Train noises are in the frequency of 400-4000 Hz [14] . ... Mobility of people has significantly increased. Daily and occasional trips consume a significant time in our whole life span. A comfortable and safe travel is prime need of any individual.
Under the Train Horn Rule (49 CFR Part 222, issued on August 17, 2006), locomotive engineers must begin to sound train horns at least 15 seconds, and no more than 20 seconds, in advance of all public grade crossings.
A calliope (see below for pronunciation) is an American and Canadian musical instrument that produces sound by sending a gas, originally steam or, more recently, compressed air, through large whistles—originally locomotive whistles.
If you hear, two small horns, it means the motorman is asking the guard to direct the railway signal to start the train. In case you hear three smaller horns, it suggests that the motorman has lost control over the train. This also acts as a signal to pull the vacuum break immediately. This signal is rarely heard.
Anyway, don't blame the engineer: They're required to blow that horn. The regulation in question is called the Final Rule on the Use of Locomotive Horns—a name that strongly implies they've had just about enough of your bitching—and it requires four blasts 15 to 20 seconds before every crossing.
120 – 140 decibels: Such as, a rock concert, auto racing, or a hammer pounding a nail. 125 – 155 decibels: Like, firecrackers or fireworks, or a jet engine. 170 – 190 decibels: For example, a shot gun blast or a rocket lift off.
However, it has no connection to Morse code other than coincidence. Train whistles have been around for over a century (much like Morse code) and have been used to transmit information to the conductor in the caboose as well as to others that may need to hear it.