On Jan 11, 6:28*pm, (Neil Williams)
wrote:
Does anyone know the purpose of the apparently approach-controlled
signal in the middle of the platform on the westbound Moorgate
Met/Circle/H&C platform?

Neil

--
Neil Williams
Put my first name before the at to reply.

It's a Draw Up Signal. They are basically speed controlled stop
signals to protect a set of points in advance of the next, in this
case, station starting signalm if the starter's overlap is not
sufficient to protect a collision at the fouling point. If the signal
in advance was at danger then the Draw Up signal (identified by adding
a 0 or 00 to the number on the starter) whould show a red aspect,
until the timing section knew that the train was slow enough. It would
then show a yellow (or in some cases a green aspect).

On Sun, 11 Jan 2009 13:29:14 -0800 (PST),
wrote:

It's a Draw Up Signal. They are basically speed controlled stop
signals to protect a set of points in advance of the next, in this
case, station starting signalm if the starter's overlap is not
sufficient to protect a collision at the fouling point. If the signal
in advance was at danger then the Draw Up signal (identified by adding
a 0 or 00 to the number on the starter) whould show a red aspect,
until the timing section knew that the train was slow enough. It would
then show a yellow (or in some cases a green aspect).

Thanks. Is the main (starter) signal also approach-controlled, then,
as I don't recall ever *not* having been slowed half way up the
platform.

Neil

--
Neil Williams
Put my first name before the at to reply.

On Jan 11, 11:25*pm, (Neil Williams)
wrote:
On Sun, 11 Jan 2009 13:29:14 -0800 (PST),

wrote:
It's a Draw Up Signal. They are basically speed controlled stop
signals to protect a set of points in advance of the next, in this
case, station starting signalm if the starter's overlap is not
sufficient to protect a collision at the fouling point. If the signal
in advance was at danger then the Draw Up signal (identified by adding
a 0 or 00 to the number on the starter) whould show a red aspect,
until the timing section knew that the train was slow enough. It would
then show a yellow (or in some cases a green aspect).

Thanks. *Is the main (starter) signal also approach-controlled, then,
as I don't recall ever *not* having been slowed half way up the
platform.

Neil

--
Neil Williams
Put my first name before the at to reply.

As far as I know it is not speed controlled.
However, in areas where signalling is operated by computer or
programme machine, many signals only clear (or call the route) on the
approach of a train. \Though it may clear straight away if it is
selected manually.