I watch the Rochelle IL webcam almost every day, and I am amazed at the wide variety in the horns which warn the public that a train is coming! Some horns are quite melodious, beautiful in fact, and others are awful to listen to. All the horns perform their warning function well. My question is how are horns selected when an engine is built? Is it just randomly done, or is there an effort to make them pleasing to the ear? No two engines seem to have the same sound.
Some of the variety you hear is due to the fact that each railroad had its own “standard” for equipping air horns on the locomotives they ordered from the manufacturers. As these railroads were merged into one another, they didn’t bother to replace the “non-standard” airhorns on the inherited units unless they failed. As we get fewer and fewer railroads and more older locomotives retire, you will hear less variety.
It is true that horns are becoming more and more standardized, but since they are mounted on a locomotive subject to lots of vibration and shock from rough service, as well as out in the weather with the sun beating on them followed by snow and wind driven rain, they tend to lose their delicately tuned properties over time and do not necessarily get the tender loving care of the maintenance folk that would keep their sounds pristine.
Another consideration is which bells are facing which way. On cab units, all the bells usually face the front of the locomotive. On hood units, one or more bells usually face the rear of the locomotive, in case it has to run long hood forward.
Add to that the stuff mentioned before (age, wear, snow, etc) and you can end up with some interesting sounds.
Here’s a good site that may answer some of your questions further:
http://www.dieselairhorns.com/
There are plenty of examples there - including some that sound pretty sick…
It should also be noted that at one time there was a Canadian standard tuning (there may still be). The US has no such standard, AFAIK.
As long as we are talking about horns, does any RR use electronic horns other than the Alaska RR? They have the weirdest sound I’ve ever heard.
Not to sure Alaska RR uses electronic horns, all pictures show regular horn clusters on engines.
All major railroads use electronic bells now, and are actively replacing real bells with them but I’ve never heard of an electronic horn. Just watched a video of an ARR SD70MAC, and it had an air horn & electronic bell.
Sound levels from horns are set by federal regulation. The minimum is 96 dB, the maximum is 110 dB.
Your average 100 emergency vehicle electronic siren is about 120 dB. A 200 watt siren is about 130 dB.
So an electronic horn is possible, although I’d prefer something “breathier” than the usual police car “air horn” buzz.
That said, I think you’d see a move of the “horn” from the roof of the locomotive to something lower, and on each end of the locomotive, perhaps controlled by the position of the reverser, with an override. Speakers tend to be more directional, too. That might bode well for those who complain about the noise of the horns…
The bigger issue may be perception - would a speaker generated horn be perceived to be as loud as an air horn?
Your recolection is better than mine. It was an electronic bell that did not sound like a bell and not like a horn but it did get your attention. Thanks.
Electronic “bells” don’t sound like classic bells, but they can be made to have the tapering off sound/volume of a classic bell, which is a distinguishing characteristic. I’ve done it on a computer.
Federal Signal went to great lengths to duplicate the sound of their classic Q2B electromechanical siren in an electronic siren - and they came pretty close. But the discerning ear can still tell the difference.
A regular electronic siren is essentially a single “note” of varying frequency. The sound of an electromechanical siren has a lot more components (ie “breathier”) so is that much harder to duplicate. So, to, it would be for a railroad air horn, although I think someone may have done a decent job duplicating the Grover “Stutter Tone” horn we often hear on fire trucks.
One vendor has come out with what amounts to a sub-woofer for the siren. I believe it’s thought the lower frequencies may penetrate the sound-proofed interiors of today’s vehicles better.
Electronic train horns may well already be in use, and if not, they’re a possibility.
Never mind the corny music and the fast cuts, here’s a comparison of electronic vs mechanical bells from Youtube:
Sorry, Larry; I can’t help minding the “corny music”–I could barely hear the real bell and could not hear the imitation bell at all.
There still is; I believe it is a distinctive D-minor chord, specifically meant to catch the attention in the ‘right’ way…