How Railroad Signals Prevent Collisions on Single Track Lines

How do railroad signals prevent collisions on single track lines? Learn how track circuits, blocks, CTC, interlockings and positive train control keep trains from meeting head-on. Two trains, one pair of rails, and no way to see around the curve. In this video, you'll see how railroads solved that problem, from a telegraph order in 1851 to computers that can take over the brakes. And you'll find out the one weak point that even the safest signal system can't fix on its own. What you'll learn: • Why single track railroads use passing sidings • How Charles Minot used the telegraph in 1851 to run trains • What dark territory is and how track warrants work • How a track circuit detects a train, and why it fails toward safety • What blocks and absolute block signals do on single track • How Centralized Traffic Control (CTC) changed railroading in 1927 • What an interlocking is and how it stops conflicting routes • What happened in the 2008 Chatsworth collision, based on the NTSB findings • How positive train control (PTC) works and what it prevents • What happened at Cayce, South Carolina in 2018, and why signal suspensions matter Chapters: 00:00 How do trains avoid head-on collisions on one track? 00:33 Single track railroads and passing sidings 01:37 1851: Charles Minot and the first telegraph train order 03:05 Dark territory and track warrants explained 04:25 How a track circuit works 05:35 Why railroad signals fail toward safety 06:25 Blocks and absolute block signals 07:55 Centralized Traffic Control (CTC) in 1927 09:25 Interlockings: how conflicting routes are stopped 11:05 Chatsworth 2008: a head-on crash on a track with signals 12:35 Positive train control (PTC) explained 14:05 Cayce 2018: where the safety net had holes 16:05 The weak point and the layered answer 17:15 Where PTC and dark territory stand today 18:05 Watch next: Why Are There Rocks Under Railroad Tracks? Watch my previous video: Why Are There Rocks Under Railroad Tracks? If you like learning how railroads really work, please like this video, subscribe, and turn on notifications so you don't miss the next one. Tell me in the comments: what's the strangest thing you've ever noticed on or around a railroad? A weird signal, a strange box, a part you couldn't explain? The most interesting story will be the topic of my next video. Know someone who's obsessed with trains? Share this video with them. Sources: National Transportation Safety Board, Federal Railroad Administration, Congressional Research Service, and railroad history references. #railroadsignals #trains #railroadsafety