In the years I spent with the Mother Road the signals were quite similar across
the territory. All CTC "home" signals were Search Light type(one bulb and the
mechanism "searches" for the correct color filter [lens] to display the aspect)
while the intermediates were three color light signals. Interlocking signals
were also searchlight type.
In multiple main track territory the bridges had single searchlight signals for
intermediates and "stacked" searchlights for "route boards" or "home signals"
such as at crossovers. The top indication governed movements on the main track,
the middle signal, if there were more than two, governed movements through the
turnout and the bottom signal, if present, prescribed restricted speed,
regardless of the route.
Searchlight signals give maintainers the "chills" since there are so many
moving parts and, therefore, so many more chances for things to go wrong. They
are only surpassed by the semaphore as the most hated signal device still in
use.
CTC intermediate signals and ABS signals usually look alike because they are.
Wayside signals are known as "fixed signals" since they are at fixed locations
(not repaired signals).
The Q used Green, Yellow and Red to signal trains. In later years these signals
were displayed in different manners to increase the safe distance between
trains by adding a FLASHING aspect to the yellows and reds. Each aspect
prescribed a specific operating method to trains passing them. Still later the
LUNAR, (bluish-white) RESTRICTING aspect was added as a means of further
keeping trains separated when following each other. Lunar prescribes operating
in a manner that allows stopping in ONE HALF the range of vision but NEVER
exceeding 20MPH. These aspects replaced the "BOTTOM YELLOW" at the entrance to
NON-BONDED sidings. This means that regardless of the frog angle you can NOT go
over 20 when "heading in". Leaving a siding, however, you can go as fast as you
think the cars will stay on the track.
Does this help?
Karl
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