There is no underground version of token block signal. Also the on-staff box is available only overground. Is that intentional?
Also, was there a color light (and undergoud) version of combined absolute block signal - the one with red and yellow arm?
I have modified the one train staff cabinet to be able to be built underground.
As to token block signalling, I am not aware of any real life example of electric token block signalling being used underground - I cannot imagine how the tablet exchange system would actually work in a tunnel. Are you aware of any examples of this?
As to colour light combined signals - I am not sure whether there were any significant examples of this, as I suspect that proper multiple aspect signalling was introduced whenever this would have been relevant. Are you aware of any significant historical examples of a signal of this type? Presumably, it would not be the same as a multiple aspect signal, but would show two simultaneous aspects?
I do not know any examples of either. It was just the demo game that made me think of them. In practice I see no problem with having a token machine placed in underground station (though not in plain tunnel). But I expect that most of the underground lines were double tracked anyway, so tokens were probably not necessary.
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