Boltar wrote:
The driver who passed A489 knew there was probably a train ahead of
him (it could have moved off). Nevertheless he failed to control his
speed and killed 12 people as a result.

If there was a train in the section ahead of him then why was he given
permission to move past the signal into that section in the first
place as
it seems to me the signal would have been red at that point even if
not broken. AFAICS all that was required was for control to tell the
driver to remain at said signal until the block ahead was clear, this
isn't rocket science.


Because it's an automatic signal, (that means it works autimatically). It
normally shows green, proceed. Causes of it remaining at red, danger include
reasons additional to a train being on that particular section of track.
Such reasons include, a defective signalling circuit, a broken rail
(although that's not guaranteed to keep the signal at danger) or perhaps
flooding of the track. Being in an automatic area no signalbox or control
centre has control over it and so the signaller or controller cannot tell
the driver what the problem is. Therefore the driver cannot be "given
permission". S/He waits one minute and if the signal fails to clear there is
a standing instruction to proceed. This is the "stop and proceed" rule.

This rule relied on the driver travelling at such a speed that he can stop
before reaching an obstruction. Failure of a number of drivers to comply
with this simple rule resulted in a speed limiting device being fitted so
that after the tripcock is activated a maximum speed of 10mph is all that's
available for (IIRC) 5 minutes. Hence delays build up. Even if the whole
railway were controlled by signallers there would still be delay.