# Why do the new subway trains sound so weird? **URL:** \ **Category:** Factual Questions\ **Created:** [June 28, 2005, 1:35pm UTC](https://boards.straightdope.com/t/why-do-the-new-subway-trains-sound-so-weird/310186 "2005-06-28T13:35:26Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![Grievre](https://avatars.discourse-cdn.com/v4/letter/g/22d042/32.png) [@Grievre](https://boards.straightdope.com/u/Grievre)\ **Post date:** [June 28, 2005, 1:35pm UTC](https://boards.straightdope.com/t/why-do-the-new-subway-trains-sound-so-weird/310186/1 "2005-06-28T13:35:26Z")
The two newest subway car models used on the NYC transit lines have a very distinctive sound to them. The Bombardier New York City Transit R-142’s acceleration sound takes the form of 3 notes, always in the same order, that sound kinda like a violin: [video here](http://www.transitconnection.net/media/movies/r142-125st.AVI) On the other hand, the Kawasaki New York City Transit R-142A and R-143 cars have a very different sound, which is a lot louder: [video here](http://www.transitconnection.net/media/movies/r143-6av.AVI) Now, all of the other subway trains just have a single note that seems to correspond to the motor speed, but these cars emit frequencies that don’t seem to have any correlation to how fast anything is spinning, so what exactly are the mechanics behind these sounds? ---
**Author:** ![TheLoadedDog](https://avatars.discourse-cdn.com/v4/letter/t/35a633/32.png) [@TheLoadedDog](https://boards.straightdope.com/u/TheLoadedDog)\ **Post date:** [June 28, 2005, 1:48pm UTC](https://boards.straightdope.com/t/why-do-the-new-subway-trains-sound-so-weird/310186/2 "2005-06-28T13:48:52Z")
Not familiar with the NY subway cars, but my wild-arsed guess is that the trains with the steady note have “chopper control”, whereas the ones with the stepped note have “notch control”. To explain this, trains have a series of different speed settings, not so much like gearbox speeds in a car, but more analogous to a car which has a gas pedal which can only be held at say five different points, rather than an infinite number. _All_ trains’ motors tend to be of the notch variety, but “chopper control” gives the driver the illusion of an automobile-type infinite ratio. In a notch control train, the driver will go “ONE **clunk** TWO **clunk** THREE” and so on as she accelerates. In “chopper control”, the driver pushes the throttle forward, and the train goes into notch one for a bit, then starts “chopping” in a taste of notch two power, then a bit more, then it’s actually in notch two, then it “chops” in a little bit of three, and so on. This seems smoother. Of course this is a guess, but it sounds like the likely scenario. ---
**Author:** ![Grievre](https://avatars.discourse-cdn.com/v4/letter/g/22d042/32.png) [@Grievre](https://boards.straightdope.com/u/Grievre)\ **Post date:** [June 28, 2005, 1:57pm UTC](https://boards.straightdope.com/t/why-do-the-new-subway-trains-sound-so-weird/310186/3 "2005-06-28T13:57:34Z")
I’ve heard tell that one of the two models actually does have a physical gearbox (if you listen to the R143 video, after the initial pitch rise, you can hear the typical rise-fall sound effect of a multi-ratio vehicle). Also, from what I’ve read around, _all_ new york subway trains have 3 forward speed settings, labeled (for obscure reasons) “switching”, “series” and “multiple”. This seems odd to me, because the entire NYC subway runs on direct current, in which case can’t they just use a variable resistor? ---
**Author:** ![TheLoadedDog](https://avatars.discourse-cdn.com/v4/letter/t/35a633/32.png) [@TheLoadedDog](https://boards.straightdope.com/u/TheLoadedDog)\ **Post date:** [June 28, 2005, 2:03pm UTC](https://boards.straightdope.com/t/why-do-the-new-subway-trains-sound-so-weird/310186/4 "2005-06-28T14:03:59Z")
The pick-up is DC, but the traction motors are AC, so it goes through a rectifier(?) thingummy. I’m also having second thoughts about notch control as you say the cars are new, and notch control is pretty ancient. All I can guess is that the chopper control on some of the cars is not very smooth. [http://www.nycsubway.org/cars/r142.html](http://www.nycsubway.org/cars/r142.html) ---
**Author:** ![Grievre](https://avatars.discourse-cdn.com/v4/letter/g/22d042/32.png) [@Grievre](https://boards.straightdope.com/u/Grievre)\ **Post date:** [June 28, 2005, 2:07pm UTC](https://boards.straightdope.com/t/why-do-the-new-subway-trains-sound-so-weird/310186/5 "2005-06-28T14:07:36Z")
A rectifier turns DC -\> AC, to do it the other way you need an oscillator. ---
**Author:** ![TheLoadedDog](https://avatars.discourse-cdn.com/v4/letter/t/35a633/32.png) [@TheLoadedDog](https://boards.straightdope.com/u/TheLoadedDog)\ **Post date:** [June 28, 2005, 2:07pm UTC](https://boards.straightdope.com/t/why-do-the-new-subway-trains-sound-so-weird/310186/6 "2005-06-28T14:07:36Z")
I doubt the gearbox. That is very, very rare in rail. Gearboxes are used in some short Japanese trains that are diesel-hydraulic or diesel-mechanical, but for a 5 car electric subway train, probably not. Heavy trains don’t like mechanical linkages because you introduce clutch mechanisms and gawdnose what all. These trains are better suited to in-bogie traction motors with direct drive, as electric motors provide high torque even from a standing start. They may be _geared_, but not vartiably so. ---
**Author:** ![TheLoadedDog](https://avatars.discourse-cdn.com/v4/letter/t/35a633/32.png) [@TheLoadedDog](https://boards.straightdope.com/u/TheLoadedDog)\ **Post date:** [June 28, 2005, 2:08pm UTC](https://boards.straightdope.com/t/why-do-the-new-subway-trains-sound-so-weird/310186/7 "2005-06-28T14:08:40Z")
Oscillator. I knew that. 😃 **cough cough** ---
**Author:** ![TheLoadedDog](https://avatars.discourse-cdn.com/v4/letter/t/35a633/32.png) [@TheLoadedDog](https://boards.straightdope.com/u/TheLoadedDog)\ **Post date:** [June 28, 2005, 2:09pm UTC](https://boards.straightdope.com/t/why-do-the-new-subway-trains-sound-so-weird/310186/8 "2005-06-28T14:09:50Z")
Hang on. Yes, we’re going DC \> AC here. DC third rail pick-up and AC traction. ---
**Author:** ![Grievre](https://avatars.discourse-cdn.com/v4/letter/g/22d042/32.png) [@Grievre](https://boards.straightdope.com/u/Grievre)\ **Post date:** [June 28, 2005, 2:11pm UTC](https://boards.straightdope.com/t/why-do-the-new-subway-trains-sound-so-weird/310186/9 "2005-06-28T14:11:07Z")
Actually for some reason they usually call it an “inverter” which seems like an incorrect name… Anyhow, I’m really wondering why the 143’s pitch rises and then holds steady apparently independent from the actual rotation. What could cause that? ---
**Author:** ![TheLoadedDog](https://avatars.discourse-cdn.com/v4/letter/t/35a633/32.png) [@TheLoadedDog](https://boards.straightdope.com/u/TheLoadedDog)\ **Post date:** [June 28, 2005, 2:14pm UTC](https://boards.straightdope.com/t/why-do-the-new-subway-trains-sound-so-weird/310186/10 "2005-06-28T14:14:40Z")
I suspect it’s just lag. Being in the cab with drivers in Sydney (hang on, motormen for you NY types), you see them throttle forwards, and the pitch goes up, then there is delay as the speed of the train catches up to the new setting. In other words, the pitch represents power, not speed. Not very technical, I’m afraid, but I hope it explains it. 😃 Electric trains at full speed tend to be relatively quiet - well, quieter than you’d expect. ---
**Author:** ![Grievre](https://avatars.discourse-cdn.com/v4/letter/g/22d042/32.png) [@Grievre](https://boards.straightdope.com/u/Grievre)\ **Post date:** [June 28, 2005, 2:21pm UTC](https://boards.straightdope.com/t/why-do-the-new-subway-trains-sound-so-weird/310186/11 "2005-06-28T14:21:52Z")
Actually they’re called TOs here 🙂 But I’ve seen several recordings and it’s always a rise to that pitch at the same rate regardless of the train’s acceleration. ---
**Author:** ![Grievre](https://avatars.discourse-cdn.com/v4/letter/g/22d042/32.png) [@Grievre](https://boards.straightdope.com/u/Grievre)\ **Post date:** [June 28, 2005, 2:24pm UTC](https://boards.straightdope.com/t/why-do-the-new-subway-trains-sound-so-weird/310186/12 "2005-06-28T14:24:20Z")
> [@Grievre](#): > > Actually they’re called TOs here 🙂 > > But I’ve seen several recordings and it’s always a rise to that pitch at the same rate regardless of the train’s acceleration. Well, not always at the same rate, but the initial sound never goes above that pitch. It hits the pitch and then fades out and then you hear the secondary noise. ---
**Author:** ![TheLoadedDog](https://avatars.discourse-cdn.com/v4/letter/t/35a633/32.png) [@TheLoadedDog](https://boards.straightdope.com/u/TheLoadedDog)\ **Post date:** [June 28, 2005, 2:30pm UTC](https://boards.straightdope.com/t/why-do-the-new-subway-trains-sound-so-weird/310186/13 "2005-06-28T14:30:07Z")
That’s where it gets beyond my ken. I have a vague understanding of the process, but so vague that I’m not confident to try to explain it. I know that DC trains at least, as they approach cruising speed, get into all sorts of weird “weak field” stuff that makes my head hurt. We need **David Simmons** or one of our other sparky types to come along and put it in plain English. ---
**Author:** ![Mehitabel](https://avatars.discourse-cdn.com/v4/letter/m/8797f3/32.png) [@Mehitabel](https://boards.straightdope.com/u/Mehitabel)\ **Post date:** [June 28, 2005, 4:00pm UTC](https://boards.straightdope.com/t/why-do-the-new-subway-trains-sound-so-weird/310186/14 "2005-06-28T16:00:37Z")
The AC/DC thing is correct. My Dad is a keen amateur student of the subway and has been since the 40s–I’ll forward this thread to him and see if he has anything to add. BTW, the TO’s (train operators, can’t call them motormen anymore) find the whine the most annoying feature of the new trains. Otherwise, they like them a lot. The repair guys do find it annoying that they’re so computerized you can’t pop open panels and repair things with your hand tools, usually, but they’ve been pretty reliable. I remember people gasping with delight and walking around them (if it wasn’t too crowded) when they first arrived. ---
**Author:** ![Grievre](https://avatars.discourse-cdn.com/v4/letter/g/22d042/32.png) [@Grievre](https://boards.straightdope.com/u/Grievre)\ **Post date:** [June 28, 2005, 10:50pm UTC](https://boards.straightdope.com/t/why-do-the-new-subway-trains-sound-so-weird/310186/15 "2005-06-28T22:50:36Z")
The transverse cab is the most annoying feature for me ☹ ---
**Author:** ![TheLoadedDog](https://avatars.discourse-cdn.com/v4/letter/t/35a633/32.png) [@TheLoadedDog](https://boards.straightdope.com/u/TheLoadedDog)\ **Post date:** [June 28, 2005, 11:29pm UTC](https://boards.straightdope.com/t/why-do-the-new-subway-trains-sound-so-weird/310186/16 "2005-06-28T23:29:18Z")
The Sydney version of this is called the Millennium Train. It’s quite a handsome looking beast, but it is so high tech that there are cries of wasted money and over-engineering. It’s been a bug-filled introduction for this train, and it can’t run on some lines because it flips out the signalling infrastructure. It’s not popular with the drivers either because so much of the tech is shrouded in secrecy (corporate carry-on - I got monstered by security for taking a photo of the thing!) that they feel disconnected from the train. Unlike NY, the local drivers prefer the old trains with their “you can pop the hood and know what the bits are” feel to them. The Millennium Train is one of our first forays into AC traction (network is 1500v DC), and it has that constant violin sound (which I quite like). ---
**Author:** ![Mehitabel](https://avatars.discourse-cdn.com/v4/letter/m/8797f3/32.png) [@Mehitabel](https://boards.straightdope.com/u/Mehitabel)\ **Post date:** [June 29, 2005, 2:45am UTC](https://boards.straightdope.com/t/why-do-the-new-subway-trains-sound-so-weird/310186/17 "2005-06-29T02:45:56Z")
Yeah, looking out the front window is mostly a thing of the past. Most TO’s have removed the black curtain that’s supposed to block the view but the windows are polarized so the view is sorta psychedelic. I remember standing on Dad’s feet to be able to look out the front of the old R33’s. Anyway, Dad wrote me back! _Originally posted by Mehitabel’s Dad:_ > [@](#): > > Your explanation is correct. Those were some interesting posts, there! The sound is related to the current demand, not the track speed. Accelerating trains draw more current than cruising or coasting ones. The three major speeds, “Switching”, “series” and “multiple” come from the older DC traction controller terminology. “Switching” holds the equipment at a very low voltage and comes into play when cars are being coupled or must approach objects very slowly. “Series” comes from the long-used traction acceleration technique of pairing motors so that the maximum voltage that each receives is only half of the available voltage. Trolley cars or trams ascending long grades often run in “full series” so that the wheels will not slip nor the motors overheat. “Multiple” is a term used for “parallel”, in which all motors in the vehicle can receive the full available voltage. Top speeds are mandated by motor design and the fixed gear ratios. When a train is in series it wil accelerate automatically (while sensing its load) to full half speed. In parallel it will accelerate itself to full speed. High speed trolley cars in the United States often had “parallel shunt”, but you don’t want to go there! The subways don’t. Electric railway vehicles have gears, but they are fixed onto the axles and motor shafts and may not be “shifted”, as in an automobile. Some large American electric locomotives were geared for passenger service, others for freight. Almost all the Diesel Electric locomotives in use throughout the world have permanent gear sets on their electric motors that are designed for the tonnage and terrain of their particular railway divisions. > > The same was true for trolley cars or trams. Cars running on busy city streets would have motor sizes and gear ratios that were good for the street speeds and terrain of the area. Interurban trolley cars were geared to run at high speeds. Up through the 1940s the dominant sound of electric railway vehicles in subways was the contact between the smaller pinion gear on the motor’s shaft and the larger bull gear on the driving axle, both being “straight cut” gears. Starting in the 1930’s different types of gear cuts were employed so that there was a smooth sound, but always directly related to the vehicle’s speed. On the new New York City cars the gears are virtually silent. The DC to AC conversion under the electrical demands of acceleration provide the interesting new sounds. Ta-da! ---
**Author:** ![gotpasswords](https://avatars.discourse-cdn.com/v4/letter/g/c57346/32.png) [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)\ **Post date:** [June 30, 2005, 6:07pm UTC](https://boards.straightdope.com/t/why-do-the-new-subway-trains-sound-so-weird/310186/18 "2005-06-30T18:07:00Z")
Interesting new sounds, indeed. A few years ago, I had the misfortune to be on a San Francisco Muni streetcar that decided it was time for a break. While I’ve seen how newer light rail vehicles are being designed so their power conversion and motors make musically harmonious sounds, the Muni streetcars at that time (wretched things from Boeing Vertol) just made random notes, whirs and buzzes. The newer cars from Breda aren’t particularly melodious, either. Well, this particular car chose to break and instead of the usual buzz and whir it would make starting off, it just went OOOOOOOO! click \ OOOOOOO! click. \*Very \* loudly.