So I was about to post a second volume of PRR Signaling Sounds to highlight the importance of preserving both audio and visual history, but then I realized that I had a couple of non-PRR clips sitting on the back burner that deserved to see the light of day.
The first two were captured at some former Boston and Maine intermediate signal locations (BM mileposts 162 and 150) on the current Guilford Rail System Freight Main Line. To the untrained ear they might sound a lot like the PRR signaling sound samples of cab signal code generators, and you would be right. However why would cab signal code generators be used on non-cab signaled territory? Well while the trains might not have been equipped with cab signal apparatus, the signaling department would use the 75, 120 and 180ppm codes sent through the rails as way to replace signal state wires on wayside poles.
When a signal location "heard" an Approach from the location ahead, it would know to display an Approach and transmit Clear. When it "heard an approach medium it would display approach medium and transmit Clear and when it "heard" a clear it would display Clear and transmit Clear. Hearing nothing would of course mean to display Stop and Proceed and transmit Approach. Later this technique would be updated with audio frequency signals instead of pulses of power frequency current, but at the time it was a clever way to use catalogue parts to eliminate costly pole lines.
Next we have a flashing Approach Limited signal at the 1950's vintage CP-LAUREL on the former Reading railroad Belt Line extension. A visit to the relay cabinet reveals a sound pulsing in rhythm to the flash of the signal, which of course indicates of an electro-mechanical flashing relay. nothing super fancy, but it is a lot more reliable than what one might have to blink their Christmas lights on and off.
Well, that's the extent of the non-PRR signaling sounds I have collected. Don't worry all your PRR fans. I'll be back soon with a second volume ;-)
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