An 'S' means a station is 1 mi ahead, and an 'X' means a grade crossing is coming up. If there's a number with the 'X' it's how many are ahead closer than 1/4 mile apart Caltrain signalling guide that's really useful: https://signals.jovet.net/rules/Caltrain Signal Rules.pdf
Not only are they helpful, but they're simply indispensable when operating on Sandpatch or Peninsula in TSW or any of the the others in TS.
Wait, there's more? Can you send me the others guides too? And yeah your guide was really helpful in Peninsula Corridor!!!
Thank you for the kind words. Just remember that my charts reflect the actual rules and practices of the given railroads; they're generally intended for railfans. They only apply to simulation games so far as the simulation permits, and only as well as the skill and intention of the simulated world's programmers. I only have two TSW routes, but what I've seen of them demonstrates some egregious non-prototypical signal behavior. This is not entirely surprising, because railroad signaling is a very-involved aspect (pun intended?) of railroading to begin with, and it's usually not a glamorous one. So, with all the other important details to focus on when making a train simulation game or route, it's easy for signaling to not get the attention it needs to be understood properly and made reliably accurate. As an example in complexity, CSX uses three different signal schemas across its territory. This happened because of business mergers and bankruptcies, attempts at standardization and at being unique, etcetera. The three systems are mostly similar, but the details can be tricky. Looking at my CSX aspect chart doesn't really help if you don't know which of the three systems applies at a given location. The same is also true with Caltrain, which uses two different schemas... and while many of the signals may look the same, the two systems are very different philosophically. Luckily, the Caltrain system boundaries between them are minimized, and clearly documented.
When it comes to understanding how US and Canadian signals work, I also highly recommend studying this page: Al Krug's Signals Explanation (internet archive)
