On 31 Mar, 16:46, "Peter Masson" wrote:
wrote in message

oups.com... Was at London Bridge the other day platform 6 waiting for a Bedford
train watching trains pass through the platform and noticed that
signal L100 which appears as a 2 aspect but actually capable of
showing double yellow had a indicator box at side which was showing CD
this then changed to RA the signal was showing the same aspects during
the time the sign changed. anyone explain what this was etc.

Most of ther trains which use this platform are Driver Only Operated, so
platform staff have to assist in dispatching trains (see other thread). When
station work is complete, the dispatcher turns a switch which turns the 'CD'
display on, telling the driver to 'Close Doors'. When the doors are closed
and the orange indicator lights on the train have akll gone out, the
dispatcher will turn the switch, to extinguish the 'CD' display and
illuminate the 'RA', telling the driver 'Right Away'.

Is the 'RA' indicator interlocked with the signal, so that it cannot be
displayed if the signal is at red?

Presumably the signal itself uses an LED display, so that the upper head can
display green or yellow, and the lower head yellow or red, and the signal as
a whole can display all four aspects R, Y, YY, and G.

Peter

Thanks must go to the back of the class should have worked it out.