Railroad Semaphore Signal

Semaphore is one of the earliest signal systems adopted by railways in England. It was and, in some cases, still is, used on railways around the world.

Semaphore went into wide use in England in the 1840s. Railroad semaphore is a signal that tells the engineer or engine driver that the line ahead is clear or whether the engineer should slow down or stop the train. This is an important safety device that prevents trains from colliding.

Trains, unlike cars, take a longer distance to stop. The average length of a freight train is between one to two miles and if that train is traveling at 55 miles per hour it would take about a mile or sometimes more (depending if the consist was empty or fully loaded) for the train to come to a complete stop. Therefore semaphore signals are essential to let the engineer know what dangers may lay down the tracks or around the bend.

These signals vary in design but they basically have a flag arm or blade that conveys a signal to an approaching train. The arm is positioned straight up, at a 45 degree angle, horizontal, or straight down. The blade is most often painted red with a white strip.

By the 1870s, the semaphore signal was in use by most railroads in the United States.

Later designs added signaling lights (red, yellow, green). Eventually the blade was dropped in favor of signaling lights alone. Now the majority of semaphore signals are gone on the rails of the United States’ main lines.

There still are a few semaphore signals in use in the United States such as on the BNSF’s Glorieta Subdivision in New Mexico. This route is still used by the Amtrak route the Southwest Chief (Chicago to Los Angeles).

The anchor for the sketch was a field sketch I did of the semaphore signal at the Colma History Museum. One of the things I really love about sketching is that you continually learn about the things you are sketching and just doing the sketch of the semaphore signal maybe made me wonder about its origins, designs, and its current status. The remainder of the spread is the byproduct of that wonder.

The layout of this spread has a satisfying and balanced feel. You have the high and low vertical elements of the semaphore signals in “stop” position and the use of triads. I would like to say that I planned this out by doing a pre sketch but this spread developed organically over time. The human eye, at least my human eye, likes repeated patterns and balance. And sometimes these designs happen without cognitive thought. It’s like each element of the sketch falls in place finding it’s own angle of repose.

A semaphore signal at the Colma History Museum. The signal is in the “Stop” position.
Two semaphore signals in Niles Canyon near the Sunol Depot. This shows off two different styles of semaphore blades, square and fishtail.

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