Difference between traffic light and semaphore.

From the first years of life, we teach children to cross the road only on a permitting signal. Fortunately, modern cities are equipped with a huge number of traffic lights designed to ensure the safety of all road users. The change of colors on the signal device acts as a guide for us to action. Another thing is the semaphore, which is something outlandish and unusual. Most people consider it to be an analogue of a traffic light, but installed not on a road, but on a railway. Is it really? Let's try to figure out how a traffic light differs from a semaphore.


Traffic light is an optical device that regulates the movement of pedestrians and vehicles (cars, trains, trams, river and sea vessels, etc.). The principle of operation is based on the supply of light signals. The history of the device is about 150 years old. The first traffic light was installed in the British capital near the parliament building in 1868. Since its creator was a specialist in the development of railway semaphores, the new device did not differ much from its prototype. Equipped with two movable arrows, it had manual control.

Traffic light

Traffic light signals were intended exclusively for vehicles and were used to ensure the safety of pedestrians. Traffic control in the dark was carried out using a rotating gas lantern, illuminated in red and green colors. In 1869, this element of the device exploded, causing shrapnel wounds to a police officer.

The first automatic traffic light with unlit Stop and Proceed was patented in America in 1910. As for the analogue of the modern tricolor device, it appeared on the streets of New York and Detroit ten years later. This innovation came to Russia only in 1930. The first traffic light was installed in Leningrad, the second, a few months later, in Moscow.

Semaphore is a stationary signaling device used on railways. It is a high mast with movable wings (from one to three) fixed on it, the position of which is a reference point for the driver. At night and in the absence of good visibility, red, green and yellow signal lights on the device light up. The latter, along with the lowered additional (second and third) wings of the semaphore, indicates the need to reduce the speed of the train.


The horizontal position of the upper indicator and the prohibiting red signal are a call to stop the vehicle. Whereas the main wing located at an angle of 135 degrees and the green "beacon" indicate that the path is clear. It is worth noting that railway semaphores were widespread in the USSR until the 1950s. In the second half of the 20th century, they were replaced by traffic lights. However, on some sections of the track, outdated instruments are still used.


As can be seen from the definitions, the considered signaling devices have a number of differences. To begin with, a traffic light is a more modern and versatile device for regulating traffic. It is used both on roads and railways and for signaling water transport. Whereas the semaphore is an obsolete device. Today only inactive industrial sections of railway lines are equipped with it. If traffic signals are distributed to all road users, then the semaphore is intended only for drivers. Depending on the position of the arrow, the locomotive driver takes certain actions or calmly continues the journey.

Another difference between a traffic light and a semaphore is in the design of the devices. The first is an optical signaling device. It consists of a housing and a lens head mounted on it, emitting light from LEDs or incandescent lamps. Signals are given around the clock. A semaphore is a mast with wings. The latter are used to provide visual cues. Illumination of indicators is switched on only in the dark and in poor visibility conditions. The rest of the time, it does not function.

To summarize, what is the difference between a traffic light and a semaphore.

Traffic light Semaphore
Consists of a body with a lens head emitting light from LEDs or incandescent lampsRepresents a mast with wings and additional lighting
Light signals are provided 24 hours a dayturns on only at night
Used both on roads, railways and on waterUsed only on railways
Signals apply to all road users (drivers, cyclists, pedestrians)Signs are intended only for drivers
It is a modern and versatile deviceIt is an outdated device, it is extremely rare