This is the first of a series of articles describing the progress of the project.
The use of "now" and "the present" refer to 2006.
The life-expired junction signal on the approach to the ground
level station has been replaced by a new one. Rather than
perpetuate the bracketed twin signals, we have decided to keep up
with modern full size practice and fit a single signal with a "feather"
(five lights in a row) to act as a route indicator. When the point is
set for the platform, a green light is displayed; when set for the
loop the green light remains on but the feather is also illuminated.
The sharp-eyed will notice that the signal goes briefly to red whilst
the point is changing, and returns to green once the blades are
fully over. In the event of the blades being jammed, perhaps by a
stone or a twig, the signal will remain at danger.
Why are feathers used? In the days of semaphore signalling, each
possible diverging route had its own signal arm, often on an
overhead gantry spanning the tracks. Drivers had to know which
arm applied to the route they were about to take, and of course
accidents sometimes happened due to mis-reading the signals.
Modern practice is to fit only one signal at a junction - there is then
no possibility of a driver ignoring a red light because he thought it
applied to another line. Look around the network and you will see
some magnificent junction indicators, sometimes with four or five
feathers pointing in different directions.
There was some debate as to which is the "normal" route and
which is the "diverging" route. Eventually we decided that the
platform road is the "normal" route, because when we are
operating only one train, the loop is not used. This saves the
feather from using power, and shortening its bulb life, for no good
reason.
The signalling gang (Tony Vereker and myself) have further plans
afoot for the ground level system. Next in line will be a system that
allows the driver to select his own route, doing away with the need
for a pointsman. We would also like to bring the Castell lock
nearer to the station, to save the Track Steward the chore of going
to the carriage shed each time a shunting move takes place. A
longer term objective is the track circuiting of the station area, and
three-aspect operation of all the signals. Hopefully the winter
months will see some progress towards these goals.
