Photo source and question

[DF Cramer]

    Nachod signals are normally dark upon approach if the track is clear.
Upon reaching the contactor, the signal system on your end of the block will
turn amber and on the other end turn red.  When you leave the other end of
the block the system will go dark when you go through the contactor.  The
contactors are set to react in two directions.
    If a car has entered the block from another direction, the signal will
be red on your end and you must wait until they clear the contactor on your
end.
    Upon reaching a signal and it is amber, you may proceed knowing there is
a car in front of you traveling in the same direction.
    The system counts every car entering the block and keeps track of the
same number exiting the block.
    Yes they do malfunction.  They can be reset from inside the signal box
on a line pole.
    We use them at the Pennsylvania Trolley Museum.  Come out some day and
watch them in action.

DFCramer--Teacher-Trombonist-Historian-Conductor

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