Prototype railroaders tend to avoid the situation where two trains meet at a passing siding only to find that neither is short enough to allow the other train to pass unhindered. It is usually long miles back downtrack to another siding where excess cars may be temporarily dumped to make room on the mainline. Model railroaders carry this avoidance to extremes!
The operation known as a double saw bye allows two overlength trains to successfully pass at a short siding. Model railroaders, through proper planning, may seldom have such a meet at a siding in the middle of nowhere because it isn�t very many feet to the next yard or passing siding. Obviously, with double track mainline, the situation would be extremely rare. Model railroaders have another unique solution . . . just remove a few cars from the layout on one of the offending trains, and presto, it fits.
Model railroaders should learn to operate the railroad, and the double saw bye (or even the common single saw bye) should be used as required. Perhaps these operations are shunned because of lack of understanding of the exact movements required to perform them or because it is “just too much trouble”.
STEP 1 : Both the Eastbound (black) and Westbound (white) trains exceed the siding length. We will assume it is at least 20 miles in either direction to another siding, and the double saw bye is the most efficient operation available. We see from inspection that the Westbound train can be broken between cars 10 and 11, and the Eastbound train can be broken between cars 9 and 10 so that the head ends fit the siding.
STEP 2 : The Westbound train has been broken (in actuality the last five cars would have been dropped as the train pulls into the siding) and the East turnout thrown to the siding.
STEP 3 : The Eastbound train then pulls forward until the West turnout is clear. The 5 Westbound cars are pushed ahead of the engine as required. The West turnout is thrown to the main.
STEP 4 : Just the engine of the Westbound train is moved out onto the mainline, and the West turnout is thrown again to the siding.
STEP 5 : The Westbound engine backs into the siding, and the Eastbound train is broken at the selected point. The extra 6 cars are pulled out onto the mainline, and the West turnout is normalled to the main.
STEP 6 : The remainder of the Eastbound train is backed into the siding (it now fits), leaving the 5 extra Westbound cars sitting on the mainline. The East turnout is normalled to the main.
STEP 7 : The Westbound engine backs to reassemble the entire Westbound train, keeping the 6 extra Eastbound cars behind the engine. This train is then pulled forward until the last car clears the siding.
STEP 8 : The East turnout is thrown to the siding and the Eastbound train runs East on the mainline, leaving enough room behind it for an extra 4-5 cars. The East turnout is normalled to the main.
STEP 9 : The Westbound train backs until car 1 clears the fouling point of the siding. The 6 cars of the Eastbound train are cut here and pulled forward again.
STEP 10 : The West turnout is thrown to the siding, and Eastbound cars 10 through 15 are deposited in the siding.
STEP 11 : The engine is cut off, run back on the mainline, and the West turnout normalled to the main. At this point, the Westbound train can be picked up and proceeds West to its destination.
STEP 12 : The East turnout is again thrown to the siding and the Eastbound train backs into the siding to retrieve the last 6 cars. It then proceeds East to its destination and the operation is complete.
While this may seem like a great deal of trouble, especially since it requires switchmen to break the trains at strategic points and it is imperative that the trains in the operation can perform backing operations without derailing, there is a sense of satisfaction when both trains finally go on their respective way.
Next time a meet occurs as detailed above, don�t say “Oh no, now what?” You can hone your skills as a model railroad operator and work your way through the operation and at the same time perhaps treat the paying public to that most mystifying operation of all, the double saw bye.