QUOTE: Originally posted by amtrak-tom Thanks for all of the replies. I do understand interlockings, it's the diamonds I wasn't sure about. I do find diamonds interesting!
QUOTE: Originally posted by M.W. Hemphill CTC is an outgrowth of the Absolute Permissive Block system of operating automatic block signals, which was a two-way method of running, and beneath that rests the track circuit. The CTC machine sits on top of an APB signaling system -- to this day -- and gives the dispatcher the ability to prioritize traffic, by selecting the direction of the current of traffic, and the position of switches. But the dispatcher merely requests -- the CTC/APB system decides if it is safe or not, using its track circuits, and grants a request after it has checked.
Carl
Railroader Emeritus (practiced railroading for 46 years--and in 2010 I finally got it right!)
CAACSCOCOM--I don't want to behave improperly, so I just won't behave at all. (SM)
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
QUOTE: Originally posted by M.W. Hemphill Mud: A Santa Fe dispatcher friend (refuses to call himself BNSF) says the crossover frogs on the transcon are welded every two weeks minimum, some of them every 10 days. What's it take to weld a frog in your experience? I recall it was an all day project for a universal crossover for a welder and a helper. And people wonder why the second track is necessary ...
"We have met the enemy and he is us." Pogo Possum "We have met the anemone... and he is Russ." Bucky Katt "Prediction is very difficult, especially if it's about the future." Niels Bohr, Nobel laureate in physics
QUOTE: Originally posted by jeaton Mudchicken Do you mean to tell me that spikes aren't manganese??[:O][:O][:O] Jay
QUOTE: Originally posted by tree68 Seems like I recall reading once that on DE locos it was necessary to throttle down when crossing a diamond. The purpose was to minimize the possibility of arcing of the traction motors. Still true?
QUOTE: Originally posted by M.W. Hemphill I'd need to know the exact sequence and where the train is at the same time. Is the signal you're looking at an absolute or an intermediate? Intermediates have number plates on them, and are not controlled, but automatic only. For an absolute, after the train is past, if the signal reverts to a red aspect and stays that way even after the train has passed several more block signals, then the dispatcher has lined up no following movement -- or has lined up an opposing movement on the same track. If it progresses from red to more favorable aspects, then the dispatcher has lined up a following movement.
QUOTE: Originally posted by M.W. Hemphill Umm ... From UP829's description, he's looking at an absolute protecting the entrance to a control point. Some notes: In this territory, these absolutes are controlled (by the dispatcher). A signal with a number plate is an automatic signal; it is never controlled. An absolute might be controlled, but there are lots of uncontrolled absolutes -- such as at a manual interlocking, or the leaving signal off a spur onto a controlled track. Absolute means you cannot pass it when it's red without verbal authorization from a dispatcher or control operator. A red intermediate is a "stop and proceed at restricted speed." Absolute signals authorize main track occupancy. Intermediate signals do not. Both advise of track conditions ahead. Apparently these are not approach-lit signals, if they're lighting before the approaching train hits the previous block.
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