Railroad Signals And Communication: A Retrospective!

The Norfolk Southern Corporation, a name all railfans are familiar with, has gone ahead and put together something pretty cool for us to view on their official youtube channel!
Allow us to share with you Communications Signals: Then and Now!
Communications and signals are the backbone of any railroad, and without those two things, train running would be utter chaos and near impossible. So it is then important to not only observe and respect the required communications and signals, but to understand how they have evolved over the last 100 years!
From rail road signals to hump yard retarders this video covers everything!
Knowing these rules and standard operating procedures, as well as knowing about the equipment and technology used to facilitate these procedures is key to a better future for the railroads, to ensure a safer and more efficient experience, whether it be for passengers or freight!
What changes do you think were most significant over time? We’d love to get your opinions on the matter!