I've been working a lot with signals on the rapid transit side of things lately, and in my free time, am trying to learn how things work over in freight. I have a few questions.
We all know that signal spacing is determined by stopping distance. On the RT end of things, train length/weight basically don't matter because each car has its own braking apparatus, but on freights this isn't the case, which then suggests that there must be some length/tonnage limit for trains transiting a given line. That much makes sense to me, but I guess my question comes in areas with old signals today handling 10k+ freights -- how does that work? Do DPUs become mandatory?
These are disorganized questions; all answers are appreciated. Happy new year!
We all know that signal spacing is determined by stopping distance. On the RT end of things, train length/weight basically don't matter because each car has its own braking apparatus, but on freights this isn't the case, which then suggests that there must be some length/tonnage limit for trains transiting a given line. That much makes sense to me, but I guess my question comes in areas with old signals today handling 10k+ freights -- how does that work? Do DPUs become mandatory?
These are disorganized questions; all answers are appreciated. Happy new year!