Signals are crucial to the running of a safe and efficient railway.
The first signals were operated by hand by a signal 'policeman'.
The
introduction of signal boxes gave central control using rods nad wires,
and later on, point and signal interlocking. When combined with the
telegraph bell code system and single-line block tokens, signal boxes
finally were able to work together to operate trains more safely.
Today, semaphore signals and signal boxes have all but disappeared, but
are still used in Cornwall, a few other lines like the Settle to
Carlisle and, of course, preserved railways.
Apart from the way they look, semaphore
signals differ from modern signals in two ways. The distant signal is
usually separate from any stop signal, being placed about a quarter
mile ahead of the home signal. This warns trains in time to stop
without the need to run miles of wire to the previous signal. The
second difference is that they are normally at 'danger' except from
when a train is cleared, whilst modern signals are green unless the
line ahead is occupied.
Ratio 'Quick Assembly' signals reflect
those used by railway companies from the 1930s onwards. The quick
assembly kits allow you to easily make home, distant, junction and
bracket signals. They include signal operating wire and lever.