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RRPhotoguy

@172.56.27.x

How do railroad gates work?

Anyone have an idea how they work


alphapointe
Don't Touch Me
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join:2002-02-10
Columbia, MO
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1 recommendation

»en.wikipedia.org/wiki/Railroad_c···_devices
--
"When the hammer drops, the bullshit stops"


RRPhotoguy

@172.56.27.x
Its interesting but doesn't say much about how they work. there has to some kind of system which causes them to operate.


SparkChaser
Premium
join:2000-06-06
Downingtown, PA
kudos:4

1 recommendation



54067323

join:2012-09-25
Tuscaloosa, AL
reply to RRPhotoguy
said by RRPhotoguy :

Anyone have an idea how they work

Internally they are nothing than a 12 volt gearmotor operating a counterbalanced gate.

lutful
... of ideas
Premium
join:2005-06-16
Ottawa, ON
kudos:1
reply to RRPhotoguy
Click for full size
said by RRPhotoguy :

Its interesting but doesn't say much about how they work. there has to some kind of system which causes them to operate.

It is not clear what you mean by "work" or "operate" ... the electro-mechanical movement which lowers/raises the gate or the electronic control behind it?

All modern railways operate signalling networks to detect the presence and speed of trains along their tracks. Above diagram says "many metal cables" ... but most of them have been converted to optical fiber.

Positive Train Control (PTC) system being implemented in US:
»www.fra.dot.gov/Page/P0152


54067323

join:2012-09-25
Tuscaloosa, AL

1 edit
said by lutful:

All modern railways operate signalling networks to detect the presence and speed of trains along their tracks.

That’s incorrect, there are thousands of miles of dark track operated under train orders in North America and un-like in your diagram Highway Grade Crossing signals are not operated by the network they are operated by track circuits.


RRPhotoguy

@172.56.27.x
reply to SparkChaser
Thanks that's it didn't know what that was called


jrs8084
Premium
join:2002-03-02
Statesville, NC
kudos:1
Reviews:
·AT&T U-Verse
A bit OT, but there is a small line RR (20 miles) that delivers to local businesses. I have to cross their tracks on my way to work. About 2010, they were having equipment failure and the gates were staying down when it was obvious no train was around. (And the RR doesn't operate early in the morning.) A lot of us ended up being late several times because we had to turn around and take an alternate route.

I called the office, and politely explained of the fault, questioning if they new this was happening. They told me "yeah, we don't know what is wrong-we keep trying things. Drive around the gates"

I was a bit dumfounded they would suggest that. But, the problem never occurred afterwards.


54067323

join:2012-09-25
Tuscaloosa, AL
said by jrs8084:

I called the office, and politely explained of the fault, questioning if they new this was happening. They told me "yeah, we don't know what is wrong-we keep trying things. Drive around the gates"

I was a bit dumfounded they would suggest that. But, the problem never occurred afterwards.

Being a short line, I am guessing they where still using DC based track circuits and those types of circuits are prone to dropping the track circuits vital relay due to conduction between the rails, this "short" between the rails causes the vital relay to go from picked to dropped, activating the crossing signal.

lutful
... of ideas
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join:2005-06-16
Ottawa, ON
kudos:1

1 edit
reply to RRPhotoguy
Click for full size
said by RRPhotoguy :

Thanks that's it didn't know what that was called

Since your thread title will show up during Google search, let me provide information on "more modern" railway crossings some of them will encounter in their neighbourhoods.

»www.moxa.com/newsletter/connecti···t_02.htm

Exposed to the elements, the clearance zone of a level crossing is shared by trains, vehicles, pedestrians, and even wildlife and wind-blown debris. Although we always want to avoid collisions between a train and a stranded vehicle or pedestrian, it may not be necessary to stop a speeding locomotive each time an agile deer leaps across the tracks.

... smart level crossing systems are now adopting the latest in CCTV surveillance and image processing technology to visually inspect boom gate conditions, identify trapped objects, and monitor the movements of the object in real time.

... Tucked inside a space-saving wayside cabinet, compact RTU controllers can connect all the myriad I/O, Ethernet, and serial interface sensors at a level crossing to an integrated wayside monitoring system.

More specifically, by sending error messages about potentially malfunctioning barriers, motors, lights, and alarms from a far-flung railroad crossing to the OCC, advanced RTU controllers enable railway operators to instruct a speeding train to slow down or stop well before it reaches an intersection.


54067323

join:2012-09-25
Tuscaloosa, AL

2 edits
said by lutful:

Since your thread title will show up during Google search, let me provide information on "more modern" railway crossings some of them will encounter in their neighbourhoods.

Incorrect, in America track circuits are required to be the controller of Highway Grade Crossings, that is an FRA regulation based on well known AAR designs...

This is an example of just one of many devices designed for such a purpose versus what is depected your model railroad diagram.

»getransportation.com/rail/rail-p···p-3.html


54067323

join:2012-09-25
Tuscaloosa, AL
reply to lutful
said by lutful:

[ it may not be necessary to stop a speeding locomotive each time an agile deer leaps across the tracks.

Screw the deer, they get just hit and killed with no damage to the locomotive, heck even cars are no match for a locomotoive running at track speed.

This car was nailed at 45 mph and was sent a good 700 feet down the ROW, the train itself continued on down the track for another half mile before finally stopping. Lucklly the driver had enough common sense to abandon the car after realizing he was boxed in on the track and had no where to go.






Thane_Bitter
Inquire within
Premium
join:2005-01-20
Given the colour and gas mileage of that boat I can't help but wonder if the breakdown was a tad too convenient to occur on the tracks.


54067323

join:2012-09-25
Tuscaloosa, AL

1 recommendation

A little Bondo and she will be as good as new.


54067323

join:2012-09-25
Tuscaloosa, AL

3 recommendations

reply to RRPhotoguy
said by RRPhotoguy :

Anyone have an idea how they work

Yes and since this thread got a little (pardon the pun) sidetracked with semi incorrect attempts to explain ATC/PTC which are acronyms for Automatic Train Control and Positive Train Control, and having a little spare time I would like to clear up a number of misconceptions about those systems in the U.S.

Originally the first attempts to electrify railroad signaling involved DC based systems, a section of track would be insulated and at a distant location a battery with a series resistor would be connected to the rails, with one side positive and the other negative, at the signal a vital relay would be connected to the rails and the battery present would “pick” the relay up, indicating a “clear” block, as a train entered that block the wheels would short out the battery causing the vital relay to “drop” activating a signal or crossing gate.

The system worked well and is still in use in many parts of the U.S., its disadvantages where rusty rails might prevent a good short and fail to drop the vital relay and more commonly conduction between the tracks via the ties caused false signaling.

Another problem with DC signaling was it didn’t take into account variations in train speed and didn’t play well with electrified rail systems.

The solution was an AC signaling overlay, AC allowed for a measurement of variable loss of signal versus the zero / one nature of DC signaling, this allowed for speed detection, preventing a premature lowering of a crossing signal by a slow train, which commonly resulted in drivers going around the gates and sometimes getting killed in the process and more importantly for the railroad a delayed lowering of the gates for a fast train, allowing it to enter the island before the gates where lowered, creating a liability for the railroad.

AC signaling also allowed for ATC, which while simple is not deployed by “all major railroads” in the U.S., one only needs to look toward the New York derailment to understand that fact had ATC been in place (and working) that derailment and the subsequent deaths and injuries would not have happened.

How does ATC work, well it like many things rail related is to say simple and robust, the signaling consists of multiple devices transmitting into the rails, tones if you will, on the locomotive induction pickups mounted where they are just above the rails receive the tone(s) and send then to a processor.


ATC Locomotive Induction Pickup


In the locomotive the processor decodes the tones and activates in cab displays and if those displays are not acted upon, can blow the brake line and put the train into emergency braking.

In the cab a heads up display will indicate approaching signals.


Heads Up Cab Display


On the engineers side it provides setup controls and ATC indications.


Engineers Display


And on the conductors side another display is placed.


Conductors Display


Trackside components that link into ATC are but not limited to;

Dragging load detectors, internally they contain a basically dynamic microphone mounted to a robust metal housing.


Dragging Load Detector



Dragging Load Detector Detail


Hotbox (overheated axle bearing) detectors, note the dragging load shields for the IR camera.


Hotbox IR Camera



Hotbox IR Camera


And many more.

The second system out there is PTC which takes ATC and adds GPS, on-board diagnostics and interactive displays, in the U.S. these systems will gradually move away from AC signaling and go to RF on 220MHz, which has been accepted to by both the FRA, FCC and the AAR.

None the less regardless of signaling methods, there is something about guys and rails.

My son years ago sitting in the cab of a CSX locomotive waiting for a clear signal for us to continue heading south.


Ready To Roll

JoelC707
Premium
join:2002-07-09
Lanett, AL
kudos:5
said by 54067323:

as a train entered that block the wheels would short out the battery causing the vital relay to "drop" activating a signal or crossing gate.

I remember my dad telling me years ago that you could take a long enough metal bar and lay across the rails and it would trigger the crossing signal. Never tried it but I thought it was pretty cool.

said by 54067323:

In the locomotive the processor decodes the tones and activates in cab displays and if those displays are not acted upon, can blow the brake line and put the train into emergency braking.

OK, I know the whole "it's just a movie" thing applies but did you watch the movie Unstoppable? I've wondered if something like that were actually possible to happen and from the looks of this, I'd say no. Of course as you said, not every area has adopted ATC/PTC so maybe it's possible in the "legacy" areas?


leibold
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Sunnyvale, CA
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Reviews:
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The signal system on the railway between San Francisco and San Jose was completely replaced less then 10 years ago to enable trains passing each other on the opposite track (something that greatly improved commuter train performance). Despite that significant modernization no positive track control was installed at that time. While I don't know how representative this is for the rest of the US, my guess is that PTC is still the exception and not the rule.
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54067323

join:2012-09-25
Tuscaloosa, AL
reply to JoelC707
said by JoelC707:

I remember my dad telling me years ago that you could take a long enough metal bar and lay across the rails and it would trigger the crossing signal. Never tried it but I thought it was pretty cool.

That will work and in fact there have been incidents where hoodlums have laid pipes and other conductive objects across the rails to change a track signal to red, causing an approaching train to stop and contact the dispatcher for orders as what to do next, as the train is stopped they break into the freight cars and loot them.

OK, I know the whole "it's just a movie" thing applies but did you watch the movie Unstoppable?

While I have made a few train related videos I don’t watch train movies as I have a tendency to bitch too much about the use of dramatics over facts.

I've wondered if something like that were actually possible to happen and from the looks of this, I'd say no.

Based on what I have read of the plot it actually happened, do a search on the CSX train 8888 incident in which a runaway ghost train was stopped by coupling a locomotive to the rear and pulling it to a stop and recently up in Canada a not properly tied down CN consist became a ghost train which later derailed and ripped a small town a new one.

Of course as you said, not every area has adopted ATC/PTC so maybe it's possible in the "legacy" areas?

Actually very few areas in the U.S. outside of the NE corridor utilize ATC.


54067323

join:2012-09-25
Tuscaloosa, AL

2 recommendations

reply to leibold
said by leibold:

While I don't know how representative this is for the rest of the US, my guess is that PTC is still the exception and not the rule.

ATC and PTC are most certainly the exception versus the norm.

As I stated in a reply earlier to a poster falsely claiming that all "modern U.S. railroads utilize signaling,” the fact is there are thousands of miles of un-signaled “dark” track in the U.S., these rails are operated under train orders and do so without incident, train orders are really nothing more than a dispatcher, by radio, telling a conductor you may operate your train between these two mileposts, in a certain direction, at a certain speed and then as the train approaches the last milepost and well within stopping distance of it, the conductor will contact the dispatcher and request another train order allowing the train to proceed into the next block and continue on it’s way.

These rails have no trackside signals and most of the time highway railgrade crossings are marked only with a couple of cross-bucks and a sign with stern warning for drivers to stop, look and listen before crossing the rails. Most drivers do, but some die when they do not.

The train has the right of way and the mass to enforce that rule...

lutful
... of ideas
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join:2005-06-16
Ottawa, ON
kudos:1
reply to RRPhotoguy
I linked to a URL earlier from MOXA, who makes controllers for modern level crossings.

They have a detailed whitepaper for download after registrartion:
»www.moxa.com/support/request_cat···?id=1359

"How to Make Railroad Level Crossings Safer and Smarter"

High-traffic railroad level crossings remain a global safety concern despite the widespread use of active warning systems to clear the tracks for oncoming trains.
...
Consequently, transportation and safety professionals are increasingly deploying advanced data acquisition and IP video surveillance technologies to provide more complete and accurate information to make existing level crossings smarter and safer.


54067323

join:2012-09-25
Tuscaloosa, AL
said by lutful:

"How to Make Railroad Level Crossings Safer and Smarter"

Education is the only real solution to that problem, too many people fail to understand trains do not stop quickly, it can take a freight train well over a mile to stop after a brake application and by then the train is usually well beyond the reason for stopping and the damage is complete.

Now in the U.S. some railroads have installed CCTV cameras at high profile Highway Rail Grade crossings, high profile meaning there is a history of a higher than normal number of train versus vehicle collisions at that crossing and while these cameras are monitored at a central location, a vehicle sitting on the tracks is not just cause to stop an approaching train, as the chances are good the car will be off the tracks long before the train gets to the crossing and stopping a train, especially by blowing the brake line and putting it into emergency is actually dangerous.

As such the cameras have one real purpose and that is to provide video evidence that the railroads crossing signals did operate properly and the driver of the vehicle did not, reducing the railroads liability when the heirs of the vehicles occupants sue the railroad.

As for education, in the U.S. there is Operation Lifesaver which is a non-profit organization dedicated to rail safety education which has programs ranging from grade school to adult driver safety courses.

Still as OL points out, about every three hours a person or vehicle is hit by a train.

»oli.org/

And even with all the education efforts people still do deadly things with trains that no level of technology can prevent.

This is the largest piece of a bicycle I could find, which had been ridden by a 15 year old boy who played chicken with a locomotive and lost at the game, needless to say he never made it to his 16 birthday. FWIW this wheel was on the ground about 200 feet from the point of impact, the boys body was hurled about another 75 feet further down the track.

Try to imagine the G forces at play when accelerating from 0 to say 50 MPH in a millisecond or two. It is horrific...




And yet with all the education out there still too many people fail to understand the physics of being hit by a train, one of the best descriptions of a train versus car collision I ever heard was uttered by A&E’s Bill Kurtis, and I am paraphrasing “a train hitting a car is the equivalent of a car running over a soda can.”

It’s all about mass, times velocity squared.



pike
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join:2001-02-01
Washington, DC
kudos:3

1 recommendation

reply to RRPhotoguy
54067323 See Profile did a pretty nice job explaining track circuits and cab signaling. There's a few things I'd like to add. A third type of track circuit typically not found on freight/commuter systems but rather subway railroads is the audio frequency style. Rather than using voltage to operate the track occupancy relay an audio frequency at a specified code rate is induced to the rails which is decoded at the other end of the block. AF systems have a major advantage in that they obviate the need for insulated joints between blocks which allows for continuously welded rail. CWR makes for a smoother ride for passengers and less wear on both the rail and the wheels/trucks.




An impedance bond, or more commonly called a Wee-Z bond (trademark of GRS) is the device that couples the AF or voltage to the rails and acts as a transceiver.

Another interesting wayside device is a microphone that is tuned to listen for the distinctive thuds of a flat spot on a rolling rail car wheel. The offending car can be removed from service at the next opportunity to have the wheels turned in an underfloor lathe.

The runaway oil train that leveled Lac Magentic in Canada was not CN's. The ROW, locomotives, and engineer were that of the Montreal, Maine, and Atlantic Railway.


54067323

join:2012-09-25
Tuscaloosa, AL

1 edit

1 recommendation

said by pike:

Rather than using voltage to operate the track occupancy relay an audio frequency at a specified code rate is induced to the rails which is decoded at the other end of the block. AF systems have a major advantage in that they obviate the need for insulated joints between blocks which allows for continuously welded rail. CWR makes for a smoother ride for passengers and less wear on both the rail and the wheels/trucks.

The photo of the ATC locomotive pickup that I posted is part of the Harmon system which does utilize audio signalling, the only difference I can tell is the cabling for that system is just welded to the CWR versus using a coupling coil and I beleive the only reason a coupling coil was used in the photo you posted is that is an electrified railway.

Another interesting wayside device is a microphone that is tuned to listen for the distinctive thuds of a flat spot on a rolling rail car wheel. The offending car can be removed from service at the next opportunity to have the wheels turned in an underfloor lathe.

Yup a flatspot detector and you are quite correct, internally it is nothing more than a dynamic microphone on steriods.


Flatspot Detector


These and the other devices are commonly located with a Defect Detector which gathers the inputs from the trackside devices and the broadcasts the results on the "road" channel.

If all is well the broadcast will go something like this "defect detector milepost 3-3-0 no defects remember safety first."

Now if it's pouring down rain or the middle of a blizzard, inevitably the detector will kick out something like, "defect detector milepost 3-3-0 hotbox detected axle 4-1-5 end of transmission."


Defect Detector Cabinet



Defect Detector Cabinet


The runaway oil train that leveled Lac Magentic in Canada was not CN's. The ROW, locomotives, and engineer were that of the Montreal, Maine, and Atlantic Railway.

Ah good info, I am not at all up to speed on Canadian rail, but when I attended EMD's 75 annversery I did see a lot of CN rolling around IL and when I think canadian rail I think CN.


EMD


BTW a bit off topic but have you ever seen a locomotive on a flat bed trailer?


Locomotive Shell


lutful
... of ideas
Premium
join:2005-06-16
Ottawa, ON
kudos:1
reply to pike
Click for full size
said by pike:

The runaway oil train that leveled Lac Magentic in Canada was not CN's. The ROW, locomotives, and engineer were that of the Montreal, Maine, and Atlantic Railway.

Serious mistakes were made by the driver and firefighters to cause that tragic accident. No design of the level crossing would have stopped that runaway train.

My personal interest in "smart" level crossings come from this crash which killed 6 and injured dozens and would have killed both me and my wife on September 18, 2013 under slightly different circumstances.

More on that crash including my theories here: »Via Train vs. OC Trampo bus


54067323

join:2012-09-25
Tuscaloosa, AL
said by lutful:

No design of the level crossing would have stopped that runaway train.

No, but a very simple and inexpensive ($1148.00) device could have prevented it from ever happening.

»www.aldoninfo.com/buyportablederails.html

Anytime a train is to be tied down on a grade it is prudent to place a derailer on the rail(s) a few feet downhill from it.

Then should something go wrong, at the worst there will be a truck or two on the ground, but no ghost train.
Expand your moderator at work


pike
Premium,MVM
join:2001-02-01
Washington, DC
kudos:3

Re: How do railroad gates work?




lutful, I'm not sure I agree the firefighters share any responsibility for the accident. If I recall correctly they did shut down the malfunctioning loco and that probably was the cause of the brakes bleeding off and the train running away. But if the engineer had followed SOP and set the appropriate number of handbrakes, it would not have mattered if the air brakes were held or not.
Expand your moderator at work


54067323

join:2012-09-25
Tuscaloosa, AL

1 edit
reply to pike

Re: How do railroad gates work?

said by pike:

But if the engineer had followed SOP and set the appropriate number of handbrakes, it would not have mattered if the air brakes were held or not.

Quite correct, that is the reason for tying it down, should the engine(s) cease running and the air bleeds off releasing the locomotives brakes, it in theory will still not move.

This is one I didn't follow, but is there any information determiniing if the conductor actually applied the locomotives and or cars mechanical brakes?