What are semaphore signals?

Semaphore signals are a type of railway signal that uses a pivoting arm, or blade, to visually indicate to train crews whether they are permitted to proceed. The position of the arm conveys the signal indication. A horizontal arm typically indicates 'stop' or 'danger,' while an angled arm indicates 'proceed' or 'clear.' Semaphore signals were one of the earliest forms of railway signaling and were widely used before the advent of color light signals. They rely on mechanical linkages to control the position of the arm, often using wires connected to a signal box operated by a signalman. The color of the arm is also significant; typically, a red arm indicates 'stop' and a green or yellow arm indicates 'proceed' with varying degrees of caution. At night, colored lights are often displayed in conjunction with the arm position to enhance visibility. While less common on main lines today, semaphore signals can still be found on heritage railways, branch lines, and in some countries where they remain in active service. The simplicity and reliability of semaphore signals made them a vital component of railway safety for many years.