decibles

[wandasiem]

Has anyone measured the decibles of the train whistle which is blown as the train goes through protected crossings?

 

[battalion51]

Frikin loud. :lol: A lot of it depends on the Engineer and how hard he sounds the horn at a crossing. Some give it a few short taps, a few lay on the horn like there's no tomorrow.

 

[MrFSS]

I saw, from my train window last week, approaching a town in Virginia, a little sign the engineer would see and it said, "Thanks for blowing softly!"

 

[battalion51]

It just occured to me I have access to a decible meter through school, I'll see if I can borrow it for a weekend and do some measurements.

 

[gswager]

It's about 90-95 decibels in close range.

 

[A-Nonny-Moose]

TITLE 49--TRANSPORTATION

CHAPTER II--FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF

TRANSPORTATION

PART 229--RAILROAD LOCOMOTIVE SAFETY STANDARDS--Table of Contents

Subpart C--Safety Requirements

Sec. 229.129 Audible warning device.

(a) After August 31, 1980, each lead locomotive shall be provided

with an audible warning device that produces a

minimum sound level of 96db(A) at 100 feet forward of the locomotive in

its direction of travel. The device shall be arranged so that it can be

conveniently operated from the engineer's normal position in the cab.

(B) Measurement of the sound level shall be made using a sound level

meter conforming, at a minimum, to the requirements of ANSI S1.4-1971,

Type 2, and set to an A-weighted slow response. While the locomotive is

on level tangent track, the microphone shall be positioned 4 feet above

the ground at the center line of the track, and shall be oriented with

respect to the sound source in accordance with the manufacturer's

recommendations.

© A 4dB(A) measurement tolerance is allowable for a given

measurement.

 

[AmtrakWPK]

To be meaningful, and to provide a means to uniformly measure and compare, it would indeed have to be measured at a particular spot with reference to the engine. Sound, like light, generally follows the "inverse square law", which says that the intensity varies inversely with the square of the distance. In other words, the sound intensity at twice the distance would be 1/4, the intensity at three times the distance would be 1/9, the intensity at 5 times the distance would be 1/25, and so forth. This would be without regard to intervening obstacles or things like a dense patch of trees that would soak up the sound in that direction. You would assume they would want a higher level of sound in the direction of travel, and since (I believe) non-Genesis engines generally can be used running in either direction as lead engine, I would expect a sound peak at each end of most engines (not equal to each other, probably, but at a higher level than off to the sides). A polar plot of an engine's horn SPL would be interesting to see.

 

[GG-1]

Aloha

Was surprised about the 96db untill I reread the message. Most db test are done at 10 feet. I expect that at that distance the reading would be close to 150db.