Rail Noise Question

[6 Lexington Ave]

I have a question which may seem weird. I've noticed, in some stations, weird noises coming from the rails even when trains aren't entering or leaving. These noises are basically metallic sounds like something moving on the rails. It's really noticeable at Bedford Av on the   . Any thoughts?

[realizm]

To start, assuming that the rails are an alloy of steel of some sort, generally metals are a good conductor of sound. So a train even from say 800 ft away from (or twice that now that I think about it)  the platforms (either before arriving or after departing) where the rail shoes and the wheels are hitting the rails will travel large distances and can be heard from far away. Also the vibrations of the spikes (for lack of a better word) on the ties attached to the rails can be heard as sound again travels pretty well from long distances. Or a switch in motion.

 

This is apparent on the at Bay Ridge Ave as well I've noticed. I've wondered about this myself and I think that is the reason.

[4P3607]

I remember a while back someone posted about this, they said it sounded like "Lasers being shot". I think it may have to do with the type of rail, I may go investigate this myself. It seems interesting how some stations you hear that noise, and other stations you don't.

[Via Garibaldi 8]

I've heard it also in some stations... Sounds like a clacking noise, but I never bothered to think about it...  I mean why is this is so shocking? You have a bunch of tracks that have points in which trains have to switch tracks and so on so I guess that's why I never gave it much thought. I'm sure the clacking isn't just because of that situation though.

[Threxx]

When trains pass over insulated joints, this sound is noticeable. Insulated joints are the things that hold the rails together. (They're often painted red.)

[m7zanr160s]

I think I know what OP is talking about. It's a clacking noise you hear when there is no train in sight or near. Like something metal is clamping on to something else metal. I wonder if it has something to do with the power in the 3rd rail...

[CenSin]

Sometimes it might be the devices besides the tracks that serve to trip the trains, but they sound more like a machine expelling air.

[realizm]

I agree on that one CenSin. I saw it literally for myself many times. I'm thinking now there are many factors involved here and all of you highlighted it. We just need a transit worker now to confirm our observations and theories.

Remember the old trick they used during the 19th century in with the classic steam railroad networks where a person would put their ear on the rails to listen for an incoming train? With all the factors involved as mentioned by all of you and the fact that dense metal is a good conductor of sound, aside from electricity and heat, that may be the reason for 6 Lexington Ave's observations.

 

 

I remember a while back someone posted about this, they said it sounded like "Lasers being shot". 

 

Yeah that's how it sounds to me aside from the clacking noizes as m7zanr160s was saying. 

[Quill Depot]

Yes the metal vibrates much. I really like those noises, as they really make the subway.

[PATCOman]

I think I know what he is talking about.  I hear it at 34th Street and 6 Avenue.

[itmaybeokay]

I remember a while back someone posted about this, they said it sounded like "Lasers being shot". I think it may have to do with the type of rail, I may go investigate this myself. It seems interesting how some stations you hear that noise, and other stations you don't.

 

Actually it doesn't sound like "Lasers being shot", but it sounds like what everyone's come to think lasers being shot sounds like - which is a pretty funny story. 

 

For the making of Star Wars, the sound designers needed a sound for the lasers and blasters and other fictional energy weapons would sound like. Using a real laser wouldn't be an option - as they generally don't make any sounds. 

 

The sound designers, to create that "pew-pew" we're all familiar with came up with a fairly novel solution: They attached microphones the guy-wires of a large TV transmission tower, and then struck the wires with a hammer. The impact sound on the long wire gave a sound that was perfect for the laser. 

 

Now, a rail is not much but a long, very thick, specially shaped wire. So, the bouncing up and down of several tons of train is going to travel down that wire and deliver a chorus of "laser sounds" to the stations before it. Especially with continuous welded rails. 

 

If you don't believe me, try it at home: You just need a plastic solo cup and a slinky.  take the plastic solo cup, jam it into one end of the slinky. Let the other end drop and hit the ground. The impact will radiate up the slinky, and the solo cup will serve as a poor-man's amplifier, making the pew-pew sounds audible. 

 

Here's part of the story as told by the sound designers father. http://filmsound.org/starwars/lasergunstory.htm

[Dan05979]

I've heard it also in some stations... Sounds like a clacking noise, but I never bothered to think about it...  I mean why is this is so shocking? You have a bunch of tracks that have points in which trains have to switch tracks and so on so I guess that's why I never gave it much thought. I'm sure the clacking isn't just because of that situation though.

I know that clacking noise your talking about. It sounds like 2 glass dishes hitting each other. I have no idea what that is. Probably just vibrations traveling thru the rails. That laser sound usually lets people know the train is coming. I always thought that was the electricity flowing thru the 3rd rail as the train was coming into the station. Like if the 3rd rail was "powering up"

[SubwayGuy]

I know that clacking noise your talking about. It sounds like 2 glass dishes hitting each other. I have no idea what that is. Probably just vibrations traveling thru the rails. That laser sound usually lets people know the train is coming. I always thought that was the electricity flowing thru the 3rd rail as the train was coming into the station. Like if the 3rd rail was "powering up"

 

If you're talking about what I think, that's the "insulator drop" which means a train is approaching. I'm not sure why or how it works, but it's been around for a while...people that walk tracks often (especially point to point) used to be trained to listen for it so they know to start clearing up.

 

Sometimes it might be the devices besides the tracks that serve to trip the trains, but they sound more like a machine expelling air.

 

The pneumatic stop arm motors (US&S signal associated stop arms) make that noise, it's a hiss when the arm comes up after the train leaves as the air forces the stop arm up.

 

If you hear a low mechanical growl, that's a GRS signal associated stop arm - those are electric.

[Around the Horn]

 

The pneumatic stop arm motors (US&S signal associated stop arms) make that noise, it's a hiss when the arm comes up after the train leaves as the air forces the stop arm up.

 

.

i always thought they sounded like opening a can of Pepsi...

[Via Garibaldi 8]

I know that clacking noise your talking about. It sounds like 2 glass dishes hitting each other. I have no idea what that is. Probably just vibrations traveling thru the rails. That laser sound usually lets people know the train is coming. I always thought that was the electricity flowing thru the 3rd rail as the train was coming into the station. Like if the 3rd rail was "powering up"

Yep, that's a pretty good description of it...

[realizm]

If you're talking about what I think, that's the "insulator drop" which means a train is approaching. I'm not sure why or how it works, but it's been around for a while...people that walk tracks often (especially point to point) used to be trained to listen for it so they know to start clearing up.

 

 

 

The pneumatic stop arm motors (US&S signal associated stop arms) make that noise, it's a hiss when the arm comes up after the train leaves as the air forces the stop arm up.

 

If you hear a low mechanical growl, that's a GRS signal associated stop arm - those are electric.

 

Good stuff. That pretty much answers the question in the OP. Case closed.

[dp142]

I've been a 3rd rail maintainer (Power Distribution Maintainer) for 19 years as well as a Track worker my first 2 years. On the job now 21 years total.

 

The older porcelain insulators used to support the 3 rd rail (Contact rail) have metal caps on them between the the 3rd rail and insulator. Once the tie that the insulator is on is no longer as snug as it used to be due the rail road tie or plate on the tie sinking or the insulator breaking the cap becomes loose. Once a train is a few stations away and starts drawing heavy  current on the 3 rd rail the caps magnetize and get pulled up to the 3 rd rail. That's the clacking sound. Usually you'll hear it more then once. Once the train stops drawing strong current in that area they'll drop again.

 

It should become less common as porcelain is being replaced by fiberglass.

[CenSin]

i always thought they sounded like opening a can of Pepsi...

Better description

[Dan05979]

I've been a 3rd rail maintainer (Power Distribution Maintainer) for 19 years as well as a Track worker my first 2 years. On the job now 21 years total.

 

The older porcelain insulators used to support the 3 rd rail (Contact rail) have metal caps on them between the the 3rd rail and insulator. Once the tie that the insulator is on is no longer as snug as it used to be due the rail road tie or plate on the tie sinking or the insulator breaking the cap becomes loose. Once a train is a few stations away and starts drawing heavy  current on the 3 rd rail the caps magnetize and get pulled up to the 3 rd rail. That's the clacking sound. Usually you'll hear it more then once. Once the train stops drawing strong current in that area they'll drop again.

 

It should become less common as porcelain is being replaced by fiberglass.

Thanks for that explanation!

[realizm]

Indeed! Thank you for breaking it down along with SubwayGuy, dp142! Honestly I was stumped by this for years as a straphanger.

[dp142]

The Pepsi can sound is the signals. 

Some of the trip arms located at the signals are air controlled whereas others are electric

[SubwayGuy]

I've been a 3rd rail maintainer (Power Distribution Maintainer) for 19 years as well as a Track worker my first 2 years. On the job now 21 years total.

 

The older porcelain insulators used to support the 3 rd rail (Contact rail) have metal caps on them between the the 3rd rail and insulator. Once the tie that the insulator is on is no longer as snug as it used to be due the rail road tie or plate on the tie sinking or the insulator breaking the cap becomes loose. Once a train is a few stations away and starts drawing heavy  current on the 3 rd rail the caps magnetize and get pulled up to the 3 rd rail. That's the clacking sound. Usually you'll hear it more then once. Once the train stops drawing strong current in that area they'll drop again.

 

It should become less common as porcelain is being replaced by fiberglass.

Excellent. Never knew the mechanics of how that worked until now. Thank you.

[Trainmaster5]

I've been a 3rd rail maintainer (Power Distribution Maintainer) for 19 years as well as a Track worker my first 2 years. On the job now 21 years total.

 

The older porcelain insulators used to support the 3 rd rail (Contact rail) have metal caps on them between the the 3rd rail and insulator. Once the tie that the insulator is on is no longer as snug as it used to be due the rail road tie or plate on the tie sinking or the insulator breaking the cap becomes loose. Once a train is a few stations away and starts drawing heavy  current on the 3 rd rail the caps magnetize and get pulled up to the 3 rd rail. That's the clacking sound. Usually you'll hear it more then once. Once the train stops drawing strong current in that area they'll drop again.

 

It should become less common as porcelain is being replaced by fiberglass.

Thanks for the clear, concise explanation. Very informative and should put an end to some of the speculation (humorous) posted earlier in this thread. Welcome to the forums and feel free to correct any mistakes I or others may put out. I try to learn something new every day and today your post did that. Carry on.

[m7zanr160s]

I've been a 3rd rail maintainer (Power Distribution Maintainer) for 19 years as well as a Track worker my first 2 years. On the job now 21 years total.

 

The older porcelain insulators used to support the 3 rd rail (Contact rail) have metal caps on them between the the 3rd rail and insulator. Once the tie that the insulator is on is no longer as snug as it used to be due the rail road tie or plate on the tie sinking or the insulator breaking the cap becomes loose. Once a train is a few stations away and starts drawing heavy  current on the 3 rd rail the caps magnetize and get pulled up to the 3 rd rail. That's the clacking sound. Usually you'll hear it more then once. Once the train stops drawing strong current in that area they'll drop again.

 

It should become less common as porcelain is being replaced by fiberglass.

 

Thanks for that explaination. I've been wondering about that for years.

[Culver]

I've been a 3rd rail maintainer (Power Distribution Maintainer) for 19 years as well as a Track worker my first 2 years. On the job now 21 years total.

 

The older porcelain insulators used to support the 3 rd rail (Contact rail) have metal caps on them between the the 3rd rail and insulator. Once the tie that the insulator is on is no longer as snug as it used to be due the rail road tie or plate on the tie sinking or the insulator breaking the cap becomes loose. Once a train is a few stations away and starts drawing heavy  current on the 3 rd rail the caps magnetize and get pulled up to the 3 rd rail. That's the clacking sound. Usually you'll hear it more then once. Once the train stops drawing strong current in that area they'll drop again.

 

It should become less common as porcelain is being replaced by fiberglass.

Excellent. Hear this a lot at Jay St-MetroTech on the track going south.