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UNDERSTANDING THE LANGUAGE OF THE TRAIN WHISTLE

a steam engine is sitting on a train track

There are so many sounds that we associate with the train: the rumble of the engine; the click-clack of the wheels along the tracks; the screech of the brakes; but maybe the most popular, the choo-choo of the train whistle.

The train whistle is the universal sound of the locomotive. But did you know that these sounds are actually a series of codes that train engineers used to communicate with other railroad workers?

Let’s explore the significance of these familiar blares and how to interpret what they mean.

History Of Train Whistles

The invention of the first train whistle dates back to the mid-late 1800s. It was developed by an engineer named Adrian Stephens, who created the device as a safety tool to warn pedestrians and other locomotives that a steam engine was approaching.

It wasn’t long after that many railroad companies started to use these whistles in patterns, creating a set of recognizable codes to communicate with their teams. The only problem: each company had its own set of train whistle codes.

With the risk of railroad crashes and incidents still looming, the General Code of Operating Rules introduced a uniform system for all companies to follow.

Standardized Train Whistle Meanings

In the United States, there are 2 primary train whistle sounds:

  1. The long blast: a single whistle that lasts at least 3 (and sometimes up to 10) seconds.
  2. The short blast: a single sound that lasts no longer than 2 seconds.

Using combinations of the long and short blasts in different patterns allowed railroad operators to communicate with each other more efficiently, especially over large distances. The chart below outlines some of the common combinations and what they mean.

Train Whistle Signals Chart

In the General Code of Operating Rules, whistle signals are illustrated as the following:

  • “O” for short whistle blasts
  • “—” for long whistle blasts.

 

Whistle Code Sound Meaning
O O O O O O A succession of short sounds There is an emergency; livestock is on the track, possibility of train derailment, etc. Do not proceed.
O O 2 Short Blasts Acknowledgment of any signal.
O O O (When the train is stopped) 3 Short Blasts The train is backing up.
O O O (When the train is in motion) 3 Short Blasts Another acknowledgment of any signal.
O O O O 4 Short Blasts The signal is not clear; another signal is requested.
— 1 Long Blast The train is approaching a station.
— — 2 Long Blasts Release the brakes, the engine may proceed.
— — O — 2 Long, 1 Short, 1 Long Blast The train is approaching a crossing grade
— O  1 Long, 1 Short Blast The train is approaching men or equipment on the tracks; must sound even in prohibited areas.

Train Whistle Regulations

The tone of the train whistles can carry up to several miles away from where they are sounded. This is great for railroad workers, but not so great for families working or living in areas surrounding active railroad tracks.

In response, whistle quiet zones were created. These zones help reduce the noise pollution from trains during designated hours of the day.

Today, most of the train whistle signals listed above can be replaced by other forms of communication, except for the 3 we’ve highlighted in red. These train whistle codes are still extremely common and important to the safety of railroad operations. They are also an exception to whistle quiet zones and can be sounded during quiet hours in the case of an emergency.

Want to learn more about the unique language of trains? Check out our blogs on how to read railroad signals and railroad signs. 

A close up of a steam engine whistle and bell with smoke coming out.

Train Whistle FAQs

What Is The Meaning Of Train Whistles?

There was a long list of whistle sounds and their meanings after the General Code of Operating Rules standardized these blares. The 3 most common that are still used today are:

  1. O O O O O O: the succession of short blares, which indicates there is an emergency.
  2. — — O —: the long, long, short, long, which is sounded when the train is approaching a crossing grade.
  3. — O: the long, short, which is used to warn personnel that a train is approaching them on the tracks.

What Are Train Whistles Made Of?

In their early days, these whistles were made from cheap materials like brass or copper. Later on, stainless steel and brass became the standard.

How Does A Train Whistle Work?

After mounting these hollow, cylindric pipes on the steam train near the firebox, they rely on 3 factors to produce their sounds: steam, air, and vibration.

When the engineer pulls the lever to sound the whistle, the steam rushes from the boiler into the whistle box. The intense pressure of the steam causes it to escape through the small opening at the top of the whistle, which in turn decreases the pressure inside the chamber.

The lower pressure inside the box allows the outside air to enter back through that same opening. The steam and the outside air mixing is what creates the loud whistle sound.

How Far Can A Train Whistle Be Heard?

The distance that a train whistle can travel is dependent on many different factors. The type of train, how fast it’s traveling, and the environmental conditions can all impact how far the noise can be heard.

Generally speaking, most train whistles can be heard within a 1-3-mile radius of where it sounds.

How Many Decibels Is A Train Whistle?

According to the Federal Railroad Administration, train whistles have a minimum requirement of 96 decibels and a maximum level of 110 decibels.

Are Train Whistles Still Used?

Yes, train whistles are still a crucial part of maintaining safe railroad operations. The most important whistles include the succession of short blares; the long, long, short, long; and the long, short patterns.

Hear the whistle of an authentic steam train when you visit Strasburg Rail Road, America’s longest-operating passenger railway. Book your steam train adventure today!

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