Every once in awhile I run across a reference to a foreign country's signaling system that used token, or other objects, to permit trains to operate sections of track. It is a simple system which only allows one train (the one with the token) to operate in a block. It sort of reminds me of bathroom passes in grade school.
I have always wondered something though. How do multiple trains heading the same direction receive tokens? If there are three northbound trains, the first would bet the token to operate in a section and it would end up at the northern end of the section after the first train is done with it. How does the token get to the southern end of the block to be handed to the next train? I would assume that having multiple tokens per block would negate the benefit of the system entirely.
I haven't read much about usage of this system in the USA, which is probably why I haven't come across the answer already.
Modeling the D&H in 1984: http://dandhcoloniemain.blogspot.com/
I have now been told that this "holding" process was somewhat mechanized with machines at the sidings, elctrically connected, counting ins and outs on some railroads, possibly in the UK? The article in the posting preceding mine should have the answer, and i can read it when I am at HU and have wideband.
In the early days of Israel Railways, it was in use, and in 1960 I saw it in operation on the then Jerusalem - Tel Aviv line. It makes the assumption that traffic alternates on each single track section. If a "second section" or more of a particular movement is required, the last, rather than the first, of the multiple movements handles the token. The opposing train waiting at the siding sees the first train without receiving a token and waits until the last which brings the token. This of course requires the sidings to be manned, which they were, with the operator responsible for switches and signals also holding the token between receiving it and giving it to the last of a serieis of eections,
I tried to sell my two cents worth, but no one would give me a plug nickel for it.
I don't have a leg to stand on.