OK, we're getting a little off kilter here and most of it is my fault, so let's see if I can clarify...
Catenaries:
As mentioned in earlier posts, all main (inside) catenaries and buffer catenaries are controlled by operators within the S&I facility. Everything outside (everything other than mentioned here...) is controlled by "others", presumably at a master desk somewhere. I don't know how many circuits are in the yard proper, but someone somewhere certainly has control of those, too.
Occasionally I mentioned "buffer" (slang term) when I should have stated "buffer catenary" (correct). In the course of construction, folks sometimes shorten to get to the point more quickly and the shortened terms become the de facto descriptions. If you see "buffer", it means "buffer catenary".
The S&I facility has two tracks and operation of Track 1 is identical to that of Track 2, however either track can be operated independently of the other. For example, Track 1 can be in use and (at the same time) Track 2 can be out of service for maintenance activities.
Each track has three catenary sections: the main (inside) catenary and two buffer catenaries, one at the east end and one at the west.
Each buffer catenary is approximately 80 feet long - that's just a rough guess, but for the purposes of discussions here, it will do and keep the math simple. With the big red doors closed, about half is inside and the other half outside, so that's around 40 ft. either side of the doors.
The main (inside) catenary runs almost the full length of the building, right up to the buffer catenaries on either end. Somewhere I have a CAD model of the building, but it's about a 1/4 mile long. So if I tell you it's a 1/4 mile long, that makes the main (inside) catenary about a 1/4 mile long minus 80 feet. Everyone with me?
All six catenary sections (three on either track) can be operated independently of each other, however operation of any portion is mechanically and electrically interlocked so that inadvertent operation is not permitted, i.e., you can't just walk up to a pushbutton on the wall and say "hey, I wonder what this does..." - more on that later.
The term "dead zone" is slang and means different things to different people, therefore I do not use it.
Each of the six catenary sections are either "de-energized" or "energized" depending on operations (see below).
Train Doors:
Again, a term no one really agreed on, but it stuck. "Train Doors" are the big, dark red folding doors that open and close to permit trains to enter and exit the building. Seems simple enough, doesn't it? But of course, some folks think "doors on a train..."
The door manufacturer had its own terminology and a lot of design documents referred to them as "bi-fold doors" (in fact, they are two piece and they do fold in the middle...), but that didn't stick either. One of the reasons is that in the discussions regarding (eventual) facility operation, we needed to distinguish between "train doors" - the doors that let the trains in and out - and "man doors" (personnel doors), many of which were to be locked to restrict access. In any event, the term "train doors" stuck. If you said, "Track 2, east end man door" or "Track 2, east end train door" or "South side #4 man door to the parking lot", people knew what you were talking about.
Operations:
The train doors are mechanically and electrically interlocked such that each respective buffer catenary can be energized only when the train doors are fully opened - not cracked open to let in air, opened a foot to let someone out or opened halfway - they must be opened to their full extent of travel.
The corollary is once a buffer catenary is energized, the respective train doors cannot be closed - automatic and manual controls are disabled and cannot be overridden. You can probably yank on one with a forklift all day, but you'd break a lot of stuff first.
So, the train doors don't "close on a live wire" - sorry, just doesn't happen.
The normal (very abridged) operating sequence for running trains in and out of the S&I facility is as follows:
Let's assume there's a train set in the building and you want to let it out. The following tasks are performed in order:
1. Energize main (inside) catenary
2. Open train doors
3. Energize buffer catenary
4. Retract derails (derails "off")
The train set may now exit the building. Since everything is energized/open/retracted, you may also bring the next train set in for service. Once parked inside, just reverse the above (in order):
1. Advance derails (derails "on")
2. De-energize buffer catenary
3. Close train doors
4. De-energize main (inside) catenary
In another post, operation at an Amtrak Acela S&I facility was mentioned and it was noted that trains "coast" through dead buffers. That might happen at Amtrak - I don't know as I have no knowledge of their operation or their facility, although the facilities are of a similar design.
I can tell you that no one "coasts through dead buffers" at Morrisville - again, sorry, just doesn't happen.
I hope this clears things up a little bit. Everyone have a nice weekend and I'll have a few more pictures tomorrow.
