The other day I heard a reference to a Saw-By (?) meet, what are they, and why are they used?
I’ll leave it to someone else to describe what actually takes place during a saw-by. It’s a way of getting two opposing trains past each other when both trains are too long for the siding.
Carl, I think you are talking about a double-saw, from my understanding. Of course it should be remembered that terms, like hand signals can have different meanings in different areas, even on the same railroad.
A plain saw-by is one where the train taking the siding is too long to clear up. The one on the main will fit between the switches. When it arrives, the train in the siding pulls out on the main until the rear end clears. Then the train on the main can go on it’s way.
If only one train is being met, the one in the siding just goes on it’s way too. If it is meeting another train, it has to back the rear end back out on the main. This “sawing motion” is where the term comes from.
The Casey Jones’ wreck involved two trains in the siding “sawing” trains through the station. The rear of a freight train was on the main because they had sawed north to let a previous southbound leave when an air hose burst before they could saw back to the south.
Jeff
As I remember it a saw by is when two trains pass without stopping , one taking the sinding and other keeping the mainline. Both trains MUST be small enought to fit past each other for this to work.
That’s just a rolling meet (see elsewhere on the Forum these days).
Jeff, you could be right, but then just about every meet with a short siding (too short of one of the trains) would be a saw-by, and I didn’t think they were that common.
Two trains, lets say each is 10 cars to long for the siding.
Train A is headed west, B is going east.
A takes the siding, stops 10 cars from the west end.
B holds the main, stops clear of the east end.
A cuts off 10 cars on the main and finishes pulling into the siding, clearing the main…B couples into the 10 excess cars on the main, and shoves ahead enough so that his rear end clears the west end of the siding, and A can now leave the siding at the other end and pull out/ahead on the main, creating enough headroom behind B for train B to back up, cut train A’s cars off on the main between the siding switches, then back up a little more and take the siding Train A was in, running past or around the cars on the main, and going one its way.
Train A now backs up the main to its cars, couples up and goes.
The term saw-by refers to the motions both train A and B have to make, a forward, reverse then forward series of movements, likened to the motion a hand saw makes cutting through wood.
They “saw” past each other.
A double saw by involves both trains having to cut off cars and letting the other train handle part of the movement…double saw- by can waste an entire shift, are avoided by dispatchers at almost any cost, even to the point of holding a train in a terminal if needed.
Draw it out on a piece of paper, it will make sense.
Saw-bys are not common any more, with the computer network and the AEI system, dispatchers have a much better idea of train length, siding length, and can make plans far enough in advance to prevent it.
In the “bad old days” when not telling the dispatcher you were tacking 20 extra cars on a train to clean up the yard till after the train departed, it was a little more common.
It would seem that these days a dispatcher scheduling a meet at a siding too short for both trains could probably spend the rest of his shift contemplating his new career at Wal-Mart.
For what it’s worth, and because I just remembered I had the book. I went and found my copy of John Armstrong’s Track Planning for Realistic Operation. I remembered seeing something in there about the subject.
According to it, and as I said before, depends on what you are used to, the plain saw-by is like I described. The double saw-by is what Ed described.
In any case, I remember years ago listening on the dispatcher’s phone at the local Rock Island depot. They would issue a message to trains that would encounter 57’s train on the single track in time table and train order territory. The Big Train in a Train’s article a few years back. This was after the schedule was abolished and everything ran as extras. The message would be “Do not Saw or Delay.”
Jeff
It’s only a saw-by if the longer train gets to the siding first. If the shorter train can pull all the way into the clear, the longer train just runs on through - no harm, no foul(ing of the main line.)
With modern CTC and computer generated switch lists the probability of two trains making a meet at a siding shorter than either of them is very much reduced. One of them would probably be held at a place where making a meet would not require breaking up and rebuilding a couple of trains.
Chuck
Thanks for the replies, I heard about one being done on the W&A near Nashville.
The October, 2007, issue of TRAINS magazine has a thorough description
of a double saw-by meet on page 78, replete with diagrams.
Joe Mc
Thank you, I have to catch up on my reading! [:)]