# How do US Railroad Crossing Lights and Bells Work?



## Jerry McColgan (Feb 8, 2008)

OK so I am a bit crazy.

I am planning to put a railroad crossing signal pole (full size) complete with flashing lights and bell on my driveway. My thought is to possibly rig it to start flashing the lights when someone drives toward the layout. The bell and lights would have switches so that I could turn them individually on or off according to my plans for the day. One benefit is that the bell could be used to alert me when the UPS or FedEx guys drive up and I do not hear them.

I don't know what power (AC or DC volts and amps) I would need to operate the lights and bell and how to make the lights flash alternately. I would also need to come up with a way for a vehicle to activate the lights and bell and perhaps a remote (wireless) means to turn everything on or off. 

This could also serve as sort of a burglar alarm - how many burglars would hang around after activating a railroad crossing bell and flashing lights?

The trigger for the lights and bell should probably be about 100 feet from the pole and there would need to be some sort of timer or deactivation switch to keep power on and then turn power off after the vehicle has passed. In effect the vehicle would replace a train for activating the signal.

I have no idea how the railroads activate and power their signals but that essentially is what I need to learn.

Thanks,

Jerry

PS for those who may be wondering - my wife wants the signals as much as I do. We are still trying to buy a caboose but our latest offer was turned down so the crossing signal is sort of a consolation prize.


----------



## SlateCreek (Jan 2, 2008)

Jerry, 

You're going to have some difficulty making them work exactly like they did when in service for the railroad. The basics are, the signals usually work on a DC circuit that's backed up by a couple of large batteries in the silver box you see by the side of the track near the crossing. There are three track circuits that make the signals work, and these are "shunted" or closed when the metal wheels of a train allow current to pass from one rail, through the wheels/axle to the other. 

(For the C&S types among us, this explanation is DELIBERATELY simplified!) 

The three track circuits are the "approach" circuits, which extend from where the signal first activates from either direction to the edge of the "island" circuit which covers the actual crossing of the road plus a little on either side. Simply, when a train enters either approach circuit, the signals are activated, and the opposite approach circuit is disabled. When the train enters, and then LEAVES the island circuit, the signals stop. When the train leaves the opposite approach circuit (which is disabled, remember, as we don't want the lights flashing while the train passes through it, after leaving the road) the system resets. If there are signals on the line, or more than one crossing, or switches in either of the circuits, or more than one track, it becomes even more complicated, and remember my explanation here is just the basic approach. If you add gates, there are timers and motor drivers to make them work. That's why that whole case is filled with relays and controllers.... and it's also got to work when the mains power is off. And, as you can see, activating the signals and then stopping and backing out of the circuit, or stopping in the approach circuit on the far side and backing up can have bizarre effects on what the signals do, if this kind of movement is not planned for.... and you can either have signals flashing when a train isn't approaching, or signals that don't come on for an approaching train. Rusty rail, debris, broken bond wires between rails ... all that stuff TOC likes to preach about for track power applies to the 1:1 railroad here, and causes the same kind of frustration. 

More modern signalling involves predictor circuits which monitor how fast a train is approaching and whether it's stopped, and modifies the "lead time" of the signals accordingly, so that if the train stops before reaching the crossing, the lights stop, and if a train enters a circuit timed ro a 70 mph train going 10 mph, the signals will wait until he's closer to the crossing so that the lead time is the same 27 seconds (well, that's the minimum, anyway) regardless of speed. 

But, the bottom line is, prototypical, you'd need to shunt a track circuit, and your UPS fellow isn't going to do that. For your yard system, what you probably need is a timer, a 24 volt relay, and a "wig wag" flasher capable of handling 24 volts. Using the kind of trigger a gas station bell uses (you know, the hose with the pressure switch...) the trigger would activate the timer, which would turn on the 24 volt relay, sending power to the bell and the wig wag flasher.... operating both for 30 seconds or whatever time made sense to you, and then stopping. It'd activate again as he left the driveway, but that might not be a bad thing. You could power the whole affair with a couple of car batteries and if you wanted to be really slick, you could use a charger and solar panel to keep the whole thing charged and ready. 

Matthew (OV)


----------



## Semper Vaporo (Jan 2, 2008)

Mine has 12-V incandescent automotive bulbs. I run them from a Radio Shack 12-V power supply with a "cigarette lighter" socket on it that is designed to allow a car type device to run off of 120VAC; like to test a car radio in the house on a work bench.

For remote control I have used two different methods, but neither are like you are wanting. I put an Edison base (a light bulb base with a plug outlet instead of a light on the other end) into my garage door opener light socket, and then plug the power supply into it. When the garage door is activated the opener "lamp" circuit turns on and that then powers the flasher circuit until the garage door opener lamp circuit times out. 

The other remote method I have used is a Sears 120V Remote Lamp controller. It is a small receiver and relay in a box with a plug and socket and a small handheld/pocket transmitter that toggles the relay in the receiver. I have the neighborhood kids convinced the grade crossing lights are voice activated and it only works with my voice. I have the control in my pocket and click it while saying "Lights On" or "Lights Off". The kids stand out there all day trying to mimic my voice to get the lights to work. (I allow it sometimes by clicking the button at random times!)


If you don't have a RR Flasher module to operate the lamps you can use a car Turn Signal Flasher and a 12V SPDT Relay (Automotive Horn relay)... but the circuit is a bit strange.

Automotive Turn Signal Flashers are strange beasts. They contain a heater that heats up when current flows and when it is hot enough it "shorts out" the heater. Usually two bulbs (in parallel on the car, front and rear turnsignal lamps) are in series with the flasher. The two bulbs draw enough current to heat up the heater, but with the heater in the circuit there is not enough current flow the cause the bulbs to light up. When the heater is hot enough to trigger the short, then enough current flows to light the bulbs. The heater then cools enough to open the short and the bulbs go out and the heater gets hot again to the point where it shorts itself out again. If you look really closely at your cars turn signals you may notice that the bulb glows really dim and then gets bright and goes back to dim... that dim part of the cycle is when the heater is heating up and the bright time is when the heater is shorted out and cooling off.

In my circuit the relay is a Single Pole Double Throw (SPDT) and was supposed to switch between the lamps. When the turn signal flasher toggled that would toggle the relay and the relay in turn would select one lamp when de-energized and the other lamp when energized. That was my initial idea anyway! 

BUT! The relay does not draw enough current to let the flasher heater get hot. So, I had to wire one lamp in parallel with the relay and that one lamp and the relay do draw enough current. You could use a SPST relay if it is a Normally Closed (NC) relay so that when the flasher energizes the relay it turns OFF the lamp is is controlling, but that type of relay is rare and a SPDT is readily available, you just don't use the Normally Open (NO) contacts.

Now to complicate matters! I just built a miniature set of Grade Crossing Lights... set to demo them at the next CVGRS meeting TOMORROW (Sunday)! So your question was quite timely!

I used LED type replacement trailer lamps for this model. The LED lamps do not draw enough current to activate a cheap Automotive Turn Signal Flasher! I had to use a 50-Watt 5-Ohm resistor in parallel with the relay to draw enough current to get the thing to work. Unfortunately, this resistor gets REALLY HOT! (think how hot a 50-Watt light bulb gets!)

I am trying to find a different automotive flasher device that will work on lower current. I also am trying to find what kind of flasher is used on some cars that have front and side lamps that flash alternately... that would eliminate the need for the relay! I know I have seen cars that do this, but I don't know what make/model/year to tell the AutoZone clerk so he can sell me one! I have seen three different vehicles in the last week that had the front and side bulbs flashing alternately, one was a pickup truck and one was a small compact car, neither did I see long enough to get a make/model ID (I was going the other way in traffic and I don't recognize cars all that well... I was lucky to be able to say one was a "truck" and one was a "car"!). The 3rd vehicle I was able to at least identify as a Jeep Cherokee, but I have no idea the year.

If anyone knows what Make, Model and Year car has the alternately flashing turn signals, please post it here and I will attempt to see if the device will work with LED type lamps. THANKS if you can!

So far my "Prototype" miniature grade crossing flasher lights have cost me about $150 to $200, but I think I can get that down to less than $100 once I decide on what are the best sources of the parts are. The most expensive parts have been the electrical box to hold that HOT resistor and the PVC conduit elbows and such used for the pole and cross arm to hold the lights. The rest is pretty cheap... including the relay, flasher and lamps. I am sure better and cheaper parts are obtainable.

I will post a YouTube video "soon" of what I have.


----------



## SlateCreek (Jan 2, 2008)

The problem with using a 537 relay (the turn signal flasher) is that you get an uneven flash pattern ..... FLAAAAASH ... flash... FLAAAAASH....flash .... if you're only flashing one light, it's OK, but quickly you'll see one stays on a lot longer than the other. (in a car, where one is your flasher, and the other is the light on the dash, nobody cares.) 

You can use a police "Wig Wag" flasher, solid state, even rate... but it's generally WAY too fast (3 per second, often!) for what you want. Better to build one, or use something else with an even, slow flash rate. Commercially, there's options like this: http://www.trafficlights.com/b2ad.htm but that's just a quick google... there may be better ones out there. 

Matthew (OV)


----------



## Semper Vaporo (Jan 2, 2008)

Both of my crossing lights (the real one and the miniature one) flash at a fairly nice uniform alternation rate... maybe I have been lucky getting the loads balanced for the particular flashers I have used. (I did burn out one flasher on the 1:1 real set one time and bought a physically larger replacement... not that they means it is a better one or will last longer).

I just took more video of both of them and will attempt to get something on YouTube by this evening.


----------



## Semper Vaporo (Jan 2, 2008)

Well, ya cain't say I din't warn ya'! (Well, I guess you could say anything ya wants, but ya'd be wrong!)


----------



## Jerry McColgan (Feb 8, 2008)

I appreciate the responses. They help a lot.

The light bulbs are marked 10V/25W and it seems that the system operates at 12 volts DC. 

From the link it seems that the Model D2 12VDC Adjustable Alternating Flasher may be what I need. 

http://www.trafficlights.com/d2ad.htm

The D2 is marked 50 watt maximum and two 10 volt 25 watt lights at 12-14 volts would probably exceed the 50 Watt maximum. I will probably send them an email to check on it.

Although it is not marked the bell probably works on 12VDC as well.

That would leave a triggering and delay mechanism to be worked out.

Perhaps a nearby 12 volt marine battery with a trickle charger would work for a power supply and an outdoor motion detector light (with a built in delay) could be used to power a 120VAC relay instead of a light.

I have a pole with a circuit breaker panel that is not far from where I am thinking about putting the signal pole in so that would be a ready source for 120VAC and pole mounted switches could be used to turn the light and bell circuits on or off.

Everything is more expensive than I anticipated ($60 just for a 13' tall 4" wide steel pole) but once it is in there will be little expense of running it.

I have about decided that the only really safe mounting will be to bury 3 feet of the pole in the ground (in concrete). Everything is far heavier than I had expected and I'm afraid it would take quite a large concrete base to support a surface mount of the pole.

That will only allow 7 feet from the ground to the lights (9 feet seems to be about standard from my checking some working signals). I don't know if it would be worth it to weld an extra few feet to the pole or not.

The project is proceeding well but every step seems to result in more questions.

I am a little uncomfortable connecting a 12 volt battery that may put out 14 volts when fully charged to light bulbs marked 10 volts and to an unmarked bell.

Jerry


----------



## SlateCreek (Jan 2, 2008)

Jerry, 

Wouldn't worry about the extra couple volts. The current draw should pull it down anyway... but it's just a light bulb. Most automotive 12 volt bulbs are being fed 13.something by the alternator anyway. You could always use automotive bulbs instead.

Does your sign have four bulbs or two? If it's only two, remember you're only turning on one at a time..... 

Matthew (OV) 

Oh, and semper... nice idea.. Do not STEP on tracks!


----------



## Jerry McColgan (Feb 8, 2008)

Posted By SlateCreek on 11/09/2008 2:05 PM
Jerry, 

Wouldn't worry about the extra couple volts. The current draw should pull it down anyway... but it's just a light bulb. Most automotive 12 volt bulbs are being fed 13.something by the alternator anyway. You could always use automotive bulbs instead.

Does your sign have four bulbs or two? If it's only two, remember you're only turning on one at a time..... 

Matthew (OV) 

Oh, and semper... nice idea.. Do not STEP on tracks!



Hi Matthew,

Good point. There are only two lamps and only one would be illuminated at a time.

I too LOVE the "Do not step on tracks sign" - how would someone like me get one? 

Since my outdoor switches are now LGB Nickel Plated and thus virtually irreplaceable I need a sign like that. Someone saying "Sorry" after their child may have destroyed one of those switches would not help much.

Thanks,

Jerry


----------



## Semper Vaporo (Jan 2, 2008)

The cross-bucks are 2-inch self adhesive vinyl letters stuck on white styrene poster board (1/4" thick styrene sheet with paper on both sides) and sprayed with a rattle can clear coat.

I made the black signs using the Windows PAINT. It didn't make the letters as large as I wanted so I used the stretch function to increase the size to what I wanted. Unfortunately, that function then left the edges of the letters a bit jagged, so I smoothed the letters manually with the pencil tool. Then I decided I wanted white letters on black so I did a flood fill of the background with red, then filled each letter with white, then refilled the background with black... (would of been a bit less tedious if I had thought ahead and set the foreground and background color before I entered the text!). I then printed the black signs on my laser printer, cut them out and used a spray adhesive to glue the paper to some black styrene poster board. Then I sprayed the whole sign with the same rattle can clear coat. I bought some 6-mm jewels at Michaels and a couple of boxes of "glue dots" (a long strip roll of wax paper with 5-mm glue spots every inch) and spent one evening picking up one jewel and sticking it to one glue dot, after making a dozen or so of these I then picked the glue dot/jewel off the wax paper strip and stuck it on the letters.

I have not yet assembled a parts list (I bought way too many parts that didn't work and I have not pared the list down to just the ones I did use). Most parts I got at the hardware store. I only had to fabricate a couple of parts from scratch and drill a few holes in some of the hardware store parts, but even the ones I fabricated could be something again from the hardware store. Many substitutions could be made in the hardware. 

The lights are replacement "Trailer Lights" from Harbor Freight. The pole and fittings are gray PVC electrical conduit (which might be a bad choice since I am detecting some leaning/drooping of the pole). The cross arm is attached using two "T" fittings, but I am sure a "+" fitting is available "somewhere", but not at MY local hardware store. A lot of the fittings were very expensive (the 4X4 electrical box was $19.95!) and some substitutions might be cheaper. I happened to have the 3/4" thick aluminium plate on hand... other things could be used... I even considered just putting a pipe out the bottom to stick in the ground instead of the plate I used (might be cheaper too, the flange on the bottom was $9.50.

The 5-Ohm 50-Watt resistor I got from Iowa Radio (a local electronics shop), I don't know if Radio Shack has anything like that in stock, but I assume it is available via the Internet "someplace". If you use incandescent lights you don't need the resistor, but since the incandescents get hot, you may need to use metal for the black targets around the lights (I used plastic paint can lids). The "visor" over the lights are cut up AquaFina (tm) water bottles, but the most recent pack I got has ribbed sides and would be unsuitable... there are other brands of pop and water bottles that have smooth sides... a metal visor could be cut from a pop/soda can. All were painted black with a rattle can of bar-B-que paint (I happen to have on hand) and it seems to have stuck to the plastic quite well.

It all runs off of a 12V battery pack that has a built-in air pump for inflating automobile tires (slowly!) and has a automotive type 12-V power socket in it. I mounted an On/Off switch in the 4x4 electrical box, but it is not really necessary... at the time I wasn't sure exactly where I was going to obtain the power and wanted to be sure I had a local power switch. I did not fuse it, but probably should have. It draws about 3 Amps when running (the LEDs don't draw much current but the flasher needs to draw that much to work. (If I can find a different flasher that current could be reduced considerably. The 5-Ohm 50-Watt resistor get HOT... a bit too hot. I mounted it in the metal electrical box by drilling and tapping a hole on opposite side about the center of the box. I put a machine screw in each hole to hold the resistor up and away from everything else. The resistor is a hollow ceramic tube so the screws just go into the ends, not that that do anything other than capture the resistor in the middle of the box.


----------



## Jerry McColgan (Feb 8, 2008)

The project is moving along. The pole, lights and bell are now up and I tried the bell with a 12 volt automobile battery and it works. 

Since the bell is working on 12 volts I've decided to continue and power the lights also with the 12 volt battery.

Rather than pay for a meter just to power the railroad crossing I may just put a car battery nearby and use it to power the signals - perhaps with a solar cell recharger.

That still leaves me with finding a way to trigger the lights and a timer to keep them going for 15 - 30 seconds. If I can do that with a 12 volt dc circuit as well it would be great.

I ran across a great article "Crossbucks, flashers and gates" in the July 1996 Trains Magazine (page 74) that explains how the system works. Finding the article was a lucky coincidence for me.

Jerry


----------



## Jerry McColgan (Feb 8, 2008)

Posted By SlateCreek on 11/08/2008 1:30 PM
The problem with using a 537 relay (the turn signal flasher) is that you get an uneven flash pattern ..... FLAAAAASH ... flash... FLAAAAASH....flash .... if you're only flashing one light, it's OK, but quickly you'll see one stays on a lot longer than the other. (in a car, where one is your flasher, and the other is the light on the dash, nobody cares.) 

You can use a police "Wig Wag" flasher, solid state, even rate... but it's generally WAY too fast (3 per second, often!) for what you want. Better to build one, or use something else with an even, slow flash rate. Commercially, there's options like this: http://www.trafficlights.com/b2ad.htm but that's just a quick google... there may be better ones out there. 

Matthew (OV)


Hi Matthew,

I appreciate the link to trafficlights.com. I ordered their D2 12 V Wigwag Light Flasher. At $35 plus $7 shipping there may be better or cheaper choices but by the time I drove around looking at alternatives I would probably have spent more on gas and not ended up with anything as good or better. At least they are a company that makes a flasher specifically for railroad crossings. Additionally, at only 2 by 2 1/2 inches I should not have a problem fitting it into the pole.

This should get the pole totally functional. That will leave the triggering mechanism to work out but all I will now need will be a SPST contact to energize the signals and I may elect for multiple options including remote radio control.

Thanks,

Jerry


----------



## jamarti (Jan 2, 2008)

Not sure if this would work or is the same as a "wig wag" flasher mentioned earlier, but I see alternating flashing lights every day, on a school bus. Try the local school bus garage. The mechanic there might have a clue. 

When on the fire department our rescue/equipment van had alternating lights. When the flasher went out, we tried like heck to find a replacement at the local auto parts store. Nada....till someone mentioned the school bus flasher.


----------



## Guest (Nov 19, 2008)

One thing you don't want to do is get jumper cables and use them on the tracks. I had over several years in the Police Dept calls for such and only caught 1 group because they was to drunk.
Toad


----------



## Jerry McColgan (Feb 8, 2008)

A small package arrived yesterday. It was the D2 12 V Wigwag Light Flasher from trafficlights.com.

It took me quite awhile to get all the wires sorted out and then cut to fit etc. but I am happy to report that the RR Crossing is now 100% operational aside from having a means of remote activation set up. The timing is perfect as my wife has been out of town working all week and she has been looking forward to seeing it. When she left town all that was up was the pole.

I think I figured out why the RR got rid of it. The wiring was screwed up and I spent half the morning working out the problems.

Jerry


----------



## Semper Vaporo (Jan 2, 2008)

HOW can they screwup 3 wires? One to each light and one return from both.


----------



## Jerry McColgan (Feb 8, 2008)

I have not sorted out the reason why (because I would have to remove the terminal block and that would mean disconnecting all wires.

Actually the signals have a lot of connections.

2 to the bell and at least 6 in the bell (8)

2 to each light and 6 inside each light (16)

4 to the flasher relay and then back to the terminal blocks (8)

2 for the power input and then to the power source (4)

That allows 36 opportunities for something to be connected wrong.

Most all of the wires had been cut.

The main problem was with the terminal block. There had been two and if I had used the other everything would have worked.

The terminal block I used was wired for 3 pairs of screws. The outside two pairs were properly connected to each other with a metal strip. The inner pair (for reasons I don't know because I left it alone) had a conductive metal strip between them but oddly were NOT connected electrically.

I checked 3 other identical terminal strips and all of them were connected electrically in pairs.

The problem slipped in when I realized the flasher relay would fit better on the left. I had removed the right terminal block but not tested the left terminal block. I moved the left terminal block to the right without checking it for continuity (heck it was pretty basic - 3 pairs of screws with visible metal strips between the pairs). 

The result was that the bell and one light worked but the other did not yet it showed continuity. Apparently there was enough continuity to show a connection but not enough to make the light work even though the connections were screwed down tight.

The light is old and the connections held with rust and corrosion so everything took more effort than expected but it is done now and works nice.

A nice surprise was that one red lens is glass and the other is plastic. The plastic one looked like it would not pass light well but after I cleaned everything it did not look better but when the lights flash there is no apparent difference.

Jerry


----------



## Jerry McColgan (Feb 8, 2008)

I thought I was about done with this project. The signals are up and working and I finally decided on a means to activate them with The Reporter motion detector:

http://www.radioshack.com/product/index.jsp?productId=2104409&tab=features

It has a 10 amp switch and I would have sworn that I read that it had 15 - 30 second delay but I was wrong (and I cannot find any driveway vehicle detector that does have a delay - to keep the lights and bell working until the signals are passed).

If I keep the Reporter I need to find a way to now add a 15 - 30 second timer to the circuit.

The Reporter will close the circuit connecting a 12 volt battery to the lights and bell. It seems that I now need a 12 volt relay to keep the circuit closed.

Any suggestions or recommendations?

Thanks,

Jerry


----------



## SteveC (Jan 2, 2008)

Jerry

Maybe this may be of help.

[url]http://www.aaroncake.net/circuits/relaytim.asp[/b][/url]


----------



## Jerry McColgan (Feb 8, 2008)

Posted By SteveC on 11/23/2008 3:59 PM
Jerry

Maybe this may be of help.

[url]http://www.aaroncake.net/circuits/relaytim.asp[/b][/url]



Hi Steve,

I appreciate the link. I may use it but I am hoping to find a ready built circuit if possible.

I may try just using a motion detecting outdoor light instead of the Reporter detector since a light has a built in timer.

Thanks,

Jerry


----------



## SlateCreek (Jan 2, 2008)

http://www.dallee.com/Timers.html


----------



## Jerry McColgan (Feb 8, 2008)

Posted By SlateCreek on 11/25/2008 6:36 AM
http://www.dallee.com/Timers.html


That sounded good until I saw "Seperate power of 14-18 volts is required" 
I was/am hoping to end up with a complete system running from a 12 volt marine battery.

I'm going to check with some of my old electrical distributors as there is a good chance they will have a 12 volt relay with a timer and would probably give me wholesale prices on it if they do.

Thanks,

Jerry


----------

