bell. The bell is really there to
Speaker 1: let people know people who are on the tracks at
Speaker 1: that moment as they're crossing over, that hey, there's a
Speaker 1: train in coming, your best get some moving. But that
Speaker 1: they use the bell ringing noise because they found that
Speaker 1: having an old guy send and they're yelling that out
Speaker 1: just wasn't nearly as effective. Yeah. Yeah, it's um one
Speaker 1: of those things that people still try to circumvent quite
Speaker 1: frequently terrible, terrible idea. It's a very very bad idea
Speaker 1: to try to drive around the gates um or you know,
Speaker 1: if you have to be any crossing, like there is
Speaker 1: one near my house, Um, people often go through and
Speaker 1: sit there on the track waiting for the light change.
Speaker 1: And that's just a bad idea. Yeah, you don't want
Speaker 1: to be there. There are stories I could tell, but
Speaker 1: I won't, but yeah, it's just a bad idea. So
Speaker 1: that got that. That covers the UH the basics of
Speaker 1: the arms and the mast, yeah, and the lights that
Speaker 1: in the so and the these this system. By the way,
Speaker 1: you asked Weston specifically about how that works within urban areas.
Speaker 1: The system can be keyed into any adjacent UH traffic signal. Essentially,
Speaker 1: it's just part of that traffic signals cycle. So if
Speaker 1: the traffic signal receives UM signal from the railroad crossing
Speaker 1: its superseds, anything else on that intersection, so instead of
Speaker 1: the lights cycling through as they normally would, it'll be
Speaker 1: stuck on a particular setting. So maybe like the parallel
Speaker 1: road would still get green, but the road that would
Speaker 1: intersect would have a red until the until the signal
Speaker 1: from the railroad crossing gave the all clear. Yes, that's
Speaker 1: that's exactly how it works. At the crossing near my house.
Speaker 1: It blocks out all the traffic that would necessarily cross.
Speaker 1: And the thing is, I've I've seen cars unfortunately who
Speaker 1: uh not unfortunately in the other sense we were speaking
Speaker 1: of earlier, the ones who get there at the red
Speaker 1: light waiting to cross. There's there are basically two sets
Speaker 1: of there's two roads, one on either side of the
Speaker 1: tracks parallel to it, and they'll go and they'll wait
Speaker 1: on that red light and then the gates will come down.
Speaker 1: They're going, Ah, you gotta be kidding me. I mean,
Speaker 1: there's a train coming and now I have to wait
Speaker 1: through this. Yeah, this was gonna be maybe a min
Speaker 1: and a half way, and now I'm looking at upwards
Speaker 1: of three to ten minutes just fitting on the train.
Speaker 1: I gotta say, though, I did have that happen to
Speaker 1: me not that long ago, but it ended up being
Speaker 1: a thing as opposed to a bad thing, because it
Speaker 1: was a circus train. It was actually really cool. That's yeah,
Speaker 1: um Dumbo waved, Okay, Well, actually that's that. This is
Speaker 1: where it stops being quite so simple to explain, because
Speaker 1: those are the signals. But triggering the signals, that's that's
Speaker 1: a little more more tricky. Let's let's talk in a
Speaker 1: really high level way, because if you dig down, it
Speaker 1: just gets to the point where you really need a
Speaker 1: good I was about, say, grounding a good understanding of
Speaker 1: electrical engineering in order to uh, to really follow and
Speaker 1: because probably I would guess most of our audience doesn't
Speaker 1: have that necessarily. I'm sure there's some of you who do,
Speaker 1: but I think the general audience probably doesn't. It would
Speaker 1: just be it would be torturous for us to try
Speaker 1: and walk through it. Yeah, I'm not sure that I
Speaker 1: have the the basics down enough. Sure I don't have
Speaker 1: the basics down, but we can talk a little bit
Speaker 1: about it from a high level. Um that virtually any
Speaker 1: of the crossings that have electronic signals, you're gonna see
Speaker 1: one of those boxes like you would see at a
Speaker 1: at an intersection in an urban environment that has a
Speaker 1: series of relays and basically a couple of batteries in it.
Speaker 1: You might say, why does it need the batteries? Well, Um,
Speaker 1: the tracks around the railroad crossing have a circuit in
Speaker 1: them that helps control the railroad crossing signals. Yeah, let's
Speaker 1: to kind of give it a basic set, all right.
Speaker 1: Imagine that you have a stretch of railroad track, okay,
Speaker 1: and that you are approaching You're you're walking along the
Speaker 1: railroad track, and you're you're gradually getting to a point
Speaker 1: where the railroad is going to intersect with a road. Now,
Speaker 1: as you're walking along that track, you will eventually come
Speaker 1: to a point where there will be a special insulator
Speaker 1: block that is on each rail. Now, this insulator block,
Speaker 1: the whole reason for this is to allow there to
Speaker 1: be a circuit along a stretch of track. If you
Speaker 1: didn't have that insulator block there, the the electricity would
Speaker 1: just flow through the entire track and just disperse essentially
Speaker 1: because you would have like the world's biggest circuit. So
Speaker 1: you have to block it off. Yeah, and this is
Speaker 1: not the kind of charge like you'd see on light rail, um,
Speaker 1: you know the third rail. Yeah, this is not to
Speaker 1: provide power to the train at all. No, No, it's
Speaker 1: just detection system. Yeah exactly. So you've got you've got
Speaker 1: these insulators, that's what blocks the electric signal from continuing through. Uh,
Speaker 1: You've got and you have relays connecting the two tracks together,
Speaker 1: and you constantly have a low level of power going
Speaker 1: through this this basic circuit all right. Now, Uh, there's
Speaker 1: usually another insulator block somewhere near where the actual road intersects,
Speaker 1: and then you have a second set of circuits on
Speaker 1: the other side and in its most basic form. And
Speaker 1: the reason for that is so that you can detect
Speaker 1: when the train passes from one one part of the
Speaker 1: track to another part. And that's important because eventually you're
Speaker 1: gonna have to have these signals stop signaling. You have
Speaker 1: to have something that tells the electronics, Hey, the train's gone,
Speaker 1: turn off the flashers, turn off the bell, and lift
Speaker 1: the gates. Yes. He As a matter of fact, the
Speaker 1: the part of the track approaching an intersection is called
Speaker 1: the approach yes, which by the way, is not always
Speaker 1: the same side because trains, because some tracks will allow
Speaker 1: trains that travel in either direction, So the approach is
Speaker 1: completely dependent upon the direction the train is coming from
Speaker 1: at any particular time. So the approach side will change
Speaker 1: depending on the where the trains coming from. Um. Now,
Speaker 1: when a train crosses over the insulator and hits the
Speaker 1: section of track where you've got that circuit, the trains
Speaker 1: wheels are steel. The axle connecting the wheels are steel.
Speaker 1: This massive amount of steel when it makes contact with
Speaker 1: the tracks creates a short circuit, which means that it's
Speaker 1: it's it's pulling the power, so it's no longer going
Speaker 1: through the relay like it normally what it's going through
Speaker 1: the axle instead, and that's what is That's what creates
Speaker 1: the the alert for the signaling system that hey, there's
Speaker 1: a train coming. Now. There are other problems with this, yes,
Speaker 1: one of the big ones is that this does not
Speaker 1: tell we're acting like this is all like you know,
Speaker 1: they're all coherent and cognitive. It's not. But this does
Speaker 1: not indicate how fast that train is moving, just that
Speaker 1: there is a short circuit, and therefore the signal should
Speaker 1: go off right. So you have a couple of different
Speaker 1: things you have to take into consideration there. One is,
Speaker 1: are all the trains that are traveling on this track
Speaker 1: generally going to be moving at the same speed. If
Speaker 1: they are, that makes this problem way easier to solve,
Speaker 1: because what the problem is you need to figure out
Speaker 1: how long from the moment that this short circuit happens,
Speaker 1: should the signals. What's the time delay between when the
Speaker 1: short circuit happens and when the signals activate, right, because
Speaker 1: if the train is too far back and the signals activate,
Speaker 1: you you take everybody off because they're like, well, look,
Speaker 1: the gate came down and I've been waiting here for
Speaker 1: for fifteen seconds and I still don't see a train.
Speaker 1: I'm just gonna go, and that's going to cause a problem. Um.
Speaker 1: In other cases, you may have a train this moving
Speaker 1: so quickly that when it triggers the short circuit, it
Speaker 1: actually reaches the intersection before the signals go off, so
Speaker 1: you have to take that into account. Now, if all
Speaker 1: the trains are moving at the same speed, you just
Speaker 1: figure the right distance from the crossing and you install
Speaker 1: everything that way, and then there's no problem relatively speaking,
Speaker 1: because the trains are always going to hit the intersection
Speaker 1: at around the same time, so you can time it
Speaker 1: out that way. If the trains are gonna be moving
Speaker 1: at different speeds, then you have to figure out, okay, well,
Speaker 1: how do I indicate how fast this train is going.
Speaker 1: You can either fudget where you kind of take an
Speaker 1: average speed of all the trains that tend to go
Speaker 1: across that track, or you can pick the trains that
Speaker 1: are the most common, like the ones that are are
Speaker 1: usually on that track or that travel through there during
Speaker 1: high traffic areas and use that speed. Or you can
Speaker 1: install sensors that actually do indicate you know how fast
Speaker 1: the train is going and then send that information to
Speaker 1: the control system to alert it when it should initiate
Speaker 1: the warning. So those are your various options. But yeah,
Speaker 1: that's it's all about short circuiting, which is kind of
Speaker 1: cool because when you think about it, you know, the
Speaker 1: connotation of the term short circuit has usually a fairly
Speaker 1: negative feel to it, right, you know, you know, you
Speaker 1: normally don't want things to short circuit unless you're Johnny
Speaker 1: five nice. Yeah, I like that. I figured I had
Speaker 1: to work that in there. Well, he was alive, he
Speaker 1: was theoretically, Um, So the thing is you have so
Speaker 1: that that's basically how it knows it's coming. The question
Speaker 1: is how the crossing signal UH is notified when the
Speaker 1: train is gone. And so basically there are are two
Speaker 1: sets of tracks there too, since there are two approaches,
Speaker 1: because theoretically, if a train could come from either direction,
Speaker 1: you would want that anyway, but you also need the
Speaker 1: other approach to to notify it too. Because um, as
Speaker 1: the train passes from one side of the crossing to
Speaker 1: the other, there is another uh, there's another circuit too short.
Speaker 1: And when both sets of circuits are therefore untriggered anymore,
Speaker 1: that means, well, the train has come and gone, and
Speaker 1: those signals can you know, the the arms go back
Speaker 1: up and the lights go back off, and the bell
Speaker 1: stops clanging most of the time, but there are problems
Speaker 1: with it it you know, those of you who live
Speaker 1: near railroad tracks and have seen trains do this annoying behavior.
Speaker 1: Um because of course they probably have to. There are
Speaker 1: reasons why they have to. But for the driver it's
Speaker 1: kind of annoying to sit there and watch a train
Speaker 1: stop and then back up a little bit, and you're going,
Speaker 1: how long do I have to wait? Well, that does
Speaker 1: happen from time to time. They're there, you know, traffic
Speaker 1: issues to be considered. And the thing is the relays
Speaker 1: aren't exactly endowed with a lot of artificial intelligence. They
Speaker 1: they're either on or they're off right, And there are
Speaker 1: times when a track, a train can pass through an
Speaker 1: intersection and then it has to back up for traffic
Speaker 1: reasons a little bit, and that triggers the signal again,
Speaker 1: and then when it leaves, it's you know, there, there's
Speaker 1: it can it can trip the signal to a point
Speaker 1: where the next train that comes from from uh, you know,
Speaker 1: I'm not sure if it comes from that direction from
Speaker 1: where the train left, but it may not necessarily trip
Speaker 1: the signal because of the way it's wired. So what
Speaker 1: you're saying is that that because the train activated the
Speaker 1: signal the first time, then reactivated it without crossing over
Speaker 1: into the opposite side. Uh, you've got a faulty system.
Speaker 1: That's how I would have said it if I were
Speaker 1: more eloquent. Well, like I had the opportunity to really
Speaker 1: think about it and listen to what you were saying.
Speaker 1: So that was that was It's not that I'm it's
Speaker 1: not that I'm pithy or anything. I just had more time. Um. Yeah,
Speaker 1: there is a problem. There are some ways around that.
Speaker 1: One is to create a kind of a failsafe system
Speaker 1: where you add a third set of a third circuit
Speaker 1: two circuit system, because remember we've got we've got the
Speaker 1: side that the trains coming from and the side that
Speaker 1: the train is going to. Uh, and usually that that
Speaker 1: ends up having a break right at where the cross
Speaker 1: is um and when usually normal in normal operation, as
Speaker 1: one side gets activated and the other side becomes unactivated. Uh.
Speaker 1: You that that's when it says, okay, well the train
Speaker 1: has passed from this one side, we can now raise
Speaker 1: the gates and turn off the lights and all this
Speaker 1: kind of stuff. If you add a third section that's
Speaker 1: directly over where the road crosses over, uh, and then
Speaker 1: you you create that that can give you that extra
Speaker 1: set of circuits there that will allow you to either
Speaker 1: switch something off if the train does have to stop
Speaker 1: and back up, or more importantly, I think there is
Speaker 1: the chance that let's say the train has passed over
Speaker 1: the the first the approach. Okay, so the end of
Speaker 1: the train has left the approach, there's no longer any
Speaker 1: contact there where it will create a short circuit. But
Speaker 1: the train has not left the other side yet, It
Speaker 1: hasn't gone through, and then it starts to back up.
Speaker 1: You may have gotten to the point where the warning
Speaker 1: systems have shut off and the gates have gone up,
Speaker 1: but the train is still approaching that intersection. Right. That's
Speaker 1: also dangerous because everyone thinks, oh, I can go through
Speaker 1: now because the gates went up, the lights are off,
Speaker 1: the bell is no longer ringing, but it's because that
Speaker 1: the the full circuit hasn't been tripped yet, so the
Speaker 1: train starts backing up and you are possibly endangered. Adding
Speaker 1: this third circuit, where you have a section of track
Speaker 1: in the center between the approach and the departure area,
Speaker 1: allows you to create a fail safe. So some crossings
Speaker 1: do have this, some don't. It all depends on when
Speaker 1: it was built and the last time that it was
Speaker 1: fixed really adjusted. It's called an island, yes, the section
Speaker 1: that is directly over the road, and apparently it does
Speaker 1: have there. There are some certain reasons why you want
Speaker 1: it to be an island that goes over both sides,
Speaker 1: because if you have the insulators or anything like that
Speaker 1: built into the road itself, the thickness that the road
Speaker 1: can actually affect the way the signal is tripped, so
Speaker 1: you really have to uh really have to leave the
Speaker 1: rails that crossed the road. I thought that was kind
Speaker 1: of interesting actually, because I was I was thinking as
Speaker 1: I started reading um reading up on it, I thought,
Speaker 1: you know, when I go home, I'm gonna look and
Speaker 1: see where the the insulators are that that split the
Speaker 1: two approaches. And then as I started reading about it,
Speaker 1: you know, it dawned to me. Yes, I mean, if
Speaker 1: they have to repave the road or something like that,
Speaker 1: it's going to affect that. And if the train rolls
Speaker 1: over um that and can't actually you know, it could
Speaker 1: actually be a problem. Um. But that that is one
Speaker 1: way of doing it. And then there there are other
Speaker 1: pieces of equipment that can be added to refine the
Speaker 1: capabilities of the signaling equipment. For one thing, there at
Speaker 1: a really you know, nice new modern crossing, you might
Speaker 1: have a lot of solid state electronics and you avoid
Speaker 1: all these these circuit relays and stuff and you just
Speaker 1: you use solid state instead, which it works kind of
Speaker 1: on the same principle, except that there are a lot
Speaker 1: fewer parts. You know, it sends a lot of electronic
Speaker 1: signals directly to the the traffic control system for that
Speaker 1: particular crossing. But but I mean, you know that's it's
Speaker 1: not by any means a universal thing. It's it's all regional.
Speaker 1: And you know, some areas are going to get that
Speaker 1: equipment much faster than others, and some may never get it. Frankly. Yeah, yeah, now, Now,
Speaker 1: Mattiness also said that there are some signals that use
Speaker 1: transceivers built into the boxes that that help identify how
Speaker 1: quickly the train is moving. Um. Basically by measuring the
Speaker 1: voltage um, you know, and judging by the impedance of
Speaker 1: the wheels on the train moving, it can kind of
Speaker 1: tell as the voltage drops how quickly the train is
Speaker 1: going to approach the intersection, and can drop the signals
Speaker 1: at a more appropriate time. UM. But you definitely want
Speaker 1: to make yeah, yeah, English major fair enough. Um. But
Speaker 1: there are also some of the newer intersections also use
Speaker 1: motion detectors, which which can help identify these things. But
Speaker 1: in essence, that's that's what it's doing. It's just basically
Speaker 1: looking for information from the rails themselvesselves in a lot
Speaker 1: of cases. UM. And I think it's it's probably uh
Speaker 1: trickier because in urban environments simply because you have uh,
Speaker 1: you know, more intersections to worry about, and you also
Speaker 1: have more car traffic. And like in the case of
Speaker 1: of the intersection near my house, you've got two roads parallel,
Speaker 1: so you've got two traffic lights to deal with at
Speaker 1: that railroad crossing because the piece of road crosses too
Speaker 1: uh car intersections you know, within my guests probably uh
Speaker 1: hundred feet of one another. So it's a very short
Speaker 1: section of where there are two intersections right on the
Speaker 1: other side of the railroad College avenues that way. So yeah,
Speaker 1: that's uh College Avenue in Decab Avenue. Yeah, yeah, that's
Speaker 1: true that those are from my Atlanta peeps. Yea. So
Speaker 1: it's just one of those situations where you just got
Speaker 1: a lot to be concerned with. And I imagine that
Speaker 1: as time wears on, these uh, these roadways and railways
Speaker 1: will be updated with more solid state technology that will
Speaker 1: give you a better idea of what's going on and when. Um.
Speaker 1: But you know that the the systems that they've had
Speaker 1: have been somewhat uh, somewhat elegant, I think in their design.
Speaker 1: I mean they're just they're simple, and I think sometimes
Speaker 1: that can be for the best. Yeah, uh, keeping keeping
Speaker 1: it simple stupid is always a good uh philosophy to follow.
Speaker 1: And and we should add that the railroad signals. Of
Speaker 1: course we're just talking about the crossing ones. There are
Speaker 1: there are lots more signals that that railroad companies use
Speaker 1: to manage traffic on the rails. And it seems like
Speaker 1: it might you know, for at first blush, you do think, well,
Speaker 1: how how tricky could it be, but then you think,
Speaker 1: wait a minute, this is a dedicated pathway that only
Speaker 1: one vehicle can travel in a direction at in a
Speaker 1: particular area at a time. So it does get really
Speaker 1: complicated when you think, oh, well, how many trains are
Speaker 1: on the system. How many systems are we talking about?
Speaker 1: Because the rules from system to system change a little bit,
Speaker 1: you know, like the rules in the Northeast are slightly
Speaker 1: different than the rules in the southeast. Yeah. Actually, when
Speaker 1: we were starting to talk about what podcasts we wanted
Speaker 1: to record, um, I suggested this to Jonathan, and I said, well,
Speaker 1: let's talk about all the different kinds of signals. And
Speaker 1: then when we got into, uh, the complexities of how
Speaker 1: the systems are triggered for railroad crossings, we realized we
Speaker 1: wouldn't be able to get that in as much detail
Speaker 1: as possible. But if you're interested in knowing more about that,
Speaker 1: please let us know, and you know, maybe we can
Speaker 1: revisit that. But I've always been interested in the switching
Speaker 1: systems and how uh you know they they operate that
Speaker 1: because um, you know, I'm I'm kind of interested in
Speaker 1: trains anyway, but you know, the signals that say, okay,
Speaker 1: wait you can't come this way just yet. And how
Speaker 1: they shunt tracks from one, uh you know, from a
Speaker 1: train from one set of tracts to another set of
Speaker 1: tracks using those electrical systems. So if you if you're
Speaker 1: interested in doing that, please let us know and we'll
Speaker 1: come back to trains in the future. Clearly, Chris needs
Speaker 1: to go see the film Unstoppable. That's the one with
Speaker 1: Denzel Washington and the train. That's the missile, the size
Speaker 1: of the Chrysler building. Stop it, it'll be awesome. Oh
Speaker 1: that's no train, that's a space station. See how many
Speaker 1: random quotes we can throw it? Yeah, I think you
Speaker 1: just mixed up those a little maybe to tad, I'm
Speaker 1: a little loopy today. Al right, guys, well they loopier
Speaker 1: than normal. That wraps up this discussion on text UF. Please,
Speaker 1: if you are interested in giving us topics that sort
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Speaker 1: and Chris and I will talk to you again really soon.
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