Bells and Whistles: Signaling

Bells and Whistles: Signaling. . Imagine if steam locomotives still ran through here. It would be so loud you might not hear the person next to you., Because of the noise, railroad engineers used bells and whistles to alert passengers and workers that a train was arriving at the station. Eventually, train whistles were replaced by horns. The conductor also used a set of standard whistles to tell passengers when to board the train and when the train was ready to leave. Whistles are still used at railway stations. Trains also have horns that the engineer sounds as they travel through the countryside. These horns warn town residents and drivers that a train is on the way. Two long blasts, one short blast, and one long blast mean the train is approaching a crossing., If whistles and horns tell passengers when it’s time to get onboard or when the train is leaving, how do engineers know it is safe to get underway? The railroads developed a system of signals that tell the engineers when it is safe to proceed and when they need to stop. The earliest signals were a form a semaphore. Later a system of signal lights was developed. With the invention of the telegraph, an interlocking signal system linked the signals with track switches and was operated from a control room.