How many decibels is a modern commuter diesel train at 100 feet away?

Question

A disused trainline passes 100 feet behind our house that may soon be used for a new commuter diesel train. Is there any research showing the decibel levels at 100 feet away of a modern diesel train or light rail at this distance running at ~30mph.

Links to any detailed research showing actual db levels of commuter diesels or light trail trains will get your answer ranked higher. Interested in the facts (not the politics).

Answer 1

The fact is, the train can run all day by your house with no noise pollution from the whistle at all.  If there are no grade crossings within 1/4 mile either way from your house, it's doubtful the whistle will be sounded at all unless in an emergency situation, as a practical matter.

In actuality, sound waves propagating through the air are affected by the parameters surrounding, temperature, humidity, barometric pressure and any wind that may be blowing.

But, there is a theorem called the "Inverse Square Law", whereby the sound pressure level drops off exponentially as distance from the source is increased.  Double the distance once, the level drops off by 1/2, again, 1/4, again 1/16th, 1/32nd and so on.

There are levels specified by the FRA but in practice where there is error it is on the high side.  Whistles can disturb conversation abd sleep but save lives.  If your question is beyond that of curiosity, as mounting a campaing to silence the whistles, it is very hard to do.  It is also my opinion that it is foolish.

Answer 2

If there is a crossing anywhere within a mile or so, you're going to get far more disturbed by the train's whistle (horn).  If it's relatively flat, you might barely hear the diesel engine, and most of the noise will be from the train cars.

Answer 3

The decibel level is only half the story because it depends on how long the noise lasts.  A fast train passing is only a few seconds.  A station stop will be longer and will certainly involve whistles.  A layover yard will involve sustained idling and switching.

I know somebody who lives in an old train station location RIGHT next to the tracks.  But he says he sleeps through the trains (freight) at night.

Answer 4

About 100 db