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Quiet Freight Trains

Except the Horns, Maybe
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We know how loud trains are, right? Where I live, freight trains regularly pass on a track 1.5 to 2 miles (2.5 to 3 km) away, but they can easily be heard clearly (not just the horn, the engine itself), even though we live in a fairly foresty place. That can't be a good thing.

The question is how to quiet them. There are a couple of solutions. Mufflers, loudspeakers that propagate sound waves 180 degrees out of phase, actual sound insulation in the engine room would all work, with varying degrees of effectiveness. Out of the three, I believe the first two to be the most likely to work, although it would be a hard thing indeed to find loud enough speakers to have any real effect. There are other ways, I'm sure.

galukalock, Apr 25 2003

go to the source http://www.gmemd.co...ght/sd70m/index.htm
[ato_de, Oct 04 2004, last modified Oct 05 2004]

[link]






       You must have been hearing nice trains. The trains where I live are nasty. An ugly horn (meant to scare the living daylights out of all things on or near the tracks), and the clunk is a massive rumble not unlike a tornado, but the worst part is the loud, unmuffled (so far as I know) engines themselves (often three or more pull trains here). Not nice here.   

       I like train whistles too, by the way. Steam engine sounds, too.
galukalock, Apr 25 2003
  

       Quite so, although I'm not sure the rumble is the *majority* of the noise. But I won't argue the point. What I'm after here is to quiet the engines themselves. They are, after all, at least a significant noise contributor, and the easiest to quiet. The engine noise bothers me more than the rumble, anyway.
galukalock, Apr 25 2003
  

       i don't think active noise cancellation works from the noisy end very well. that is... noise cancellation headphones work by analyzing the waves coming at the ear, therebyb automatically taking into account any local resonance, reflections or variations that the sound waves may be subject to on the way form the source to your ear.   

       by creating the "anti-noise" at the source, you cannot necessarily account for all the variations that might occur once the sound has travelled away from the engine.   

       not to mention that trying to determine the directionality of each source of sound form an engine and mounting a speaker so as to offer the exact same directionality would be a bit tricky...   

       no, i say engine insulation is the way to go. unfortunately, the only really good way to muffle low frequency sounds is by taking up a lot of space with a lot of heavy material. nothing beat two cinderblock walls with a foot of dead air between them. by adding all this weight to the locomotive, you'd probably need to up the power of the engine, thus upping the noise...
urbanmatador, Apr 26 2003
  

       Uh, yeah. What about something in a good muffler (is there a different word fer that in the UK?)?
galukalock, Apr 26 2003
  

       <Flashback - Cheap Motel Room - 1968 - 3:30 a.m./>

  

       #######(!!!!!!~ !!!!!!~ !!!!!!~ !!!!!!~ !!!!!¶(o)########
_________________________
__________
: o
: o
¯¯¯¯¯¯¯¯¯¯
__________
: o
: o
¯¯¯¯¯¯¯¯¯¯

</Flashback - Cheap Motel Room - 1968 - 3:30 a.m.>
thumbwax, Apr 26 2003
  

       trouble with a muffler (like on a car) is that the muffler only muffles the sound that would otherwise be emitted from the tailpipe of the car. an engine is making a whole bunch of explosions all the time and that sound is traveling along the same path as the exhaust.   

       the diesel engine on a train is making a great deal of noise besides the noise that comes out the exhaust vents which are, i assure you, already muffled.
urbanmatador, Apr 26 2003
  

       That's very good ASCII art, [thumbwax] - beautiful.

I quite like freight trains, especially the mile-long ones you have in the US.
[galukalock] - isn't the problem really that the freight trains near you make the wrong sorts of noises? It's going to be much cheaper to fit the trains with old fashioned whistles and change the clunky noises to slightly different clunky noises than it will be to silence them.
hippo, Apr 26 2003
  

       The idea isn't to silence them per se, just make them quieter. As I said earlier, the best way to go about it would probably be to use some kind of muffler on the exhaust.   

       [urbanmatador] Nothing personal, but I don't believe you. Gimme a link that says they already have mufflers.
galukalock, Apr 26 2003
  

       There isn't a universal true answer. Train exhaust systems vary greatly with those intended for switchyard use requiring both exhaust and intake muffling, others that are turbocharged having no mufflers, but nearly all having some sort of exhaust spark arrestor system.
bristolz, Apr 26 2003
  

       Yes, that's funny.   

       Okay, now we knowing that some are to having some kinds of a muffler, but for surely just in Russka. Some of a company in American United Statehoods is making mufflers for American Diesel Engines, but none showing if those engines for fact use the mufflers. What is certainly is, the mufflers could to be making improved in design, in cause for better noises absorbing.
galukalock, Apr 26 2003
  

       Eh?
bristolz, Apr 26 2003
  

       Freight planes. That's right, 50 planes attached at the ends, flying through the air. Quieter. Faster. Making the world a better place.
phundug, Apr 27 2003
  

       How in heck can there the 4 fishbones to one croissant?   

       I once bought a home sorta near some tracks. In all the times I visited there was not a single train.   

       Then the first night we moved in, at 2 am there was a great thundering and the house shook as a beast of a train thundered through. Seems the track only functioned at night.
FloridaManatee, Apr 28 2003
  

       Lay the track in such a way that when passing a residential area, the train runs up and over a parabolic "hill" of such shape that at the right speed, the train is nearly weightless (not totally though, otherwise it would leave the track) - this should reduce the rumble factor a bit.
friendlyfire, Apr 28 2003
  

       //by adding all this weight to the locomotive, you'd probably need to up the power of the engine, thus upping the noise...//   

       Locomotives need to be heavy. While I don't know if they have added ballast, they are hardly designed to minimize weight. Removing some weight and adding sound dampening would not be unreasonable.   

       That being said, I think the reason this idea is getting fishboned is that the author is basically saying "I hate loud trains and think it should be possible to quiet them" without offering any particular original insight as to how that should be achieved.
supercat, Apr 28 2003
  

       Well, I did try to. I mentioned sound cancellation, dampening, and mufflers (or better mufflers if they already have them). It seems hardly anyone paid attention to that part.
galukalock, Apr 29 2003
  

       //Well, I did try to. I mentioned sound cancellation, dampening, and mufflers (or better mufflers if they already have them). //   

       Do you seriously think that the companies who build locomotives haven't already thought of such things?   

       If you were to suggest something a bit different, such as having the locomotive contain a large bank of batteries which would be charged when the train is in the middle of nowhere, and which could power the locomotive when it's in a residential area, that might be less likely to get fishboned. Not because it would necessarily be practical (batteries aren't terribly efficient) but because it would mark something which AFAIK railroads haven't tried to do.
supercat, Apr 29 2003
  

       What's in it for the railroad companies?
thumbwax, Apr 29 2003
  

       Ditto. Just the engine noise, please.   

       [cat] Quite so. I mentioned those particular methods as examples, not strict laws. There are a number of ways this could be accomplished feasibly.   

       [wax] If the railroads weren't as noisy, land values in the area would quite probably rise, if only a little. Multiply that little bit ($100 per acre, say) times all the residential zones near railroads (500,000 acres, to be conservative), and that's a substantial increase in taxes, even with the small numbers here. I'm sure some kind of deal could be struck with the government. If not, laws could always be made. Similar laws are already in effect for cars. That's one reason they have mufflers.
galukalock, Apr 29 2003
  

       Ouch.   

       //Usually, it's a wheel or two out of alignment//   

       I thought it was a flat spot on the wheel. No matter. They still sound terrible.
galukalock, Apr 30 2003
  
      
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