Off of what topic? All possible topics? This post is just me rambling and being curious about railroad signals. Internet search comes back with a few posts on Railroad Signalling. Searching this forum does the same. At least one post in "Off Topic" had the same list of Internet Documents that I found. I believe there would be no opposition if I asserted here that signalling authorities are indeed the Railroad Owners with some oversight from some safety board (which I didn't go in search of). My first impression was that of amazement that there exists one thing that the US government does not control. Railroad Signals. Since the US government let that go without forming a department around it, my quickly formed probable cause would be - they dont want to get blamed. Train wrecks are a media circus. Perhaps they own the aforementioned "safety board," thus allowing them to manipulate the outcomes while still remaining blameless. I dunno. My next impression was that of surprise regarding how much information gets conveyed through the signals. 100% of my train driving experience comes from Train Sim World 2, so I am quite confident in my knowledge that green means go, red means stop, and yellow means something interesting may or may not happen, but don't worry about it because the HUD is going to tell you what to do. The HUD knows all, and is the final authority. I have not looked up signalling processes from railroad operators/owners. At least, not so far since the most complicated signal configuration I had seen prior to Sherman Hill was a [yellow | green] over [red] with no understanding of why anyone would stick two different colored lights on the same pole. Sherman Hill is what awoke my curiosity, for two reasons. The first being their yellow and red lights blink from time to time. The second being, the signalling authority will give me permission to Proceed at Restricted Speed into a signal zone with a stopped train in it. I don't know what the space between signals is formally called, so, yeah - signal zone. That stopped train never moves either. Thus the train line operator/owner/authority is willing to leave the mainline clogged up for days/weeks. Union Pacific would not do that, but who cares, they don't matter. DTG is the signalling authority. Hence, I am proceeding- looking for DTG's signalling procedures manual - at minimum safe speed.
The reason is much more pragmatic than that. Over the course of the 20th century. each of over fifty Class One railroads developed its own signaling system. These were private concerns doing whatever suited them best; and since each only drove trains over its own tracks (usually), all an engineer had to know was his own RR's signals. Although the old horde of independent RR have now been consolidated down to 5 US plus two Canadian, they each maintain their own systems, in many cases multiple systems inherited from their merged predecessors. The biggest single reason the Federal Railroad Administration has not ordered a single unified system is that the expense of replacing the signaling across the world's biggest railway network would run into the countless billions of dollars.
